• Mutations in cornea-specific keratin K3 or K12 genes cause Meesmann corneal dystrophy. Irvine AD, Corden LD, Swensson B, Moore JE, Frazer DG, Smith FJD, Knowlton RG, Christophers E, Rochels R, Uitto J. McLean WHI* Nature Genet 1997; 16:184-187.

THE INTERMEDIATE FILAMENT CYTOSKELETON OF

corneal epithelial cells is composed of cornea-specific keratins K3 and K12. Meesmann corneal dystrophy (MCD) is an autosomal dominant disorder causing fragility of the anterior corneal epithelium, where K3 and K12 are specifically expressed. The authors postulate that dominant-negative mutations in these keratins might be the cause of MCD. K3 was mapped to the type II keratin gene cluster on 12q and K12 to the type I keratin gene cluster on 17q using radiation hybrids. The authors obtained linkage to the K12 locus in Meesmann original German kin­dred and showed that the phenotype segregated with either the K12 or the K3 locus in two Northern Irish pedigrees. Heterozygous missense mutations in K3 (E509K) and in the K12 (V143L; R135T) completely cosegregated with MCD in the families. They were not found in 100 normal conserved keratin helix boundary motifs, where dominant mutations in other keratins have been found to severely compromise cytoskeletal function, leading to keratinocyte fragility phenotypes. The authors conclude that they have demonstrated for the first time the molecular basis of Meesmann corneal dystrophy. — Thomas J. Liesegang

*Epithelial Genetics Group, Department of Dermatology and Cutaneous Biology, Jefferson Medical College, 233 S 10th Street, Philadelphia, PA 19107.

• Prevalence of uveitis in an outpatient juvenile arthritis clinic: outset of uveitis more than a decade after onset of arthritis. Akduman L, Kaplan HJ, Tychesen L*. J Pediatr Opthalmol Strabismus 1997;34:101-106.

THE AUTHORS' OBJECTIVE WAS TO DETERMINE THE

prevalence and severity of uveitis in an outpatient pediatric arthritis clinic in the midwestern United States during the 1990s. They studied retrospectively the prevalence and clinical characteristics of all

children diagnosed with arthritis at Shriner's Hospital for Crippled Children and followed by the pediatric rheumatology and ophthalmology units of the St Louis Children's Hospital between 1992 and 1995. Seven children (9%) developed uveitis in a popula­tion of 78 patients with juvenile arthritis. Six of the seven children were female, and all six females had antinuclear antibody (ANA)-positive, juvenile rheu­matoid arthritis (JRA). The prevalence of anterior uveitis in females with ANA-positive, pauciarticular JRA was 20% and in polyarticular JRA, 17%. One of the girls with uveitis had combined JRA and sarcoid-osis; the boy with uveitis had juvenile spondylitis. Arthritis preceded the onset of uveitis in each child by 1 to 13 years. Progression of the uveitis in three of the children resulted in band keratopathy and cata­ract, causing significant visual loss in two (29%) of the children who developed uveitis. The authors conclude that the prevalence and ocular morbidity of uveitis in juvenile arthritis appears to have remained relatively stable over the past 2 decades. Onset of the uveitis in several of the children in the study popula­tion occurred more that a decade after the diagnosis of arthritis. Girls with ANA-positive JRA and boys with juvenile spondylitis may need to be followed up with periodic slit-lamp examination for longer periods than previously recommended. — Thomas J. Liese­gang

*St. Louis Children's Hospital (Room 2s89), Washington University School of Medicine, One Childrens Place, St. Louis, MO 63110.

• The effect of high and low Dk/L soft contact lenses of the glycocalyx layer of the corneal epitheli­um and on the membrane associated receptors for lectins. Latkovic S, Nilsson SEG*. CLAO J 1997;23:185-191.

