A case series of Bardet-Biedl syndrome in a large Turkish family and review of the literature

Abstract

Background and aim: Bardet-Biedl syndrome (BBS) is a rare autosomal recessive genetic disorder. We aimed to report a case series of Bardet-Biedl syndrome in a Turkish family and review the literature.

Patients and methods: This family had 3 females and 4 males, totally 7 alive; 2 children (1 female and 1 male) had died. Parents were consanguineous. The first was a birth of twins and female sibling of these twins had congenital anal atresia and died when she was three-month old. Third (30 yr), 4th (28 yr) and 9th (19 yr) alive siblings were obese, blind and diabetic. We detected truncal obesity, postaxial polydactyly, cognitive impairment and hypogonadism. Rod-cone dystrophy was detected in ophthalmic examination. With these typical clinical findings, BBS was diagnosed. There was also a male member of the family which shared the same features of his affected brothers but he had died while he was eight months old. Marked glycosuria was determined and urine density was 1021 g/cm3. There was not any further endocrinological abnormality. Fasting blood glucose levels were changing between 290 and 452 mg/dl and the last glycated hemoglobine levels (A1c) were 9.3%, 11.2% and 12.8%, respectively. Diabetes mellitus and obesity were treated with diet, exercise, multiple daily insulin injections and metformine at the dose of 2000 mg/d.

Conclusions: Although it is an infrequent condition due to autosomal recessive transmission, consanguineous marriage may increase the risk of emergence of BBS. Genetic counseling is a very important issue in the family of patients with BBS, in order to prevent new cases.