ARTICLE OPEN ACCESS

Clinical spectrum of POLR3-relatedleukodystrophy caused by biallelic POLR1Cpathogenic variantsLaurence Gauquelin MD FRCPC Ferdy K Cayami MD Laszlo Sztriha MD PhD Grace Yoon MD FRCPC

Luan T Tran MSc Kether Guerrero MSc Franccedilois Hocke MD Rosalina ML van Spaendonk PhD

Eva L Fung MB ChB Stefano DrsquoArrigo MD Gessica Vasco MD PhD Isabelle Thiffault PhD FACMG

Dmitriy M Niyazov MD Richard Person PhD FACMG Kara Stuart Lewis MD Evangeline Wassmer MD MSc

Trine Prescott MD Penny Fallon MBBS MRCPCH Meriel McEntagart MD Julia Rankin MD PhD

Richard Webster MBBS MSc FRACP Heike Philippi MD Bart van de Warrenburg MD PhD

Dagmar Timmann MD Abhijit Dixit MD and Claire Searle MB ChB MRCP DDD Study Nivedita Thakur MD

Michael C Kruer MD Suvasini Sharma MD DM Adeline Vanderver MD Davide Tonduti MD PhD

Marjo S van der Knaap MD PhD Enrico Bertini MD Cyril Goizet MD PhD Sebastien Fribourg PhD

Nicole I Wolf MD PhDDagger and Genevieve Bernard MD MSc FRCPCDagger

Neurol Genet 20195e369 doi101212NXG0000000000000369

Correspondence

Dr Bernard

genevievebernardmcgillca

AbstractObjectiveTo determine the clinical radiologic and molecular characteristics of RNA polymeraseIII-related leukodystrophy (POLR3-HLD) caused by biallelic POLR1C pathogenic variants

MethodsA cross-sectional observational study involving 25 centers worldwide was conducted Clinicaland molecular information was collected on 23 unreported and previously reported patientswith POLR3-HLD and biallelic pathogenic variants in POLR1C Brain MRI studies werereviewed

These authors contributed equally to the manuscript

DaggerDual senior authors

From the Department of Neurology and Neurosurgery (LG LTT KG GB) McGill University Montreal Canada Department of Pediatrics (LG LTT KG GB) McGillUniversity Montreal Canada Division of Clinical and Metabolic Genetics and Division of Neurology (LG GY) The Hospital for Sick Children University of Toronto TorontoCanada Department of Child Neurology (FKC MSVDK NIW) Emma Childrenrsquos Hospital AmsterdamUniversity Medical Centers Vrije Universiteit Amsterdam and AmsterdamNeuroscience Amsterdam The Netherlands Department of Clinical Genetics (FKC RMVS) VU University Medical Center Amsterdam The Netherlands Department of HumanGenetics (FKC) Center for Biomedical Research Diponegoro University Semarang Indonesia Department of Pediatrics (LS) Faculty of Medicine University of Szeged SzegedHungary Child Health and Human Development Program (LTT KG GB) Research Institute of the McGill University Health Center Montreal Canada Division of Medical GeneticsDepartment of SpecializedMedicine (LTT KG GB) McGill University Health Center Montreal Canada Centre de Reference Neurogenetique (FH CG) Service de Genetique CHUBordeaux Bordeaux France Department of Pediatrics (ELF) Faculty of Medicine The Chinese University of Hong Kong Hong Kong China Developmental Neurology Department(SDA) Fondazione IRCCS Istituto Neurologico C Besta Milan Italy Neuroscience and Neurorehabilitation Department (GV) Bambino Gesu Childrenrsquos Hospital Rome Italy Centerfor Pediatric GenomicMedicine (IT) ChildrenrsquosMercy Hospitals and Clinics Kansas City MO University ofMissourindashKansas City School ofMedicine (IT) Kansas City MO Departmentof Pathology and Laboratory Medicine (IT) Childrenrsquos Mercy Hospitals Kansas City MO Department of Pediatrics (DMN) Section of Medical Genetics Ochsner for Children NewOrleans LA GeneDx (RP) Gaithersburg MD Division of Neurology (KSL) Barrow Neurological Institute Phoenix Childrenrsquos Hospital Phoenix AZ Department of PediatricNeurology (EW) Birmingham Childrenrsquos Hospital Birmingham United Kingdom Department of Medical Genetics (TP) Telemark Hospital Skien Norway Department of PaediatricNeurology (PF) St Georges University Hospital NHS Foundation Trust London United Kingdom Clinical Genetics Service (MM) St Georgersquos University Hospitals NHS FoundationTrust London United Kingdom Clinical Genetics Department (JR) Royal Devon and Exeter Hospital NHS Trust Exeter United Kingdom Department of Neurology and Neurosurgery(RW) The Childrenrsquos Hospital at Westmead Westmead New South Wales Australia Center of Developmental Neurology (HP) Frankfurt Germany Department of Neurology(BVDW) Donders Institute for Brain Cognition and Behaviour Radboud University Medical Center Nijmegen The Netherlands Department of Neurology (DT) Essen UniversityHospital University of Duisburg-Essen Essen Germany Department of Clinical Genetics (AD CS) Nottingham University Hospitals NHS Trust Nottingham United KingdomWellcome Sanger Institute (DDD Study) Wellcome Genome Campus Cambridge United Kingdom Department of Pediatrics (NT) Division of Child Neurology University of TexasHealth Science Center Houston TX United States of America Movement Disorders Center and Neurogenetics Research Program (MCK) Barrow Neurological Institute PhoenixChildrenrsquos Hospital Phoenix AZ Program in Neuroscience (MCK) Arizona State University Tempe AZ United States of America Division of Neurology (SS) Department ofPediatrics Lady Hardinge Medical College and Associated Kalawati Saran Childrenrsquos Hospital New Delhi India Division of Neurology (AV) Childrenrsquos Hospital of PhiladelphiaPhiladelphia PA Department of Neurology (AV) Perelman School ofMedicine University of Pennsylvania Philadelphia PA United States of America Department of Child Neurology(DT) Neurological Institute C Besta Foundation IRCCS Milan Italy Department of Functional Genomics (MSVDK) VU University Amsterdam The Netherlands Unit of Neuro-muscular and Neurodegenerative Disorders (EB) Laboratory of Molecular Medicine Bambino Gesu Childrenrsquos Hospital Rome Italy Laboratoire MRGM INSERM U1211 UniversityBordeaux Bordeaux France Universite de Bordeaux (SF) INSERM U1212 CNRS 5320 Bordeaux France and Department of Human Genetics (GB) McGill University MontrealCanada

