Two novel variants in a Bardet-Biedl syndrome type 5 patient with severe renal phenotype.

Bardet-Biedl syndrome type 5 (BBS5) has never been reported in Chinese populations. The aim of this study is to report the first BBS5 case in China, explore the phenotype and genotype correlation. The case was male, Han nationality, born with polydactyly and gained weight after birth, accompanied by polydipsia, polyuria and nocturia. He was found to have low vision at the age of 7 years, and having insufficient renal function at the age of 20 years. After hospitalization, he was found to have suffered from atrophy of the whole layer of macular retina, and end stage of kidney disease, presenting with shrinking and cyst-like changes of bilateral kidneys. Whole-exome sequencing was performed among the proband and his parents (Trios), further validated using Sanger sequencing and quantitative polymerase chain reaction. Two novel compound heterozygous variants of BBS5 gene [a missense variant NC_000002.12, NM_152384.3:c.1A>G(p.Met1?) & a large deletion c.(?-60)(386 + 1_387-1)del] were detected. BBS is rare, whereas BBS5 is rarer. Herein, we reported a Chinese BBS5 patient with severe renal phenotype and identified two novel BBS5 variants.