Morphological andneurochemical Pelizaeus-Merzbacher...

J. Neurol. Neurosurg. Psychiat., 1965, 28, 540

Morphological and neurochemical study ofPelizaeus-Merzbacher disease1

B. GERSTL, N. MALAMUD, R. B. HAYMAN, AND P. R. BOND

From the Laboratory Service, Veterans Administration Hospital, Palo Alto, California, and Departmentof Pathology, Stanford University School of Medicine, and the Neuropathology Service, Langley Porter

Neuropsychiatric Institute, San Francisco, California

Of the various types of demyelinating disorder,Pelizaeus-Merzbacher disease (Pelizaeus, 1885;Merzbacher, 1910) is probably the rarest and leastunderstood form. For while its genetic, clinical, andpatho-anatomical features have been fairly welldelineated, the underlying biochemical disturbancethus far has been only incompletely analysed. Con-sequently the pathogenesis of the disorder has re-mained unclear and controversial.

Three main hypotheses have been advanced as tothe manner in which the changes are produced,viz., through destruction or removal of myelin,similar to that in multiple sclerosis (Spielmeyer,1923); through faulty or incomplete formation ofmyelin that undergoes progressive degeneration andthus is considered to be a form of leucodystrophy(Bielschowsky and Henneberg, 1928; Poser and vanBogaert, 1956; Seitelberger, 1963); and througharrest of myelination at an early age (Blackwood andCumings, 1954; Zeman, Demyer, and Falls, 1964).The purpose of this investigation is to report the

patho-anatomical findings in a case of Pelizaeus-Merzbacher disease, and through a detailed chemicalanalysis of the fixed brain tissue, contribute to thechemical pathology of the disease.

CASE REPORT

HISTORY R.F., a 13-year-old white boy, had a normalbirth with the exception of bilateral congenital cataracts.His birth weight was 6 lb. 2 oz. and his height was 20inches. Up to the age of 6 months his development pro-ceeded normally and by that time he more than doubledhis birth weight, weighing 14 lb. 12 oz. But from the age of6 months on he showed signs of increasing physical andmental retardation. His body weight and height remainedvirtually stationary so that by the age of 31 years hisweight was only 17 lb. and height 29 inches. There was amarked degree of microcephaly. He displayed no signs ofintelligence or interest in his surroundings, had no senseof balance, did not learn to walk or talk, and gradually'This study was supported by grant No. NB-03821 of the NationalInstitute of Neurological Diseases and Blindness, U.S. Public HealthService.

developed marked contractures of the lower extremities(further details of his clinical course were lacking).He suffered frequently from upper respiratory infectionsand ultimately expired of bronchopneumonia.The family history showed that an older brother

suffered from the same condition and died at the age of22 years (there is, however, no record of a necropsyhaving been performed). A sister, age 15, is living and isapparently normal.

POST-MORTEM FINDINGS The general necropsy findingswere bilateral bronchopneumonia and pulmonaryoedema; hypoplasia of the thyroid and pituitary glands;undescended atrophic testes, and general underdevelop-ment of the skeleto-muscular system.The brain weighed 500 g., being reduced by more than

50% of normal size (Fig. 1). The cerebral hemisphereswere symmetrical and their convolutional pattern wasnormally outlined, showing no undue evidence ofatrophy. The brain-stem was proportionately small butthe cerebellum was diffusely and severely atrophied. Theoptic nerves were also bilaterally atrophic, especially theone on the right.

Coronal sections (Fig. 2) disclosed a normal amount ofgrey but a marked reduction of the white matter whichexhibited a mottled greyish-white appearance. Both thecentral and gyral white matter was bilaterally and equallyinvolved throughout all the lobes. There was also atrophyof the corpus callosum, anterior commissure, internal andexternal capsules, cerebral peduncles, the base of thepons, and the medullary pyramids. By contrast, the basalganglia appeared normal with the exception of moderateatrophy of the thalamus and brownish pigmentation ofthe globus pallidus. In the brain-stem, the normal ap-pearance of the tecto-tegmental structures contrastedwith atrophy of the base. The most severe and widespreadatrophy was encountered in the cerebellum. where boththe grey and white matter was equally involved. Theentire ventricular system was widely and symmetricallydilated. (The spinal cord was not available for examin-ation.)

