Implication of the ABCR Gene in Autosomal Recessive Cone-rod Dystrophies (CRD)

Abstract

Abstract: : Purpose: To evaluate the implication of the ABCR gene in thirty unrelated families affected with autosomal recessive cone-rod dystrophy (CRD). Methods: The 50 exons of the ABCR gene were screened for mutations using Denaturing High Pressure Liquid chromatography (DHPLC) and direct sequencing in one patient of each family of our series. Results: Among the thirty families screened, only five were studied by linkage analyses and were indeed linked to the STGD1 locus on chromosome 1p22.1. The remaining families were directly screened for ABCR gene mutations. So far, only a few mutations have been identified in some patients affected with autosomal recessive CRD. The nature of these mutations confirmed the genotype-phenotype correlations previously reported. Conclusion: These results are discordant from those published by Maugeri et al in 2000 which emphasized that the ABCR gene was the major gene responsible for CRD. It is however possible that some patients of our series born to unrelated parents could be compound heterozygous for large deletions in the ABCR gene, non-detectable by the mutation screening methods using PCR amplification. This hypothesis will be checked by semi-quantitative PCR. The whole study will be presented.

Keywords: 562 retinal degenerations: hereditary • 335 candidate gene analysis • 420 genetics