Go to NeurologyorgNG for full disclosures Funding information is provided at the end of the article

The Article Processing Charge was funded by the Canadian Institutes of Health Research

This work was presented as a poster at the 46th Annual Child Neurology Society Meeting Kansas City MO (2017) An abstract was published in Annals of Neurology

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 40 (CC BY-NC-ND) which permits downloadingand sharing the work provided it is properly cited The work cannot be changed in any way or used commercially without permission from the journal

Copyright copy 2019 The Author(s) Published by Wolters Kluwer Health Inc on behalf of the American Academy of Neurology 1

ResultsFourteen female and 9 male patients aged 7 days to 23 years were included in the study Most participants presented early in life(birth to 6 years) and motor deterioration was seen during childhood A notable proportion of patients required a wheelchairbefore adolescence suggesting a more severe phenotype than previously described in POLR3-HLD Dental ocular andendocrine features were not invariably present (70 50 and 50 respectively) Five patients (22) had a combination ofhypomyelinating leukodystrophy and abnormal craniofacial development including 1 individual with clear Treacher Collinssyndrome (TCS) features Brain MRI revealed hypomyelination in all cases often with areas of pronounced T2 hyperintensitycorresponding to T1 hypointensity of the white matter Twenty-nine different pathogenic variants (including 12 new disease-causing variants) in POLR1C were identified

ConclusionsThis study provides a comprehensive description of POLR3-HLD caused by biallelic POLR1C pathogenic variants based on thelargest cohort of patients to date These results suggest distinct characteristics of POLR1C-related disorder with a spectrum ofclinical involvement characterized by hypomyelinating leukodystrophy with or without abnormal craniofacial developmentreminiscent of TCS

Leukodystrophies are a heterogeneous group of geneticallydetermined disorders affecting the cerebral white matter withor without involvement of the peripheral nervous system12

Hypomyelinating leukodystrophies characterized by a severeand permanent myelin deficit form a large subgroup withinthe leukodystrophies3ndash5

RNA polymerase IIIndashrelated leukodystrophy (POLR3-HLD)is typically characterized by a combination of neurologic andnon-neurologic manifestations67 Cerebellar features areusually prominent with pyramidal signs involving the lowermore than the upper extremities The non-neurologic mani-festations include dental abnormalities endocrine featuresand myopia6 Brain MRI generally shows diffuse hypomyeli-nation (mild T2 hyperintensity and variable T1 signal in-tensity of the white matter) with relative myelin preservation(T2 hypointensity) of specific structures4ndash68 Cerebellar at-rophy and thinning of the corpus callosum are common as-sociated findings68

POLR3-HLD is an autosomal recessive disorder It was firstassociated with pathogenic variants in POLR3A or POLR3Bencoding the largest subunits of RNA polymerase III69ndash13 Itwas also recently associated with a homozygous pathogenicvariant in POLR3K14 In 2015 variants in POLR1C encodinga common POLR1 and POLR3 subunit were identified in 8patients with POLR3-HLD15 Pathogenic variants inPOLR1C were previously associated with autosomal recessiveTreacher Collins syndrome (TCS) a congenital disorder ofcraniofacial development in 3 unrelated patients16

To date the clinical spectrum of POLR3-HLD caused bybiallelic POLR1C pathogenic variants has not been described

in detail We present a thorough phenotypic description ofthis condition by reporting the clinical imaging and molec-ular features of 23 genetically proven cases

MethodsTwenty-three individuals were included in this multicentercross-sectional study The participants were recruited be-tween 2016 and 2018 based on their clinical and radiologicfeatures consistent with POLR3-HLD combined withproven pathogenic variants in POLR1C They wererecruited from 25 different centers worldwide Eight of the23 patients have previously been published in the originalarticle identifying POLR1C as a causative gene for POLR3-HLD in 201515

A retrospective chart review was conducted for each partici-pant Participants of all ages were included in the studyClinical and demographic information was collected througha questionnaire distributed to the referring physicians Sex wasdocumented as observed by the physicians Consanguinity aswell as ethnicity andor country of origin were also assessedas reported by the participants and their families

Brain MRI studies of 22 participants were reviewed by GBand LG (11) NIW (10) or DT (1) MRI was not avail-able for 1 individual who died in the neonatal period Theavailable studies were analyzed based on established criteriafor hypomyelination and previously published imaging char-acteristics of POLR3-HLD4ndash68 Biallelic pathogenic variantsin POLR1C were identified or confirmed in clinically certifiedlaboratories The human genome version used for annotationwas GRCh37hg19

GlossaryPOLR3-HLD = RNA polymerase III-related leukodystrophy TCS = Treacher Collins syndrome

2 Neurology Genetics | Volume 5 Number 6 | December 2019 NeurologyorgNG

Figure 3B was generated using the Lollipops software17 Togenerate figure 3C the sequences of human POLR1C andyeast RPAC40 were aligned using Seaview18 The yeastequivalent residues found mutated in patients were identifiedusing the sequence alignment and were positioned on theyeast RPAC40 taken from the POLR1 structure (PDB5M5W)19 Figure 3C was created using Pymol20

Standard protocol approvals registrationsand patient consentsWritten informed consent was obtained from all participants ortheir legal representatives Consent was obtained from 1 par-ticipant (patient 19) for disclosure of a photograph The studywas approved by the ethics committees of theMcGill UniversityHealth Center (11-105-PED) and VU University MedicalCenter (2018300) The patients and their families did not re-ceive financial compensation for their participation in the study

Data availabilityThe data sets were deposited in a publicly available database(ClinVar number SUB5043960) Anonymized data will beshared by request from any qualified investigator

ResultsDemographic dataTwenty-three individuals (14 female and 9 male patients)from 21 families were included in the study There were 2consanguineous families (patients 1 and 13) The patientsrsquoage at their last clinical assessment ranged from 7 days to 23years (median 10 years) The demographic characteristics ofthe 23 participants are reported in table 1

Neurologic manifestationsThe clinical characteristics of the participants are summarizedin table 1 The onset of symptoms was in infancy or child-hood ranging from birth to 6 years Most patients (172374) presented in the first 2 years of life including 4 in theneonatal period For the majority of participants the initialsymptoms consisted of motor difficulties (delayed motordevelopment tremor or gait impairment) Limited in-formation was available on patient 202 who died early in theneonatal period (at age 7 days) Of the other 22 individuals 9(41) did not achieve independent walking and ambulationwas delayed in most of the remaining patients Nine of 22participants (41) had dysphagia and 5 of them requireda gastrostomy tube (between ages 9 months and 10 years)