Microscopically, the grey matter of the entire brainshowed a normal cytoarchitecture and, with the excep-tion of terminal oedema, there were no significant altera-tions in either the nerve cells, myelin content, or glialelements. The only abnormalities in the grey matter weresevere and widespread degeneration of the Purkinje

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Morphological and neurochemical study ofPelizaeus-Merzbacher disease

FIG. 1. External appearance, showing small size of brain,and severe atrophy ofcerebellum as well as of optic nerves,especially on the right side.

T-x1.

FIG. 2. Coronal section, showing diffuse reduction qf allparts of the white matter that has a vaguely mottledappearance.

FIG. 3. Section of cerebrum,showing tigroid pattern of demye-lination because of preservedislands of myelin: Luxolfast blue-periodic-acid Schiff stain.

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B. Gerstl, N. Malamud, R. B. Hayman, and P. R. Bond

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FIG. 4. Histology of demyelinating process showing de-myelinated area (above), containing a few oligodendrogliaand scattered fibrillary astrocytes contrasting with normalmyelin island (below) in which the normal number ofoligo-dendroglia is present. Luxol fast blue-periodic acid Schiffstain x 150.

and granular cells of the cerebellum with secondarydegeneration of mild to moderate degree in the inferiorolives, dentate nuclei, and thalamus. The globus palliduscontained moderate amounts of calcareous deposits inthe walls of blood vessels.The principal histological change was noted in the

white matter (Fig. 3). It took the form of irregularlyalternating foci of demyelination and normal myelina-tion, the latter inconstantly related to blood vessels,resulting in a striking tigroid appearance. This was mostconspicuous in the white substance of the cerebral hemi-spheres of all lobes, but was also present in the corpuscallosum, anterior commissure and fornix; the capsulesand cerebral peduncles; the more densely myelinatedparts of the basal ganglia, such as the thalamus and globuspallidus (Fig. 4); the brain-stem and cerebellum, wherethere were often admixtures of the primary changes withsecondary tract degeneration.The demyelinating foci (Fig. 5) were characterized

histologically by paucity of oligodendroglia and mildproliferation of fibrillary astrocytes in cresyl violetpreparations, by dense gliosis in Holzer preparations,and by relative preservation of axis cylinders with theBielschowsky method. Microglial and gitter cell reactionwas minimal and inflammatory response was lacking.The staining affinities of the myelin breakdown prod-

ucts were as follows: Sudan IV showed rare sudanophilicdroplets, diffusely scattered in the demyelinating foci and

in perivascular spaces of both the latter and themyelinatedareas. Sudan black gave a negative reaction. WithP.A.S. there was a positive reaction in granules of thefew gitter cells and reacting astrocytes. Alcian blue gave anegative reaction, as did metachromasia.

SUMMARY OF CLINICOPATHOLOGICAL FINDINGS

Clinically, the case reported here presented the classicfeatures of the disease, despite the meagre data,namely, the familial background and the apparentsex-linked inheritance, occurring in two male sib-lings; the early onset at the age of 6 months; and thechronic course. In addition, the clinical signs ofmicrocephaly, dwarfism, mental retardation, andprogressive development of contractures, althoughin themselves not pathognomonic, have been re-ported in other cases.The case exhibited the characteristic pathology

of Pelizaeus-Merzbacher disease, namely, the wide-spread involvement of the white matter, the tigroidpattern of demyelination, the absence of abnormaldecomposition products, the sudanophilia, thoughmild, of myelin breakdown, the intense gliosis and thepreservation of axis cylinders. The only significantdegeneration of grey matter was noted in the cere-bellum, a finding common to many of the leuco-dystrophies and most commonly attributed to anassociated convulsive disorder, not known in thiscase because of the incomplete history.