B ACTERIAL ADHERENCE OR BINDING TO THE TARGET

cell is a prerequisite for the initial stage of most infections and seems to be mediated by lectin-like ligands on the bacterial surface and specific receptors on the target cell membrane. The authors studied whether contact lens wear under closed eye condi­tions changes the glycocalyx layer, whether it exposes more lectin receptors than eye closure without a contact lens, and whether wear of low oxygen trans-

VOL. 124, NO. 5 ABSTRACTS 717

missibility (Dk/L) contact lenses exposes more recep­tors than high Dk/L contact lenses. The eyes of six rabbits under general anesthesia were fit with either a high Dk/ L soft contact lens or a low Dk/L soft contact lens or were left without a lens as control. All eyes were kept closed by suture for 24 hours. After removal of the contact lenses, all corneas were excised, put in glutarahdehyde for fixation, rinsed, incubated with plant-derived lectins (wheatgerm agglutin [WGA]) conjugated with gold particles, and prepared for electron microscopy. Membrane associ­ated gold particles were counted, and the results were processed statistically. After 24 hours of lens wear under closed eye conditions, the glycocalyx showed physical changes in the form of thinning or compres­sion and signs of biochemical changes reflected as an increase in number of WGA receptors. The average number of membrane associated gold particles per 750 |A length of corneal epithelium were significantly (P < .001) more numerous after wear of high Dk/L contact lenses and after wear of low Dk/L contact lenses compared to controls; the figure after wear of low Dk/L contact lenses was significantly (P < .01) higher than the figure after wear of high Dk/L contact lenses. The authors conclude that lens wear under closed eye conditions changes the corneal glycocalyx layer physically as well as biochemically. Significantly larger numbers of WGA receptors were exposed after contact lens wear than without a contact lens. Significantly more receptors were exposed after wear of low Dk/L contact lenses than after wear of high Dk/L contact lenses and may influence the risk of bacterial keratitis. — Thomas J. Liesegang

*Department of Ophthalmology, Linkoping University, SE-58185, Lin-koping, Sweden.

• Autosomal dominant cerebellar ataxia with reti­nal degeneration (ADCA II): clinical and neuro-pathological findings in two pedigrees and genetic linkage to 3pl2-p21.1. Jobsis GJ*, Weber JW, Barth PG, Keizers H, Baas F, van Schooneveld MJ, van Hilten JJ, Troost D, Geesink HH, Bolhuis PA. J Neurol Neurosurg Psychiatr 1997;62:367-371.

THE CLASSIFICATION OF AUTOSOMAL DOMINANT

cerebellar ataxias (ADCA) distinguishes cerebel­

lar ataxia with pigmentary retinal degeneration as a distinct category, namely ADCA type II or, more recently, spinocerebellar ataxia (SCA) 7. Recently, ADCA II (SCA7) has been mapped to chromosome 3p. The authors studied 16 patients from two pedi­grees fulfilling the ADCA II criteria. Ataxia was constant in all age groups, and there was evidence of both upper and lower motor neuron involvement. In patients with late adult onset, the disease started with cerebellar symptoms, with visual failure caused by retinal degeneration a late symptom, appearing as long as 17 to 27 years after the onset of ataxia. In an intermediate group with adult onset disease (between 20 and 40 years), manifest retinopathy was preceded by ataxia. In the youngest generation (younger than 10 years), visual failure preceded ataxia. The ophthalmoscopic appearance was usually that of a finely granular pigmentation in the macular area with slight pallor of the optic disk. In later stages, the retina showed brownish pigment mottling and pale optic disks. An extinguished electroretinogram was found in four of five cases. External ophthalmoplegia, ac­companied by ptosis in only a minority, was present in 11 patients. Young onset of ADCA II correlated with disease severity and progression. Strong antici­pation was found in subsequent generations, suggest­ing that the mutation of ADCA II, as in ADCA I, consists of an expanded CAG trinucleotide repeat. Genetic linkage to chromosome 3pl2-p21.1 was confirmed. — Nancy J. Newman

*Department of Neurology (H2-214), Academic Medical Center, PO Box 22700, 1100 DE Amsterdam, The Netherlands.

• The diagnostic evaluation and multidisciplinary management of neurofibromatosis 1 and neurofi-bromatosis 2. Gutmann DH*, Aylsworth A, Carey JC, Korf B, Marks J, Pyeritz RE, Rubenstein A, Viskochil D. JAMA 1997;278:51-57.

N EUROFIBROMATOSIS 1 (NF1) ANDNEUROFIBROMATO-

sis 2 (NF2) are autosomal dominant genetic disorders in which affected individuals develop both benign and malignant tumors at an increased fre­quency. Other features of NF1 include vision loss, learning disabilities, and skeletal problems, while cataract formation and hearing loss are associated

718 AMERICAN JOURNAL OF OPHTHALMOLOGY NOVEMBER 1997