On examination all 22 participants who were evaluated be-yond the neonatal period had cerebellar signs (ataxia dysar-thria dysmetria intention tremor and nystagmus) and manyhad prominent tremor Pyramidal signs were often morepronounced in the lower extremities (1422 participants64) Dystonia was noted in 722 patients (32) Cognitiveimpairment (intellectual disability andor cognitive regression)was variable seen in 1521 individuals (71) who were old

enough to be evaluated Global deterioration with infectionswas noted in almost half (1022 45) In addition seizureswere reported in 522 patients (23) 1 of whom had eventsduring febrile episodes only and was not treated with anti-epileptic medication

Motor regression occurred in most of the patients (162273) and was seen during childhood between ages 2 and 8years except for 2 individuals who experienced regressionlater (at 12 and 16 years) The use of a wheelchair was oftenrequired before adolescence (1322 59) Two of 23patients died One of them died in the neonatal period(patient 202) and the other at age 10 years (patient 19)both from cardiorespiratory failure Both had presented inthe neonatal period and exhibited abnormal craniofacialdevelopment Patient 202 also had cardiac arrhythmiasrespiratory distress syndrome and suspected adrenalinsufficiency

Non-neurologic manifestationsPatient 19 was the only one described by the referring clini-cian as having facial features compatible with TCS includingdownslanted palpebral fissures strabismus bitemporal nar-rowing external ear abnormalities cleft palate and prominentmicrognathia (figure 1) Four other individuals (patients 2 317 and 202) showed subtle evidence of abnormal craniofacialdevelopment with mild mandibular hypoplasia Of note pa-tient 9 did not exhibit craniofacial abnormalities but hadlaryngomalacia

The entire dental ocular and endocrine features often seen inPOLR3-HLD were not always present but all patients werefound to have at least 1 non-neurologic manifestation Dentalabnormalities were seen in 1623 individuals (70) delayederuption oligodontia or hypodontia abnormal tooth shapemalocclusion neonatal teeth or frequent cavities Half of thepatients who were evaluated beyond the neonatal period hadmyopia (1122 50) Short stature was present in 1122 (50)

Radiologic characteristicsRadiologic characteristics are presented in table 2 and figure 2Brain MRI studies were available for 2223 participants(96) All showed diffuse hypomyelination with relativepreservation (T2 hypointensity) of specific structures Pre-served myelination of the anterolateral thalamus was seen in2122 individuals (95) and optic radiation in 1822 (82)However several patients did not exhibit all the radiologiccharacteristics previously described in POLR3-HLD Relativemyelin preservation was less consistently seen in the posteriorlimb of the internal capsule (1222 55) dentate nucleus(1222 55) and pallidum (1122 50) In addition 1222cases (55) showed hypointense medial lemniscus Thepresence of myelin islets (better myelinated areas within thewhite matter T1 hyperintense and T2 hypointense21) wasalso noted in a few patients (322 14)

NeurologyorgNG Neurology Genetics | Volume 5 Number 6 | December 2019 3

Table 1 Demographic clinical and molecular characteristics of 23 patients with POLR3-HLD caused by biallelic POLR1C pathogenic variants

Patient cDNA Protein DNA Protein

Sexethnicityandor countryof origin

Age atonset(y)

Use of awheelchair(y)

DysphagiaG-tube (y) Microcephaly

Cerebellarsigns

Pyramidalsigns Dystonia

TCSphenotype

AbNcraniofacialdevelopment Myopia

DentalAbN

Shortstature

Hypogonadotropichypogonadism

Death(age)

1a c95AgtT pAsn32Ile c95AgtT pAsn32Ile MLibyan 1 minus minusminus minus + + minus minus minus minus + + minus minus

2 c221AgtG pAsn74Ser c221AgtG pAsn74Ser MHungarian 1 6 +10 minus + + minus minus + minus + minus NA minus

3 c436TgtC pCys146Arg c883_885delAAG

pLys295del MAsian(Chinese)

1 minus +minus + + + + minus + minus + + pP minus

4 c77CgtT pThr26Ile c326GgtA pArg109His FCaucasian(Armenian)

2 minus minusminus minus + + minus minus minus minus + minus pP minus

5 c193AgtG pMet65Val c572GgtA pArg191Gln FCaucasian(Australian)

15 8 +minus minus + + minus minus minus minus minus + minus minus

6 c326GgtA pArg109His c970GgtA pGlu324Lys FCaucasian(Turkish)

4 11 +minus minus + + + minus minus + minus + minus minus

7 c395GgtA pGly132Asp c461_462delAA

pLys154fs4 FCaucasian(German)

12 0 minusminus minus + minus minus minus minus + + + pP minus

8 c281TgtC pVal94Ala c785TgtC pIle262Thr MCaucasian(Dutch)

12 0 NA minus + minus minusM minus minus + minus minus minus minus

9b

(303565)c69+1GgtA pAsn24Asnfs55

(prediction)c836GgtA pArg279Gln MCaucasian

(British)0 NA +075 + + + minus minus minusL minus + minus pP minus

101 c916_920delTATAT

pTyr306Leufs4 c938CgtT pThr313Met MCaucasian 4 minus minusminus minus + minus minus minus minus minus + minus minus minus

102 c916_920delTATAT

pTyr306Leufs4 c938CgtT pThr313Met MCaucasian 4 minus minusminus minus + minus minus minus minus + + minus minus minus

11 c193AgtG pMet65Val c733GgtA pVal245Met MCaucasian(Dutch)

2 minus minusminus minus + minus minus minus minus + minus minus minus minus

12 c313AgtT pIle105Phe c916_920delTATAT

pTyr306Leufs4 FCaucasian(English)

3 12 minusminus + + minus minus minus minus + + minus pP minus

Continued

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Table 1 Demographic clinical and molecular characteristics of 23 patients with POLR3-HLD caused by biallelic POLR1C pathogenic variants (continued)

Patient cDNA Protein DNA Protein

Sexethnicityandor countryof origin

Age atonset(y)

Use of awheelchair(y)

DysphagiaG-tube (y) Microcephaly

Cerebellarsigns

Pyramidalsigns Dystonia

TCSphenotype

AbNcraniofacialdevelopment Myopia

DentalAbN

Shortstature

Hypogonadotropichypogonadism

Death(age)

13ab

(279603)c836GgtA pArg279Gln c836GgtA pArg279Gln FCaucasian

(English)2 7 minusminus + + + + minus minus minus minus + pP minus

14 c88CgtT pPro30Ser c916_920delTATAT

pTyr306Leufs4 FNorwegian 03 0 minusminus minus + minus + minus minus + + minus pP minus