NEUROCHEMICAL STUDIES

MATERIALS AND METHODS The brain tissue had beenfixed in formalin for one year. The most importantformalin-induced chemical changes are the loss of phos-pholipids, particularly plasmalogens, and an increase inwater content (Davison and Wajda, 1962; Rodnight,1957). Plasmalogens, therefore, were not estimated inthis investigation.Grey and white matter were dissected carefully. In

view of the smallness of the myelinated areas in theatrophic white matter, it was not feasible to separategrossly myelinated from non-myelinated areas. Extrac-tion of formalin-fixed tissues by the Folch method is notas complete as with fresh material. The Folch extraction(Folch, Lees, and Sloane Stanley, 1957), therefore, wasfollowed by a Soxhlet extraction with Bloor's mixtureand subsequently with chloroform-methanol, each forsix hours. This accomplished near complete removal oflipids as evidenced by the additional yield of only 0-12-0-15% lipid phosphorus on further Soxhlet treatment ofspecimens of control no. 1 and the Pelizaeus-Merzbacherbrain.Water content, lipid phosphorus, carboxyl esters, total

fatty acids, and cholesterol were estimated as in previousinvestigations (Gerstl, Tavaststjerna, Hayman, Smith, andEng, 1963) and galactolipids and sulphatides by themethods of Radin, Brown, and Lavin (1956) and Davisonand Gregson (1962), respectively. The procedures for

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separation and quantification of hydroxy fatty acidshave been reported in detail elsewhere (Eng, Lee, Hay-man, and Gerstl, 1964). A relatively large amount offree fatty acids was present in all formalin-fixed samples,as found on thin-layer chromatography. These wereextracted with petroleum-ether:diethylether 60:40 and,for the purpose of gas liquid chromatography, methy-lated. Identification and quantification of individual fattyacids was accomplished by gas liquid chromatography asdescribed earlier (Gerstl et al., 1963). Brain proteins wereestimated by determination of total amino-acids withninhydrin after hydrolysis with 6N HCl according tothe method of Rosen (1957).

Regrettably, a control brain of similar age could not beobtained. Thus, two brains of patients, aged 52. and 62,which also had been kept in formalin for one year,were used as controls. For the purpose of comparison,chemical data on two unfixed brains from normalchildren, 18 and 48 months of age, were also obtained.

RESULTS Lipid data on various areas of cortex ofthe Pelizaeus-Merzbacher brain, two adult and twochildren's brains, are given in Table I. The watercontent of the formalin-fixed was slightly higher thanthat offresh material, but was similar in the Pelizaeus-Merzbacher and the control brains. Likewise, lipidphosphorus, carboxyl esters, and total cholesteroldid not exhibit any difference between the Pelizaeus-Merzbacher and the adult control brains. The totallipids, including the free fatty acids, in the Pelizaeus-Merzbacher case, were slightly less than in the con-trols. The amount of cerebrosides, however, on theaverage, was less than one-half of that in the adultcontrol brains. Since it has been established thatcerebrosides and cholesterol are not altered duringformalin fixation over a period of two years (Rod-night, 1957), the data for cerebrosides represent truevalues. The total hydroxy fatty acids in two samplesof the Pelizaeus-Merzbacher grey matter were about

one-half of the amount found in the adult controls;in the third specimen, even less. This corresponds tothe low cerebroside content.The amounts of lipid phosphorus, carboxyl

esters, and total fatty acids found in the greymatter of the two unfixed children's brains weregreater than those in the adult and Pelizaeus-Merzbacher brains, which may be due to absenceof fixation. As to compounds not affected by forma-lin, the cerebrosides and cholesterol in these threebrains were present in similar concentrations.Sulphatide levels in the Pelizaeus-Merzbacherbrain and in the 18-month-old child's brain weresimilar and one-half that in the cortex of the adultbrain no. 1.

