Bardet-Biedl Syndrome: A Study of the Renal and Cardiovascular Phenotypes in a French Cohort

Background and Objectives Bardet-Biedl Syndrome (BBS) is a rare autosomal recessive ciliopathy with a wide spectrum of clinical features including obesity, retinitis pigmentosa, polydactyly, mental retardation, hypogonadism, and renal abnormalities. The molecular genetic profile of BBS is currently being investigated after the recent identification of 14 BBS genes involved in primary cilia-linked disease. This study aims to characterize the renal and cardiovascular presentations and to analyze possible relationships between genotypes and clinical phenotypes.

Design, setting, participants & measurements This clinical study was performed in a national cohort of 33 BBS patients, 22 men and 11 women, all aged >16 years (mean age 26.3 years).

Results Renal abnormalities, including impairment of renal function and signs of chronic interstitial nephropathy of dysplastic nature, were documented in 82% of the patients. Cardiovascular evaluations revealed that this group of young patients had significant cardiovascular risk factors. Hypertension was found in >30% of the patients and hyperlipidemia in >60%, and almost 50% had other metabolic abnormalities. Overt diabetes was present in only 6%. With regard to genotype-phenotype correlation, patients with a mutation in the BBS6, BBS10, or BBS12 gene (10 of 33 patients) had more severe renal disease.

Conclusions Our study results confirm the frequent occurrence of renal involvement in patients with BBS, underscore the high risk of cardiovascular disease in these patients, and provide new information on a possible genotype-phenotype correlation.