15 c221AgtG pAsn74Ser c502GgtA pVal168Met +splicing error

FCaucasian(English)

0 0 +1 + + + + minus minus + + + pP minus

16 c79AgtG pThr27Ala c349GgtC pAla117Pro FCaucasian 6 minus minusminus minus + + minus minus minus minus + minus minus minus

17 c322CgtT pHis108Tyr c325CgtT pArg109Cys FCaucasian 04 0 +minus + + + minus minus + minus + minus minus minus

18 c70-1GgtA pAsn24Profs27(prediction)

c835CgtT pArg279Trp FAfricanAmerican

2 11 minusminus + + + minus minus minus minus minus + pP minus

19 c699CgtG pTyr233 c883_885delAAG

pLys295del FCaucasian 0 3 +2 + + + + + + + + + pP 10 y

201 c88CgtT pPro30Ser c615delC pGln206Lysfs48 MCaucasian 1 4 +7 + + + + minus minus +C + + pP minus

202 c88CgtT pPro30Ser c615delC pGln206Lysfs48 FCaucasian 0 NA NA + NA NA NA minus + NA minus NA pP 7 d

21 c77CgtT pThr26Ile c77CgtT pThr26Ile FAsian 35 minus -- minus + minus minus minus minus + + + pP minus

Abbreviations AbN = abnormal C = cataracts G-tube = gastrostomy tube L = laryngomalacia M = myoclonus NA = not available P = puberty pP = prepubertal POLR3-HLD = RNA polymerase III-related leukodystrophyPatients 1ndash8 have previously been published15 Patients 9 and 13 have been reported in DECIPHER (identifier between brackets) Novel disease-causing variants are in bolda Consanguinityb Contribution of the DDD study

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The vast majority exhibited thinning of the corpus callosum(2122 95) and cerebellar atrophy (1922 86) oftenmild Posterior white matter atrophy was present in 722cases (32) Diffuse supratentorial atrophy was also seen in622 participants (27) without clear correlation with age orclinical severity

In 1622 individuals (73) MRI revealed areas of prominentT1 hypointensity of the white matter which is not typicallyseen in POLR3-HLD One patient (patient 201) exhibitedvery atypical MRI features with pronounced T2 hyper-intensity and corresponding T1 hypointensity of the deepwhite matter and polymicrogyria

Molecular findingsA total of 29 different variants in POLR1C were identifiedincluding missense variants frameshift variants and splice sitevariants (table 1 and figure 3) Twelve novel disease-causingvariants in POLR1C were identified Four participants werehomozygous and 19 were compound heterozygous Themost common variants were c916_920del (pTyr306-Leufs4) identified in 4 individuals from 3 unrelated families(patients 101 102 12 and 14) c88CgtT (pPro30Ser) in 3participants from 2 unrelated families (patients 14 201 and202) and c221AgtG (pAsn74Ser) in 2 patients from 2 un-related families (patients 2 and 15) Segregation was con-firmed in family members for whom DNA was available forsequencing

DiscussionOur findings suggest that POLR3-HLD caused by biallelicPOLR1C variants is characterized by a spectrum of clinicalfeatures with hypomyelinating leukodystrophy at times ac-companied by craniofacial abnormalities reminiscent of TCSwith varying severity In addition to the 5 patients who hada combination of neurologic and craniofacial manifestations 1patient had laryngomalacia without any other signs of ab-normal craniofacial development Narrowing of the airway isanother common manifestation of TCS that is not typicallyseen in POLR3-HLD22

TCS is a ribosomopathy and all 3 genes implicated to date(TCOF1 POLR1D and POLR1C) are involved in pre-rRNAtranscription23 Most cases of TCS are caused by heterozygouspathogenic variants in TCOF1222425 Autosomal recessive TCSattributed to pathogenic variants in POLR1C is rare with only 5affected individuals reported since 20111626 Of these 5 patients4 had normal motor development and there was no informationavailable for the fifth Brain imaging findings were notreported1626 POLR3-HLD is known to be associated withvariable clinical severity with later onset and very mild course insome patients6 There is 1 reported patient in the literature withno neurologic signs at age 21 years6 It is alsowell established thathypomyelination on brainMRI is not obligate in POLR3-relateddisorder27ndash30 Therefore we cannot exclude that the 5 patientswith TCS attributed to variants in POLR1C could have a mildform of POLR3-HLD with only subtle neurologic manifes-tations if any We suspect that there is a spectrum of diseaseseverity for both the hypomyelination and the non-neurologicmanifestations in POLR3-HLD caused by biallelic POLR1Cvariants as it is the case in patients carrying pathogenic variantsin POLR3A or POLR3B6 It is likely that POLR1C-related dis-order is underrecognized

Our patients appeared overall to have a more severe neu-rologic phenotype than the previously reported patientswith POLR3-HLD6 Individuals with biallelic POLR1Cvariants seem to have the most severe neurologic symp-toms followed by patients with biallelic POLR3A variantsAt the other end of the spectrum POLR3B is known to beassociated with milder clinical features6 In our cohortpatients with an earlier onset of symptoms had a moresevere clinical course did not achieve ambulation and weremicrocephalic features that are very rarely associated withTCS222425 There was no clear genotype-phenotype cor-relation Two of the 4 patients with onset of symptoms inthe neonatal period were also part of the group that hadabnormal craniofacial development Otherwise the patternof cerebellar and pyramidal signs seen in most of our 23patients was consistent with the established phenotype ofPOLR3-HLD

Neurologicmanifestations are rarely seen in cases of typical TCScaused by heterozygous pathogenic variants in TCOF1222425

Delayed speech development is thought to be secondary to

Figure 1 Photograph of patient 19 showing facial featurescompatible with Treacher Collins syndrome (TCS)

Photograph of patient 19 at age 10 years She had facial features inkeeping with TCS including downslanted palpebral fissures strabismusbitemporal narrowing external ear abnormalities cleft palate andprominent micrognathia

6 Neurology Genetics | Volume 5 Number 6 | December 2019 NeurologyorgNG

Table 2 Brain MRI characteristics of 22 patients with POLR3-HLD caused by biallelic POLR1C pathogenic variants