In the white matter of the Pelizaeus-Merzbacherbrain, the water content was higher (Table II) andthe amount of lipid phosphorus, cholesterol,carboxyl esters, and total fatty acids was about one-third of that in the adult controls; that of the cere-brosides, including the sulphatides, and of the totalhydroxy fatty acids, however, was only one-fifth,or less. The concentration of cholesterol, cerebro-sides, and sulpholipids was also diminished whencompared with that found in the two children'sbrains.The analysis by gas liquid chromatography of the

regular fatty acids of the grey matter (Table III)revealed little if any difference between the Pelizaeus-Merzbacher and the control brains as far as thesaturated acids are concerned. The amounts ofmono-unsaturated acids of chain length C20 to C26 were,however, one-half the amount found in the controls.

In the white matter (Table III) all types of fattyacids were at levels lower than in the two controls,and this was particularly marked in the instance ofthe long chain mono- and polyunsaturated acids.

TABLE ILIPIDS OF GREY MATTER1

Water Lipid Carboxyl Fatty Cholesterol(%) Phosphorus Esters AcidsBrain

Galactose Sulphatides Total 2-HydroxyFatty Acids

Pelizaeus-MerzbacherFrontal lobe 87-0Parietal lobe 859Occipital lobe 85 5

Control no. IFrontal lobe 84-8Parietal lobe 84-8

Control no. 2Frontal lobe 86-2Temporal lobe 84-0Occipital lobe 84-6

17 months 83-448 months

Frontal lobe 86-2Temporal-parietal lobe 84-5Occipital lobe 85 0

- Not done"Expressed in mM/l00 g. wet weight

2-74 3-54 5-06 2-05 0-122-94 3-73 6-16 2-32 0-23 12-76 3-94 5-79 2-21 0-20 f

3-17 4-72 7-78 2-33 0-52 13-25 479 8-10 2-61 0-54 f

242 331 626 1912 77 4 14 7 40 2 502 92 3 78 7 43 2-38451 679 820 258

043088065037

0 0390 074

0 13

062

4.00 696 848 208 0 18 -

4 03 6-97 8 30 2 12 0 13 -

425 7 18 929 230 0 16 -

0080210-18035040

033048

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TABLE IILIPIDS OF WHITE MAlTER'

Water Lipid Carboxyl Fatty Cholesterol(%) Phosphorus Esters AcidsBrain

Galactose Sulphatides Total 2-HydroxyFatty Acids

Pelizaeus-MerzbacherFrontal lobeTemporal lobeOccipital lobe

Control no. IFrontal lobeParietal lobe

Control no. 2Frontal lobeTemporal lobeOccipital lobe

18 months48 months

Frontal lobeTemporal-parietal lobeOccipital lobe- Not done

86-6 2-66 3 75 6-12 2-53 0 79847 3-08 4-27 769 3-44 1-29 X84-4 2-96 4-36 7-07 307 0-83 f 0-21

71-5 8-11 9 90 20-20 8-59 5-19 0-9771-3 8-21 9-98 20-09 9 99 4-87 -

70-8 8-18 9-95 22-90 10-3371-2 8-01 9-68 22-55 10-3570 7 7-32 9-21 21-50 9-1471-4 8-98 11-60 19-86 9 39

