The Role of BBS1 in an Ethnically Diverse Canadian Population with Bardet–Biedl Syndrome.

Abstract

Abstract: : Purpose: Bardet–Biedl syndrome (BBS) is an autosomal recessive multi–systemic disorder. BBS ultimately leads to blindness due to severe retinitis pigmentosa. BBS is genetically heterogeneous and mutations in BBS1 are proposed to account for the majority of cases. We aim to determine the role of BBS1 (OMIM; 209901) in an ethnically diverse Canadian population with Bardet–Biedl syndrome. Methods: Patients diagnosed with BBS were recruited from the Hospital for Sick Children and the Northwest Territories. Patients were screened for mutations in all 17 coding exons of BBS1. Mutation screening was performed by a combination of single strand conformational polymorphism analysis (SSCP) and direct sequencing. M390R, the most common BBS1 mutation was specifically assessed by restriction enzyme digestion (BspHI). Results: Prevalence of BBS1 mutations in our cohort was less than previously reported. The M390R mutation had an allele frequency of only 6% in our cohort. This is much less than described by previous studies (23 – 35%). M390R was only observed in patients of British ancestry. Novel changes including F534A and a homozygous R160Q were identified. Conclusions:BBS1 and specifically its M390R change do not appear to play a major role in Bardet–Biedl syndrome in the population studied. This is in contrast to previous studies describing BBS1 as the major BBS disease gene. This distinction is likely due to the diverse ethnicity of our patient cohort compared to those previously examined.

Keywords: gene screening • genetics • mutations