Patient Hypomyelination

T2Hypointensedentatus

T2Hypointensepallidum

T2HypointenseCST in PLIC

T2Hypointenselateralthalamus

T2Hypointenseopticradiation

Thincorpuscallosum

Posteriorwhitematteratrophy

Supratentorialatrophy

Cerebellaratrophy

WM areas ofmarked T1hypointensity

T2Hypointensemediallemniscus

Otherfindings

1 + + + minus + + + minus + + + +

2 + minus minus minus + + + minus minus + + +

3 + minus + minus minus + + minus minus + + minus

4 + + + minus + + + minus minus + + +

5 + minus minus + + + + minus minus + + minus

6 + + minus + + + + + minus + + +

7 + minus minus + + + + minus minus + + minus

8 + minus minus + + + + minus + + + +

9 + + minus + + + + minus + minus + +

101 + + + + + + + minus minus + + + MI

102 + + + + + + + minus minus + + + MI

11 + + + + + + + + minus + + minus

12 + + + minus + + + + minus + minus minus

13 + + + + + + + minus minus + + minus

14 + minus minus minus + minus minus minus minus minus minus minus

15 + minus minus minus + minus + minus + + minus minus

16 + + + minus + + + + + + + +

17 + minus minus minus + minus + + minus + minus +

18 + + + + + + + minus minus + + +

19 + minus + minus + minus + + + minus minus +

201 + minus minus + + + + minus minus + + minus PMG

202 NA NA NA NA NA NA NA NA NA NA NA NA

21 + + minus + + + + + minus + minus minus MI

Abbreviations CST = corticospinal tracts MI = myelin islets PLIC = posterior limb of the internal capsule PMG = polymicrogyria POLR3-HLD = RNA polymerase III-related leukodystrophy NA = not available WM = white matterMyelin islets and hypointense medial lemniscus are best assessed on 3T imaging21

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conductive hearing loss and delayed motor development ishypothesized to be associated with atypical and severe TCSpresentation24 Intellectual disability is also very uncommonthere are 2 reported cases of TCS with intellectual disabilitycaused by deletions of TCOF1 with the cognitive impairmentbeing attributed to the deletion of contiguous genes25 In ad-dition there are a few reports of exceptionally severe cases ofTCS with craniosynostosis and CNS anomalies (encephaloceleand holoprosencephaly)31 None of these patients had hypo-myelination Thus the overlap between POLR3-HLD and TCSappears to be unique to POLR1C-related disorder althoughvariants in POLR1A first associated with acrofacial dysostosis(another category of craniofacial malformations) have also re-cently been identified as causing leukoencephalopathy32

A similar clinical overlap with another category of craniofacialdefects was identified in POLR3A-related disorder BiallelicPOLR3A variants were found to cause Wiedemann-

Rautenstrauch syndrome a neonatal form of segmental pro-geria associated with growth retardation and abnormal facialfeatures with some patients also exhibiting progressive neu-rologic symptoms33 It was suggested that the specific com-bination of a variant with a strong functional effect on theprotein with a milder hypomorphic variant leads to theWiedemann-Rautenstrauch syndrome phenotype33

Regarding non-neurologic manifestations our findings re-inforce that it is crucial to screen patients with POLR3-HLDfor dental abnormalities myopia and short stature Thedental abnormalities are varied and can be very subtle Thelower frequency of myopia in our cohort compared withthe previously reported patients with POLR3A or POLR3Bvariants (50 vs 87) may be at least partly due to the factthat our patients were young Myopia is known to progressover time in patients with POLR3-HLD and may not havestarted in the younger patients

Figure 2 Brain MRI characteristics of 4 patients with POLR3-HLD caused by biallelic POLR1C pathogenic variants

Sagittal T1 (A F K and P) axial T2 (BndashD GndashI LndashN and QndashS) and axial T1 (E J O and T) images (AndashE) MRI of patient 18 obtained at age 11 years showing diffusehypomyelination with superimposed areas of pronounced T2 hyperintensity (C and D) and corresponding T1 hypointensity (E) Thinning of the corpuscallosum and mild superior vermis atrophy are also seen (A) as well as preserved myelination of the dentate nucleus (B) globus pallidus anterolateralnucleus of the thalamus and optic radiation (C) (FndashJ) MRI of patient 4 obtained at age 5 years showing diffuse hypomyelination with preservation of thedentate nucleus (G) anterolateral nucleus of the thalamus and optic radiation (H) There is also thinning of the corpus callosum andmild vermis atrophy (F)Areas ofmarked T2 hyperintensity of thewhitematter are seen (H and I) with corresponding pronounced T1 hypointensity (J) (KndashO)MRI of patient 1 obtainedat age 5 years showing a thin corpus callosum (K) relative preservation of myelination of the dentate nucleus (L) and absent T2 hypointensity of thecorticospinal tracts in the posterior limb of the internal capsule (M) (PndashT) MRI of patient 201 obtained at age 3 years showing areas of prominent T2hyperintensity of the white matter (R and S) with corresponding T1 hypointensity (T) especially in the deep white matter There is also bilateral frontalpolymicrogyria (R S and T) POLR3-HLD = RNA polymerase III-related leukodystrophy

8 Neurology Genetics | Volume 5 Number 6 | December 2019 NeurologyorgNG

In POLR3-HLD caused by POLR3A or POLR3B variantsbrain MRI generally shows diffuse hypomyelination withrelative myelin preservation of the anterolateral thalamusoptic radiation globus pallidus dentate nucleus and pyra-midal tracts in the posterior limb of the internal capsule4ndash68

In patients carrying POLR1C variants the dentate nucleusappeared to be less commonly spared (55 compared with93 in the literature)6 Myelin islets and hypointensemedial lemniscus were seen in only 14 and 55 of ourpatients respectively however it is important to mentionthat these signs are best assessed on 3T imaging21 Almostall of our patients exhibited thinning of the corpus cal-losum regardless of their age or of the severity of supra-tentorial atrophy It is therefore unlikely to represent onlythe result of diffuse atrophy Alternatively it could reflecta more severe underlying white matter involvement Thishypothesis is supported by the characteristic white matter

appearance on T1 images in many of our patients showingareas of more marked hypointensity In our study only fewof the participants had supratentorial atrophy which isprobably in part due to the fact that they were all com-paratively young

We hypothesize that the atypical MRI characteristics of pa-tient 201 could be attributable to 2 distinct conditions asmigration abnormalities have never been formally associatedwith POLR3-HLD34 Alternatively it is possible that it rep-resents the more severe end of the neurodevelopmentalspectrum Patient 202 the sister of patient 201 never un-derwent a brain MRI as she died in the neonatal periodHowever she had atypical clinical features including cardiacarrhythmias Cardiac anomalies are reported in several animalmodels and a few human cases of TCS2235 In addition 3patients were recently diagnosed with POLR1C-related