77 3 8-0874-8 9*5475-3 8-86

11-88 17-02 8-3413-14 20 65 10-0312-73 18-69 9-18

5-63 1-075-32 1-055-58 1-143*59 033

3 17 -

5 07 0-633-72 -

'Expressed in mM/100 g. wet weight

TABLE IIIFATTY ACIDS IN WHITE AND GREY MATTER1

Brain 12:0-18:0 20:0-26:0

Grey matterPelizaeus-Merzbacher

Frontal lobeTemporal lobeOccipital lobe

Control no. IFrontal lobeParietal lobe

Control no. 2Frontal lobeParietal lobeOccipital lobe

White matterPelizaeus-Merzbacher

Frontal lobeTemporal lobeOccipital lobe

Control no. IFrontal lobeTemperal lobe

Control no. 2Frontal lobeTemporal lobeOccipital lobe

3 193903.59

4-294-21

3-464.574-73

3.953703-42

6-907-19

7-818-088-26

0-02003003

0O050-06

0030040-06

0-080-240-08

0520-41

0-510-60045

14:1-18:1

1-391-601-55

2-152-13

1-322-031-59

1-792-041-83

6-146-93

7-156-88635

20:1-26:1

0030-070-07

0-180-16

0-110-120-15

0-180550-24

2562-49

2-652-472-38

PUFA

0-290-29026

0-88077

0-150-230-31

0-280-420-24

1-571-88

1 661-220-69

'Expressed in mM/100 g. wet weight

Small amounts of free fatty acids have been foundin fresh brain tissue (Rouser, Galli, Kritchevsky,Lieber, and Heller, 1964; Rowe, 1964), but the pres-ence of large amounts of free fatty acids is ap-parently the result of the exposure to formalin(Jatzkewitz, 1964). They amounted to 20 to 30%of the total fatty acids in the grey matter of thePelizaeus-Merzbacher brain, and 26 to 33% in thecontrols; the corresponding figures for the whitematter were 17-0 to 215%, and 18-5 to 21-5% forthe Pelizaeus-Merzbacher and control brains, re-

spectively. Also, the percentage distribution of the in-dividual acids did not reveal any significant difference.

Gas liquid chromatography of the hydroxy fattyacids (Table IV) revealed a higher percentage ofC16:0 and C18:0 acids in the grey matter of thePelizaeus-Merzbacher brain than in the controls,while the distribution of the longer chain acids was

similar and corresponds to that given by O'Brien,Fillerup, and Mead (1964) for those of the combinedcerebrosides and sulphatides. No essential differencein the percentage distribution was observed for thewhite matter (Table V).

Quantitative estimation of proteins revealed a

slightly lower protein content of the Pelizaeus-Merzbacher brain (Table VI).

0-36054045

2-182-45

2-662592-880-98

1-501-681-66

Odd Total

0030-060-10

009006

0-100-110o10

0070-190-10

0-380-72

0520-640 54

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TABLE IVPERCENTAGE COMPOSITION OF HYDROXY FATTY ACIDS IN GREY MATTER1

Adult Brain Formalinjfixed 13- Year Brain Formalin-fixed

Control no. IFattyAcid Total Grey

14:0 -15:0 0-415:1 0-616:0 0 316:1 -17:0 0-217:1 0 418:0 1-318:1 -19:0 1*220:0 0-620:1 0-221:0 0-221:1 -22:0 7-122:1 0-623:0 17-123:1 1 424:0 29-724:1 22-125:0 5-625:1 5-326:0 1-026:1 4-1- Not found'Expressed in Mole %

Control no. 2

Frontal Lobe Temporal Lobe Occipital Lobe

090-60*5

0-60 3150-23-41 40-20-20 37-40415-709

29 519 75.75 2153-6

070704

040-21 5043-1090404047-40.1

16-115

32-217-76-14-8143 1

1 30-8

05031-60-32-6100403047-2

14-91-3

27-021 95 65.41-14-4

Pelizaeus-Merzbacher

Frontal Lobe Temporal Lobe Occipital Lobe

3-85.7092-74-3

0-50-8

1I16-4075.53.5

30-611-15 14-70-63-4

1.01*409

0*50-23-30-53-2190 30-80.18-00-614 8

1 531 915-75*23-71.03*1

0-56-7

0-55.43-7

5.42-7

7-10 714-71-4

26-99-85-13-4164-2

PERCENTAGE COMPOSITION

Formalin-fixed

TABLE VOF HYDROXY FATTYFresh 17-MonthBrain

ACIDS IN WHITEFresh 48-MonthBrain

MATTER1

Pelizaeus-Merzbacher BrainFormalin-fixed

14:0 -15:0 -15:1 -16:0 Trace16:1 -17:0 0-217:1 -18:0 1-018:1 -19:0 Trace20:0 0320:1 -21:0 0 121:1 0422:0 6-222:1 0-223:0 15-723:1 0-824:0 40-224:1 19-625:0 6-625:1 3.526:0 1*226:1 4-4- Not found'Expressed in Mole

DISCUSSION

PATHO-ANATOMICAL FEATURES For a detailed ac-count of the historic development of the concept ofPelizaeus-Merzbacher disease, the reader is referred

to the recent paper by Zeman et al. (1964). However,certain questions raised by the latter deserve furthercomment.

