Bardet-Biedl syndrome
Bardet-Biedl syndrome (BBS) is a rare autosomal recessive ciliopathy with a highly variable phenotype that evolves significantly during childhood and/or adolescence.28,29 It’s estimated that as many as 2500 people in the United States are living with BBS.25 Obesity and hyperphagia are two common features of BBS that can seriously impact the overall health and quality of life of these patients.28,29
“It’s a constant need to eat. And that’s when she started sneaking foods... We ended up getting some locks and putting them on our pantry and on the fridge.”
Olivia, whose daughter Adalissa is living with BBS
Common features
BBS has a highly variable phenotype that evolves significantly during childhood and/or adolescence.
Phenotype can vary between siblings.
Pathology
Obesity and hyperphagia in BBS:
Likely driven by impairment of a key signaling pathway that regulates hunger57
The MC4R pathway1,57
- Plays a key role in regulating hunger, satiety, and energy expenditure
- Is activated by leptin, a neurosignaling hormone generated in adipose tissue
Take a deeper look inside the MC4R pathway
Hyperphagia in BBS
Hyperphagia is a key symptom associated with obesity in BBS and often has an early onset, typically by age 5.4
General dimensions of hyperphagia23
Behavior
Excessive food-seeking behavior
Drive
Preoccupation with food
Severity
Significant distress when denied food
Patients with BBS suffer from hyperphagia, exhibiting extreme food-seeking behavior.4
Total hyperphagia score and subscale scores in 13 patients with BBS*

Adapted from Sherafat-Kazemzadeh R et al. Pediatr Obes. 2013;8(5):e64-e67.
Hyperphagia and food-seeking behavior are different in BBS
Individuals living with BBS have significantly greater hyperphagia scores overall (total) and in the behavioral dimension compared to matched controls.
*A hyperphagia questionnaire assessing 13 patients with BBS and 23 nonsyndromic controls with similar age, sex, and BMI z-score. After adjustment for age, sex, race, and BMI z-score, total score (P=0.032) and behavior subscale (P=0.003) remained significantly different.
Consider the Understanding the Impact of Hyperphagia tool for discussions with individuals living with BBS and their families.
Obesity in BBS
As many as 9 out of 10 patients with BBS are affected by obesity.29
BMI z-scores by gender and age group in children with BBS (n=628)46

Severe obesity has an early onset, typically beginning in childhood by age 5, and persists into adulthood46
Obesity further complicates management of comorbidities.
Diabetes
Renal
impairment
Hypertension
Chronic obesity and hyperphagia management are challenging in patients with BBS.
Diet and behavioral modifications
Diet and exercise are not always enough when living with a rare genetic disease of obesity like BBS
Pharmacotherapies
Not all treatments target the MC4R pathway, a root cause of obesity and hunger in people living with BBS57
Bariatric surgery
May be complicated due to associated comorbidities
Listen to Dr. Robert Haws discuss hyperphagia and obesity in BBS
Resources
Videos
Pathway deficiencies in BBS
Searching for answers
The Role of the MC4R Pathway
Downloads
MC4R=melanocortin-4 receptor; POMC=proopiomelanocortin.