Figure 3 Pathogenic variants identified in POLR1C associated with POLR3-HLD

(AndashB) All reported pathogenic variants and their positions within the POLR1C gDNA (A) with missense variants represented in green in frame in orangetruncating in black splice site in purple and stop in red (B) (C) Missense variants displayed on the structure of the yeast ortholog of POLR1C (RPAC40)Variants previously identified in POLR3-HLD are represented in italic whereas newly identified variants are shown in bold The pLys295del is shown inorange The pThr26Ile pThr27Ala and pPro30Ser variants have not been represented because they are not visible in the crystal structure of RPAC40 (PDB5M5W)192038ndash40 POLR3-HLD = RNA polymerase III-related leukodystrophy

NeurologyorgNG Neurology Genetics | Volume 5 Number 6 | December 2019 9

disorder in 2 large studies applying whole-exome and whole-genome sequencing to unsolved genetic cases Their clinicalpresentation included cardiomegaly long QT syndrome andcardiomyopathy3637

In our cohort variants were diverse and distributed acrossPOLR1C Two participants carried the pArg279Gln variantpreviously associated with TCS16 patient 9 (compound het-erozygous with c69+1GgtA) and patient 13 (homozygous) Itwas initially thought that TCS and leukodystrophy disease-causing variants were distinct leading to abnormal localization ofPOLR1C in the nucleolus and abnormal assembly of the RNApolymerase III respectively15 However none of the individualscarrying the TCS pathogenic variant pArg279Gln showed signsof abnormal craniofacial development raising the questionwhether the specific genotype combination (compound het-erozygosity with pArg279Gln) is responsible for the presence orabsence of craniofacial abnormalities but not the pArg279Glnitself Alternatively a more complex mechanism than the pre-viously described selective defects in POLR1 or POLR3 could beinvolved We postulate that other factors such as geneticmodifiers and neonatal exposures influence the pathophysiologyPOLR1C-related disorders

This study provides a comprehensive description ofPOLR3-HLD caused by biallelic POLR1C pathogenicvariants based on the largest cohort of patients to date Wepresent patients with both a hypomyelinating leukodys-trophy and abnormal craniofacial development reminiscentof TCS suggesting a spectrum of clinical involvement inpatients with POLR1C-related disorder These results il-lustrate the expansion of a known phenotype in the field ofrare diseases

AcknowledgmentThe authors thank the patients and their families for theirparticipation They acknowledge Chiara Aiello PhD formolecular genetic contribution at the Unit of Neuromuscularand Neurodegenerative Disorders Laboratory of MolecularMedicine Bambino Gesu Childrenrsquos Hospital Rome Italy

Study fundingThis study was supported by grants from the CanadianInstitutes of Health Research (201610PJT-377869 MOP-G2-341146-159133-BRIDG) Fondation Les Amis drsquoElliotLeuco-Action Fondation Lueur drsquoEspoir pour Ayden Fon-dation le Tout pour Loo and Reseau de Medecine GenetiqueAppliquee of the Fonds de Recherche en Sante du QuebecThis research was enabled in part by support provided byCompute Canada (computecanadaca) The authors ac-knowledge the McGill University and Genome Quebec In-novation Center Dr Bernard has received the NewInvestigator Salary Award from the Canadian Institutes ofHealth Research (2017ndash2022) Dr Gauquelin has receivedgrants from the Canadian Gene Cure Advanced Therapies forRare Disease (Can-GARD) and from the RS McLaughlinand Teva Canada Innovation funds from the Faculty of

Medicine Universite Laval Dr Fribourg is supported byINSERM CNRS and the Universite de Bordeaux

DisclosureThe sponsors did not have any role in the design and conductof the study collection management analysis or interpretationof the data preparation review or approval of themanuscript ordecision to submit the manuscript for publication The DDDstudy presents independent research commissioned by theHealth Innovation Challenge Fund [grant number HICF‐1009‐003] a parallel funding partnership between Wellcome and theDepartment ofHealth and theWellcome Sanger Institute [grantnumberWT098051] The views expressed in this publication arethose of the author(s) and not necessarily those of Wellcome orthe Department of Health The study has UK Research EthicsCommittee approval (10H030583 granted by the CambridgeSouth REC and GEN28412 granted by the Republic ofIreland REC) The research team acknowledges the support ofthe National Institute for Health Research through the Com-prehensive Clinical Research Network This study makes use ofDECIPHER (deciphersangeracuk) which is funded by theWellcome Go to NeurologyorgNG for full disclosuresFunding information is provided at the end of the article

Publication historyReceived by Neurology Genetics April 23 2019 Accepted in final formSeptember 18 2019

Appendix Authors

Name Location Role Contribution

LaurenceGauquelinMD FRCPC

McGill UniversityMontreal CanadaThe Hospital for SickChildren Universityof Toronto TorontoCanada

Co-firstauthor

Design andconceptualized thestudy acquisition ofdata analyzed thedata and drafted themanuscript forintellectual content

Ferdy KCayami MD

VU UniversityMedical CenterAmsterdam TheNetherlandsCenter forBiomedicalResearchDiponegoroUniversitySemarang Indonesia

Co-firstauthor

Designed andconceptualized thestudy acquisition ofdata analyzed thedata and drafted themanuscript forintellectual content

LaszloSztriha MDPhD

University of SzegedSzeged Hungary

Author Acquisition of dataand revised themanuscript forintellectual content

Grace YoonMD FRCPC

The Hospital for SickChildren Universityof Toronto TorontoCanada

Author Acquisition of dataand revised themanuscript forintellectual content

Luan T TranMSc

McGill UniversityMontreal CanadaResearch Institute ofthe McGill UniversityHealth CenterMontreal Canada

Author Acquisition of dataand revised themanuscript forintellectual content

10 Neurology Genetics | Volume 5 Number 6 | December 2019 NeurologyorgNG

Appendix (continued)

Name Location Role Contribution

KetherGuerreroMSc

McGill UniversityMontreal CanadaResearch Institute ofthe McGill UniversityHealth CenterMontreal Canada

Author Acquisition of dataanalyzed the dataand revised themanuscript forintellectual content

FranccediloisHocke MD(cand)

CHU BordeauxBordeaux France

Author Acquisition of dataand revised themanuscript forintellectual content

Rosalina MLvanSpaendonkPhD

VU UniversityMedical CenterAmsterdam TheNetherlands

Author Acquisition of dataand revised themanuscript forintellectual content

Eva L FungMB ChB

The ChineseUniversity of HongKong Hong KongChina

Author Acquisition of dataand revised themanuscript forintellectual content

StefanoDrsquoArrigo MD

Fondazione IRCCSIstituto NeurologicoC Besta Milan Italy

Author Acquisition of dataand revised themanuscript forintellectual content

GessicaVasco MDPhD

Bambino GesuChildrenrsquos HospitalRome Italy

Author Acquisition of dataand revised themanuscript forintellectual content

IsabelleThiffaultPhD FACMG

Childrenrsquos MercyHospitals and ClinicsKansas City MOUniversity ofMissourindashKansas CitySchool of MedicineKansas City MO

