Investigation of Four Genes Responsible for Autosomal Recessive Congenital Cataract and Highly Expressed in the Brain in Four Unrelated Tunisian Families

Manèl Chograni,Faouzi Maazoul,Habiba Chaabouni Bouhamed,Myriam Chaabouni

doi:10.4236/ojoph.2012.23014

Abstract

Purpose: To identify the causative gene for phenotypes associating autosomal recessive congenital cataract, mental retardation and congenital cataract, mental retardation and microcephaly in four unrelated Tunisian families. Methods: Four genes (EPHA2, GALK1, GCNT2, and CRYBB1) were selected based on expression in human brain and their known or putative function. Linkage analyses were performed for the four genes in multiple affected and unaffected families’ members and results were explored by the GeneMapper ID v3.2 software. Results: No linkage was identified for the four studied genes in the four families. Affected members of each family did not share common haplotypes in corresponding candidate regions containing selected gene. Conclusion: Although the four studied genes were reported responsible for autosomal recessive congenital cataract and highly expressed in the human brain, we report no linkage for EPHA2, GALK1, GCNT2, and CRYBB1 genes in four families with congenital cataract, mental retardation and congenital cataract, mental retardation and microcephaly.

Highlights

Congenital cataracts are one of the major causes of vision loss in children worldwide and are responsible for approximately one third of blindness in infants [1]
Conclusion: the four studied genes were reported responsible for autosomal recessive congenital cataract and highly expressed in the human brain, we report no linkage for EPHA2, GALK1, GCNT2, and CRYBB1 genes in four families with congenital cataract, mental retardation and congenital cataract, mental retardation and microcephaly
Segregation analysis using the polymorphic markers on chromosome 1 for EPHA2, on chromosome 17 for GALK1, on chromosome 6 for GCNT2 and on chromosome 22 for CRYBB1 within minimum 10-cM region allowed us to exclude implication in studied phenotypes of all regions analyzed seeing that the affected members and their parents did not share a common haplotype

Summary

Introduction

Congenital cataracts are one of the major causes of vision loss in children worldwide and are responsible for approximately one third of blindness in infants [1]. Nonsyndromic congenital cataracts have an estimated frequency of 1 to 6 per 10,000 live births. They vary markedly in severity and morphology, affecting the nuclear, cortical, polar, or subcapsular parts of the lens or, in severe cases, the entire lens, with a variety of types of opacity. Few autosomal recessive cataract loci have been mapped. 13 loci residing on chromosomes 1p34.4-p32.2, 1q21.1, 3p22-24.2, 6p23-24, 9q13-22, 16q21-22, 19q13, 19q13.4, 20p12.1, 21q22.3, 22q11, 22q12.1 and 17q, have been mapped, with six of these causing autosomal dominant cataracts [3,4,5,6,7,8,9,10,11,12]

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Results

Conclusion