Endocrine Abstracts

Introduction

Bardet–Biedl syndrome (BBS) is a rare autosomal recessive ciliopathy characterized by rod-cone dystrophy, learning difficulties, polydactyly, obesity, genital malformations, and renal abnormalities. We report the case of a young patient followed for this syndrome, which is revealed by early obesity.

Observation

This is a 23-year-old patient from a consanguineous marriage with a personal history of well-substituted peripheral hypothyroidism. Received in consultation for obesity. the history revealed excessive weight gain and an eating disorder such as polyphagia and active search for food. On clinical examination, the patient presented with pronounced obesity with a body mass index (BMI) of 37.2 kg/m2, BP = 160/100 mmHg, deformation of the fingers of the hands and feet type axial polydactyly, syndactyly and brachydactyly. There is a difficulty in adapting to the dark followed by a gradual decline in visual acuity, retinitis pigmentosa in the fundus. Cardiovascular: Arterial hypertension well controlled under ARB 2 with normal heart echo. Renal: Moderate renal failure with an estimated renal clearance of 53.9 ml/min, ultrasound shows bilateral renal atrophy with loss of cortico-medullary differentiation. the Patient was put under hygieno-dietetic rules with a monitoring protocol.

Discussion

Despite normal birth weight, most individuals with BBS experience rapid weight gain in early childhood, with high rates of overweight/obesity sustained through adolescence. The diagnosis of SBB is retained in the face of obesity associated with polydactyly, retinitis pigmentosa and renal impairment. The obesity observed in our patient is almost constant and genetic, early and difficult to treat. Although the mechanisms for obesity in BBS remains incompletely understood, disruption of the hypothalamic leptin- melanocortin signaling pathway is evident. THe molecular mechanistic pathways leading to renal disease in BBS remain unelucidated. It has been suggested that aberrant mTOR signaling may contribute to the development of cystic kidney disease. Another theory proposes that ciliary dysfunction leads to aberrant non-canonical Wnt signaling and planar cell polarity, which may contribute to the development of cysts. At least 25 causative genes have been identified in BBS. Previous reports document that truncating variants in BBS genes predict greater risk for severe chronic kidney disease and increased cardiovascular disease markers compared to missense variants.

Conclusion

Obesity and renal failure are common manifestations in the autosomal recessive Bardet–Biedl (BB) syndrome. Bardet–Biedl syndrome is currently treated symptomatically focusing in particular on aggressive management of diabetes, hypertension, and metabolic syndrome