Natural History of Weight Gain in Children With Bardet-Biedl Syndrome: Results From CRIBBS

Background: Bardet-Biedl syndrome (BBS) is a rare genetic disease associated with early-onset severe obesity. Current understanding of weight gain patterns among those with BBS aged 3 to 17 years is limited. Methods: We analyzed data obtained in 2014 to 2021 from the Clinical Registry Investigating Bardet-Biedl Syndrome (CRIBBS), an international registry of individuals with BBS. Children 3 to 17 years who had ≥1 BMI assessment were selected. Anthropometric measures such as BMI and self-reported use of weight-loss medications or diets were assessed. Obesity status was assessed by the percentage of the 95th percentile for body mass index and classified on severity accordingly. Results: A total of 331 children with BBS were included (mean age: 8.7y; 51% males). At the first CRIBBS assessment (baseline), 9% had overweight and 81% had obesity (class I, II, III: 26%, 24%, 31%). Among children with any baseline obesity, 151 children reported ≥2 weight measurements >2 years apart and were included in the weight change analyses. Over a mean of 3.5y (range 2-8y), 36% (n=54) of these children had class III obesity at baseline, with 32% each in obesity classes I and II. Overall, 68% of children with obesity and 76% of those with class III obesity at baseline did not improve by the last assessment >2 years later (i.e., remained in the same obesity class or advanced to a higher obesity class). Weight loss interventions were reported in 30% of children with class III baseline obesity and only 23% of all children. Conclusions: Children with obesity, particularly those with Class III obesity, were found to be highly prevalent in this large sample of children with BBS. Over a mean of 3.5y, the majority of children who had obesity continued to have it or experienced worsening weight gain. Successful weight loss was rarely achieved despite nearly 25% of children utilizing weight-loss interventions. This analysis provides further evidence on the early-onset severity of obesity in children with BBS and need for effective interventions.