ABSTRACT
BACKGROUND: Posterior polar cataract is a clinically distinctive opacity located at the back of the lens. It is commonly acquired in age related cataract, and may infrequently occur in pedigrees with congenital cataract. To date, five loci for autosomal dominant congenital posterior polar cataract have been identified. These include two genes, CRYAB and PITX3, on chromosomes 11q and 10q respectively, and three loci with as yet unknown genes on chromosomes 1p, 16q and 20p. PURPOSE: To find the chromosomal location of a gene causing autosomal dominant congenital posterior polar cataract in three Moroccan Jewish families. METHODS: A whole genome scan was performed using microsatellite markers spaced at approximately 10 cM intervals. For fine mapping, five additional microsatellite markers were genotyped. Two-point lod scores were calculated using MLINK software, from the LINKAGE program package. After linkage was established, several positional candidate genes were assessed by PCR based DNA sequencing. RESULTS: The new cataract locus was mapped to an 11.3 cM interval between D14S980 and D14S1069 on chromosome 14q22-23. A maximum two point lod score of 5.19 at theta = 0 was obtained with the markersD14S274. The positional and functional candidate genes SIX1, SIX4, SIX6, OTX2, and ARHJ were excluded as the cause of cataract in these families. CONCLUSION: An as yet unidentified gene associated with posterior polar cataract maps to the long arm of chromosome 14q22-23.
Subject(s)
Cataract/epidemiology , Cataract/genetics , Chromosomes, Human, Pair 14 , Jews , Adult , Cataract/diagnostic imaging , Child , Child, Preschool , Chromosome Mapping , Female , Genetic Linkage , Homeodomain Proteins/genetics , Humans , Lod Score , Male , Middle Aged , Morocco/epidemiology , Morocco/ethnology , Otx Transcription Factors/genetics , Pedigree , Phenotype , Radiography , Trans-Activators/genetics , rho GTP-Binding Proteins/geneticsABSTRACT
In some muscular dystrophies there is ocular involvement characterized by blepharoptosis and ophthalmoplegia. These conditions occur in chronic progressive external ophthalmoplegia, oculopharyngeal muscular dystrophy, mitochondrial myopathy, myotonic dystrophy, and ocular myasthenia, among others. Although they differ in their systemic clinical manifestations and in genetic inheritance, ocular involvement is common to all of them. Manifestations include bilateral progressive blepharoptosis with or without extraocular muscle malfunction. During surgical repair of the ptotic eyelid, consideration must be given to eyeball movements, in addition to maximal eyelid elevation, and to avoiding overcorrection and consequent corneal overexposure, leading to dryness and visual impairment. With these muscular dystrophic disorders, resection of the levator muscle or blepharoplasty alone does not suffice. Follow-up shows that most patients need a secondary repair after a short while. Operative correction uses a frontalis sling for eyelid elevation and support. A series of 8 patients with these diseases, operated on by various surgical techniques during the past 7 years, is presented.
