Spectrum of pathogenic variants and high prevalence of pathogenic variants in Russian patients with Bardet-Biedl syndrome.

INTRODUCTION

Bardet-Biedl syndrome is a rare condition characterized by obesity, retinitis pigmentosa, polydactyly, development delay, and structural kidney anomalies. This syndrome has an autosomal recessive type of inheritance. For the first time, molecular genetic testing has been provided for a large cohort of Russian patients with Bardet-Biedl syndrome.

MATERIALS AND METHODS

Genetic testing was provided to 61 unrelated patients using an MPS panel that includes coding regions and intronic areas of all genes ( = 21) currently associated with Bardet-Biedl syndrome.

RESULTS

The diagnosis was confirmed for 41% of the patients ( = 25). Disease-causing variants were observed in , and genes In most cases, pathogenic and likely pathogenic variants were localized in , and genes; recurrent variants were also observed in these genes.

DISCUSSION

The frequency of pathogenic and likely pathogenic variants in the and genes among Russian patients matches the research data in other countries. The frequency of pathogenic variants in the gene is about 1.5%-2% of patients with Bardet-Biedl syndrome, while in the cohort of Russian patients, the fraction is 24%. In addition, the recurrent pathogenic variant c.1967_1968delinsC was detected in the gene. The higher frequency of this variant in the Russian population, as well as the lack of association of this pathogenic variant with Bardet-Biedl syndrome in other populations, suggests that the variant c.1967_1968delinsC in the gene is major and has a founder effect in the Russian population. Results provided in this article show the significant role of pathogenic variants in the gene for patients with Bardet-Biedl syndrome in the Russian population.