Following the consideration by Bielschowsky andHenneberg (1928) of Pelizaeus-Merzbacher disease

545

Fatty Adult BrainAcid

Fresh

TraceTraceTrace

0-1Trace1.0

0.102

TraceTrace7-20-21700 5

36-923-45.43-2I *23.5

1-1

050-61 407070-5

040-2

11-7

13-104

49 111-53.5090-62-3

0.5TraceTrace0-2Trace0.1Trace09TraceTrace04

Trace0 38-0041280-6

47.914 85.31.9174-2

Trace04030-2

0-30-51 5

1 50-60-2070-28-70313-509

33-817-76-64-42-24-8



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Brain

TABLE VIPROTEIN CONTENT OF FORMALIN-FIXED BRAIN1

White Matter Grey Matter

Pelizaeus-MerzbacherFrontal lobeTemporal lobeOccipital lobe

Control no. IControl no. 2- Not done'Expressed in g./100 g. wet weight

9.39-610-312-3102

as a form of leucodystrophy, implying faulty myelinmetabolism, the condition has been classified as a

'neutral fat' leucodystrophy (Poser and van Bogaert,1956) or as a 'sudanophil' leucodystrophy (Seitel-berger, 1960; Norman, 1962; Peiffer, 1962). Underthe latter designation, a heterogeneous collectionof conditions with varied clinical, genetic, andneuropathological findings has been included. Thus,Peiffer (1962) classified four different subtypes:(1) simple orthochromatic leucodystrophy; (2)classical Pelizaeus-Merzbacher disease; (3) Seitel-berger type; and (4) adult type, which was firstdescribed by Lbwenberg and Hill (1933). The cri-teria of a leucodystrophy were present in all, namely,a diffuse, non-focal degenerative familial disorderbut, in contrast to other leucodystrophies, the myelinbreakdown involved normal (sudanophil) decompo-sition products. Our case resembled the classicalPelizaeus-Merzbacher form in its genetic, clinical,and morphological aspects.Zeman et al (1964) have objected to the designa-

tion of the disorder as a sudanophil leucodystrophy.In their opinion, the process is substantially a dis-turbance of myelinogenesis taking place early inlife, probably before birth. They differ, however,from Blackwood and Cumings (1954) who proposedthat myelination is arrested at a chronological ageof 2 years. Relying on their findings in three cases ofthe Seitelberger type, dying in early childhood,Zeman et al (1964) point to the complete lack ofmyelin stainability in their cases as evidence of faultymyelination rather than demyelination. They see inthis an expression of an intense genetic defectoperating in cases of younger age. By contrast, thecases dying during adult life show the characteristicpatchy lack of myelin stainability as a result of aprobable milder genetic defect. On the basis of theseobservations, the authors would exclude a numberof cases reported in the literature that differ fromtheirs in genetic, clinical, or patho-anatomicalmanifestations. Such a view, in our opinion, wouldseem unwarranted, especially since our knowledge ofthe nature of the metabolic defect is still inadequate.In agreement with others, we feel that the sparsesudanophil breakdown products merely reflect theunusually slow progress of the degenerative process

and this is substantiated by the intense reactivegliosis.

BIOCHEMICAL FEATURES In the grey matter of thePelizaeus-Merzbacher brain (Table I), the concen-tration of cerebrosides including sulphatides, as wellas the mono-unsaturated long chain fatty acids, wasreduced. This was paralleled by a deficit of hydroxyfatty acids and indicates that, in contrast to thefindings in 'normal areas' of multiple sclerosis, thephrenosine-type of cerebrosides is afflicted inPelizaeus-Merzbacher disease. Blackwood and Cum-ings (1954) also reported a deficit of cerebrosides,but their findings of reduced concentrations ofcholesterol and phospholipids could not be cor-roborated.

