Bardet-Biedl Syndrome (BBS)

Bardet-Biedl syndrome occurs due to genetic changes (sometimes called mutations or pathogenic variants) in both copies of one of the BBS-related genes. 

Everyone inherits two copies of the BBS genes, one from each parent. When both parents have one copy of a non-working gene, they are carriers of BBS. Carriers do not have the disease, but when two carriers have a child, there is a 1 in 4 chance (25%) with each pregnancy that the child will have BBS. This pattern of inheritance is called autosomal recessive. When a person has pathogenic variants in both copies of a gene related to BBS, they develop the condition. 

BBS is typically diagnosed in childhood. The features of BBS can be different in different people with the condition, even those within the same family. Below is a summary of the most common features seen in BBS.  

Eyes 

• Vision loss starting in childhood due to retinal degeneration (dystrophy) 

Physical Features 

• Extra fingers or toes (polydactyly)

Growth & Development 

• Delays in meeting milestones such as walking or talking 
• Learning difficulties 
• Obesity, starting in infancy 

Organ Differences 

• Kidney Disease

Glands & Hormones (Endocrine) 

• Reduced amounts of sex hormones and infertility
• Genital differences

Additional Signs 

Other features may include:

• Differences in vision like eye misalignment (strabismus) or cataracts
• Type 2 diabetes
• Facial features such as down-slanting and widely-set eyes, large ears, or narrow forehead
• Abnormal heart structure (cardiac anomalies)
• Digestive system concerns including inflammatory bowel disease or structural differences

A doctor who specializes in BBS will complete an evaluation to confirm the diagnosis. It can be diagnosed using the clinical features listed above and is often confirmed with genetic testing. Genetic testing is done on a blood or saliva sample from the child. 

While there is no single treatment or cure for Bardet-Biedl syndrome at this time, there are treatments that can target specific symptoms, and researchers are also working on developing new therapies for BBS.

Treatment plans are created by a healthcare team with input from the patient and their family. Some symptoms may require more regular follow-up with specialists than others. The healthcare team will include your child’s pediatrician as well as specialists in:

• Genetics (geneticists)
• Kidney disease (nephrologists)
• Eye care (ophthalmologists)
• Glands and hormones (endocrinologists)
• Developmental and behavioral pediatrics

The management and treatment of the signs and symptoms of BBS may involve: 

• Medicines
• Management of diet and nutrition
• Medical procedures and/or surgeries
• Social support
• Work with speech, physical, and/or occupational therapists

Early intervention programs are a useful support resource to help address the developmental differences often seen in children with BBS. In many cases, children with BBS need extra support in school and would benefit from an individualized education program (IEP). Meeting and following up with a genetic counselor can help families better understand BBS and connect them with useful support resources. 

Our team works closely with researchers who study ciliopathies including BBS. Thus, we are informed of cutting-edge treatment and technology that may benefit the children in our care. We can connect interested children and families with opportunities to participate in research studies that can help us better understand BBS and possibly contribute to the discovery of future therapies. 

Bardet-Biedl syndrome can bring medical challenges and significant stress in the lives of those who know and love someone with the condition. The groups and research-based resources below can help provide support for families and those affected by BBS.

• Bardet-Biedl Syndrome Foundation
• Clinical Registry Investigating Bardet-Biedl Syndrome (CRIBBS)