Author Acquisition of datarevised themanuscript forintellectual content

Dmitriy MNiyazov MD

Ochsner for ChildrenNew Orleans LA

Author Acquisition of dataand revised themanuscript forintellectual content

RichardPerson PhDFACMG

GeneDxGaithersburgMaryland

Author Acquisition of dataand revised themanuscript forintellectual content

Kara StuartLewis MD

Phoenix ChildrenrsquosHospital Phoenix AZ

Author Acquisition of dataand revised themanuscript forintellectual content

EvangelineWassmerMD MSc

BirminghamChildrenrsquos HospitalBirmingham UnitedKingdom

Author Acquisition of dataand revised themanuscript forintellectual content

TrinePrescott MD

Telemark HospitalSkien Norway

Author Acquisition of dataand revised themanuscript forintellectual content

PennyFallonMBBSMRCPCH

St Georges UniversityHospital NHSFoundation TrustLondon UnitedKingdom

Author Acquisition of dataand revised themanuscript forintellectual content

MerielMcEntagartMD

St Georges UniversityHospital NHSFoundation TrustLondon UnitedKingdom

Author Acquisition of dataand revised themanuscript forintellectual content

Continued

Appendix (continued)

Name Location Role Contribution

Julia RankinMD PhD

Royal Devon andExeter Hospital NHSTrust Exeter UnitedKingdom

Author Acquisition of dataand revised themanuscript forintellectual content

RichardWebsterMBBS MScFRACP

The ChildrenrsquosHospital atWestmeadWestmead NewSouth WalesAustralia

Author Acquisition of dataand revised themanuscript forintellectual content

HeikePhilippi MD

Center ofDevelopmentalNeurologyFrankfurt Germany

Author Acquisition of dataand revised themanuscript forintellectualcontent

Bart van deWarrenburgMD PhD

Radboud UniversityMedical CenterNijmegen TheNetherlands

Author Acquisition of dataand revised themanuscript forintellectual content

DagmarTimmannMD

Essen UniversityHospital Universityof Duisburg-EssenEssen Germany

Author Acquisition of dataand revised themanuscript forintellectual content

Abhijit DixitMD

NottinghamUniversity HospitalsNHS TrustNottingham UnitedKingdom

Author Acquisition of dataand revised themanuscript forintellectual content

Claire SearleMB ChBMRCP

NottinghamUniversity HospitalsNHS TrustNottingham UnitedKingdom

Author Acquisition of dataand revised themanuscript forintellectual content

DDD Study Wellcome SangerInstitute WellcomeGenome CampusCambridge UnitedKingdom

Author Acquisition of dataand revised themanuscript forintellectual content

NiveditaThakur MD

University of TexasHealth ScienceCenter Houston TX

Author Acquisition of dataand revised themanuscript forintellectual content

Michael CKruer MD

Phoenix ChildrenrsquosHospital Phoenix AZArizona StateUniversity TempeAZ

Author Acquisition of dataand revised themanuscript forintellectual content

SuvasiniSharma MDDM

Lady HardingeMedical College andAssociated KalawatiSaran ChildrenrsquosHospital New DelhiIndia

Author Acquisition of dataand revised themanuscript forintellectual content

AdelineVanderverMD

Childrenrsquos Hospital ofPhiladelphiaPhiladelphia PAUniversity ofPennsylvaniaPhiladelphia PA

Author Acquisition of dataand revised themanuscript forintellectual content

DavideTonduti MDPhD

NeurologicalInstitute C BestaFoundation IRCCSMilan Italy

Author Acquisition of dataand revised themanuscript forintellectualcontent

NeurologyorgNG Neurology Genetics | Volume 5 Number 6 | December 2019 11

References1 Kevelam SH Steenweg ME Srivastava S et al Update on leukodystrophies a his-

torical perspective and adapted definition Neuropediatrics 201647349ndash3542 Vanderver A Prust M Tonduti D et al Case definition and classification of leuko-

dystrophies and leukoencephalopathies Mol Genet Metab 2015114494ndash5003 Parikh S Bernard G Leventer RJ et al A clinical approach to the diagnosis of patients

with leukodystrophies and genetic leukoencephelopathies Mol Genet Metab 2015114501ndash515

4 Steenweg ME Vanderver A Blaser S et al Magnetic resonance imaging patternrecognition in hypomyelinating disorders Brain 20101332971ndash2982

5 Schiffmann R van der Knaap MS Invited article an MRI-based approach to thediagnosis of white matter disorders Neurology 200972750ndash759

6 Wolf NI Vanderver A van Spaendonk RM et al Clinical spectrum of 4H leuko-dystrophy caused by POLR3A and POLR3B mutations Neurology 2014831898ndash1905

7 Bernard G Vanderver A POLR3-Related leukodystrophy In Adam MP ArdingerHH Pagon RA et al editors GeneReviews (R) Seattle University of WashingtonSeattle University of Washington Seattle GeneReviews is a registered trademark ofthe University of Washington Seattle All rights reserved 1993

8 La Piana R Tonduti D Gordish Dressman H et al Brain magnetic resonance imaging(MRI) pattern recognition in Pol III-related leukodystrophies J Child Neurol 201429214ndash220

9 Tetreault M Choquet K Orcesi S et al Recessive mutations in POLR3B encodingthe second largest subunit of Pol III cause a rare hypomyelinating leukodystrophyAm J Hum Genet 201189652ndash655

10 Bernard G Chouery E Putorti ML et al Mutations of POLR3A encoding a catalyticsubunit of RNA polymerase Pol III cause a recessive hypomyelinating leukodystro-phy Am J Hum Genet 201189415ndash423

11 Potic A Brais B Choquet K Schiffmann R Bernard G 4H syndrome with late-onsetgrowth hormone deficiency caused by POLR3Amutations ArchNeurol 201269920ndash923

12 Daoud H Tetreault M Gibson W et al Mutations in POLR3A and POLR3B area major cause of hypomyelinating leukodystrophies with or without dental abnor-malities andor hypogonadotropic hypogonadism J Med Genet 201350194ndash197

13 Gutierrez M Thiffault I Guerrero K et al Large exonic deletions in POLR3B genecause POLR3-related leukodystrophy Orphanet J Rare Dis 20151069

14 Dorboz I Dumay-Odelot H Boussaid K et al Mutation in POLR3K causes hypo-myelinating leukodystrophy and abnormal ribosomal RNA regulation Neurol Genet20184e289

