Multiple genetic mutations implicate spectrum of phenotypes in Bardet-Biedl syndrome

Bardet-Biedl syndrome (BBS) is a clinically and genetically heterogeneous ciliopathy with several clinical features including retinitis pigmentosa, obesity, kidney dysfunction, postaxial polydactyly, behavioral dysfunction and hypogonadism with wide spectrum of additional features. With multiple phenotypes and heterogeneous distribution, it is unlikely that BBS is caused by single gene defect. We have performed clinical and genetic diagnosis of two individuals from an Indian family with classical BBS symptoms. Whole exome sequencing identified homozygous missense mutation in BBS10 gene, hemizygous missense AR and homozygous missense PDE6B mutations in the proband and affected sibling with BBS. Identification of BBS10 mutation along with AR and PDE6B gene mutation will expand the genetic and phenotypic spectrum in individuals with BBS.