Homozygou Null Mutation in the ABCA4 Gene in Two Familie With Autoomal Receive Retinal Dytrophy Original Reearch Article

Purpoe To identify the gene cauing autoomal receive retinal dytrophy in Indian familie and to characterize the aociated phenotype. Deign Experimental and obervational. Method Familie with autoomal receive nonyndromic retinal dytrophie were recruited. Complete ophthalmic evaluation, including viual acuity, viual field, fundu examination, and electroretinography, wa performed on all member. Genotyping of 14 familie for two or more microatellite marker flanking each of 21 different gene cauing retinal dytrophy wa done by tandard method to creen for the preence of homozygoity by decent. Mutational creening of the ABCA4 gene wa carried out on 18 member (five affected) of two familie by amplification and direct automated equencing of exon and flanking equence. equence alteration identified were teted for coegregation with dieae in the familie and for preence in 100 unrelated normal control. Reult Two of 14 familie howed homozygoity hared by affected individual for marker flanking the ABCA4 locu. A homozygou nonene mutation in the ABCA4 gene of Arg2030top wa found in one family and a homozygou ingle bae deletion leading to framehift at Arg409 wa found in the econd family. Both of thee mutation were found to coegregate with dieae. Five affected individual from the two familie had early-onet viual lo, diminihed rod and cone electroretinographic repone, and widepread atrophy of the retinal pigment epithelium. Concluion Homozygou null mutation in ABCA4 produced a evere widepread retinal degeneration that howed marked central retinal involvement.