15 Thiffault I Wolf NI Forget D et al Recessive mutations in POLR1C cause a leuko-dystrophy by impairing biogenesis of RNA polymerase III Nat Commun 201567623

16 Dauwerse JG Dixon J Seland S et al Mutations in genes encoding subunits of RNApolymerases I and III cause Treacher Collins syndrome Nat Genet 20114320ndash22

17 Jay JJ Brouwer C Lollipops in the clinic information dense mutation plots forprecision medicine PLoS One 201611e0160519

18 Gouy M Guindon S Gascuel O SeaView version 4 a multiplatform graphical userinterface for sequence alignment and phylogenetic tree building Mol Biol Evol 201027221ndash224

19 Tafur L Sadian Y Hoffmann NA et al Molecular structures of transcribing RNApolymerase I Mol Cel 2016641135ndash1143

20 DeLano WL Pymol an open-source molecular graphics tool CCP4 Newsletter OnProtein Crystallography 200282ndash92

21 Cayami FK Bugiani M Pouwels PJW Bernard G van der Knaap MS Wolf NI 4Hleukodystrophy lessons from 3T imaging Neuropediatrics 201849112ndash117

22 Katsanis SH Jabs EW Treacher Collins syndrome In Adam MP Ardinger HHPagon RA et al editors GeneReviews (R) Seattle University of Washington SeattleUniversity of Washington Seattle GeneReviews is a registered trademark of theUniversity of Washington Seattle All rights reserved 1993

23 Schlump JU Stein A Hehr U et al Treacher Collins syndrome clinical implicationsfor the paediatricianmdasha new mutation in a severely affected newborn and comparisonwith three further patients with the same mutation and review of the literature Eur JPediatr 20121711611ndash1618

24 Teber OA Gillessen-Kaesbach G Fischer S et al Genotyping in 46 patients withtentative diagnosis of Treacher Collins syndrome revealed unexpected phenotypicvariation Eur J Hum Genet 200412879ndash890

25 Vincent M Genevieve D Ostertag A et al Treacher Collins syndrome a clinical andmolecular study based on a large series of patients Genet Med 20161849ndash56

26 Ghesh L Vincent M Delemazure AS et al Autosomal recessive Treacher Collinssyndrome due to POLR1C mutations report of a new family and review of theliterature Am J Med Genet A 20191791390ndash1394

27 La Piana R Cayami FK Tran LT et al Diffuse hypomyelination is not obligate forPOLR3-related disorders Neurology 2016861622ndash1626

28 Minnerop M Kurzwelly D Wagner H et al Hypomorphic mutations in POLR3A area frequent cause of sporadic and recessive spastic ataxia Brain 20171401561ndash1578

29 Gauquelin L Tetreault M Thiffault I et al POLR3A variants in hereditary spasticparaplegia and ataxia Brain 2018141e1

30 Minnerop M Kurzwelly D Rattay TW et al Reply POLR3A variants in hereditaryspastic paraplegia and ataxia Brain 2018141e2

31 Bauer M Saldarriaga W Wolfe SA Beckwith JB Frias JL Cohen MM Jr Twoextraordinarily severe cases of Treacher Collins syndrome Am J Med Genet A 2013161A445ndash452

32 Kara B Koroglu Ccedil Peltonen K et al Severe neurodegenerative disease in brotherswith homozygous mutation in POLR1A Eur J Hum Genet 201725315ndash323

33 Paolacci S Li Y Agolini E et al Specific combinations of biallelic POLR3Avariants cause Wiedemann-Rautenstrauch syndrome J Med Genet 201855837ndash846

34 Jurkiewicz E Dunin-Wasowicz D Gieruszczak-Białek D et al Recessive mutations inPOLR3B encoding RNA polymerase III subunit causing diffuse hypomyelination inpatients with 4H leukodystrophy with polymicrogyria and cataracts Clin Neuroradiol201727213ndash220

35 Noack Watt KE Achilleos A Neben CL Merrill AE Trainor PA The roles ofRNA polymerase I and III subunits Polr1c and Polr1d in craniofacial developmentand in Zebrafish models of Treacher Collins syndrome PLoS Genet 201612e1006187

36 Farnaes L Hildreth A Sweeney NM et al Rapid whole-genome sequencing decreasesinfant morbidity and cost of hospitalization NPJ Genom Med 2018310

37 Eldomery MK Coban-Akdemir Z Harel T et al Lessons learned from additionalresearch analyses of unsolved clinical exome cases Genome Med 2017926

38 Fernandez-Tornero C Moreno-Morcillo M Rashid UJ et al Crystal structure of the14-subunit RNA polymerase I Nature 2013502644ndash649

39 Engel C Sainsbury S Cheung AC Kostrewa D Cramer P RNA polymerase Istructure and transcription regulation Nature 2013502650ndash655

40 Neyer S Kunz M Geiss C et al Structure of RNA polymerase I transcribing ribo-somal DNA genes Nature 2016540607ndash610

Appendix (continued)

Name Location Role Contribution

Marjo S vander KnaapMD PhD

VU UniversityMedical CenterAmsterdam TheNetherlands

Author Acquisition of dataand revised themanuscript forintellectual content

EnricoBertini MD

Bambino GesuChildrenrsquos HospitalRome Italy

Author Acquisition of dataand revised themanuscript forintellectual content

Cyril GoizetMD PhD

CHU BordeauxBordeaux France

Author Acquisition of dataand revised themanuscript forintellectual content

SebastienFribourgPhD

Universite deBordeaux BordeauxFrance

Author Acquisition of dataand revised themanuscript forintellectual content

Nicole IWolf MDPhD

VU UniversityMedical CenterAmsterdam TheNetherlands

Co-seniorauthor

Designed andconceptualized thestudy acquisition ofdata analyzed thedata revised themanuscript forintellectual contentand studysupervision

GenevieveBernard MDMSc FRCPC

McGill UniversityMontreal CanadaResearch Institute ofthe McGill UniversityHealth CenterMontreal Canada

Co-seniorauthor

Designed andconceptualized thestudy acquisition ofdata analyzed thedata revised themanuscript forintellectual contentand studysupervision

12 Neurology Genetics | Volume 5 Number 6 | December 2019 NeurologyorgNG

DOI 101212NXG000000000000036920195 Neurol Genet

Laurence Gauquelin Ferdy K Cayami Laacuteszloacute Sztriha et al pathogenic variants

POLR1CClinical spectrum of POLR3-related leukodystrophy caused by biallelic

This information is current as of October 30 2019

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