In the white matter (Table II), there was a markeddeficit of all lipids; however, that of the cerebrosidesexceeded the others. It should be noted that thecontrol tissues contained approximately 15% lesswater so that on a dry weight basis the differences inthe values would be correspondingly less, however,not detracting from the significance of the alteredlipid spectrum. The findings on the white matter areat variance with those of Zeman et al. (1964), whostated that relatively high concentrations of cerebro-sides and cholesterol are found in Pelizaeus-Merz-bacher white matter. They also called attentionto the lack of correspondence between myelinstainability and amounts of lipids still present. Thismay be explained by the fact that only about 50%of the total lipids are components of myelin proper(Autilio, Norton, and Terry, 1964; Gerstl, Tavastst-jerna, Hayman, Eng, and Smith, 1965).

If destruction and removal of myelin were theonly processes underlying the pathology of Peli-zaeus-Merzbacher disease, the amounts of lipidsabsent from the tissue should reflect their propor-tions in purified myelin. These have been reportedas 47, 57, and 57-6 %, respectively, for phospholipids,cholesterol, and galactolipids (Autilio et al., 1964).A similar point can be made concerning the un-substituted fatty acids, the long chain membersbeing deficient to a greater extent than those ofC14 to C18 chain length. These observations would bealso difficult to reconcile with arrest of myelinationas assumed by Blackwood and Cumings (1954).Seitelberger's hypothesis (1960, 1963) of an inherentdisorder of glycerophosphatides could not be testedsince those compounds were largely destroyed byformalin fixation.The metabolism and synthesis of the fatty acid

and galactose moieties of the cerebrosides have beenfairly extensively studied. Fulco and Mead (1961)came to the conclusion that C24 :0 is the precursorof cerebronic acid, while Bernhard, Hany, Hausheer,

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and Pedersen (1962) suggested that alpha-hydroxyacids are not formed from unsubstituted precursors.The average percentage of lignoceric acid in fivecontrol samples of white matter was 1 81, but wasonly 0 89 (average) in the three specimens of thePelizaeus-Merzbacher white matter. The percentageof cerebronic acid, however, was similar in bothPelizaeus-Merzbacher and control specimens. Thus,the data presented here would support the suggestionof Bernhard et al. (1962).As to the pathogenesis of Pelizaeus-Merzbacher

disease, one would have to postulate that thesynthesis of cerebrosides, including that of bothsubstituted and non-substituted long-chain fattyacids, as well as the incorporation of galactose intothe galactolipids by microsomes (Burton, Sodd, andBrady, 1958), are impaired. The cerebrosides withtheir long-chain fatty acids are probably essentialfor the intactness and cohesiveness of the myelinstructure (Vandenheuvel, 1963; O'Brien, 1964). Theirnear absence in Pelizaeus-Merzbacher disease couldwell be one of the factors initiating or permittingadditional changes, including removal of otherlipids, e.g., phospholipids and cholesterol, in-adequately incorporated into the myelin structure.

SUMMARY

The clinicopathological findings in a case of Peli-zaeus-Merzbacher disease are reported and theliterature is discussed.

Chemical analysis of the formalin-fixed braintissue revealed diminished concentrations of cere-brosides and cerebroside sulphates in the grey matter.This was associated with a deficit of long-chainmono-unsaturated unsubstituted fatty acids. In thewhite matter there was a decrease of all lipids, butthe depletion of the cerebrosides, including sulpha-tides, and long-chain mono- and poly-unsaturatedfatty acids exceeded that of other lipids. The amountof cerebrosides in the Pelizaeus-Merzbacher brainwas less than in that of the two brains of children,aged 18 and 48 months.

Pathogenetically, neither general arrest norremoval in myelin would account for all the changes.Inadequate or faulty synthesis of cerebrosides as theprimary chemical pathology would be the mostsatisfactory explanation.

REFERENCES

Autilio, L. A., Norton, W. T., and Terry, R. D. (1964). The prepara-tion and some properties of purified myelin from the centralnervous system. J. Neurochem., 11, 17-27.

Bernhard, K., Hany, A., Hausheer, L., and Pedersen, W. (1962).Inkorporation von 14C-Acetat in die Fettsauren der Cere-broside des Rattengehirnes. Helv. chim. Acta, 45, 1786-1794.

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