Bardet Biedl Syndrome: Causes, Symptoms, and Treatment
Medically reviewed by Achuta Uppu, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Bardet Biedl Syndrome?
A geneticist (a doctor for inherited conditions) helps confirm it, an ophthalmologist (an eye doctor) follows the vision loss, and an endocrinologist (a hormone doctor) treats weight and hormone problems. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is Bardet-Biedl syndrome?
Bardet-Biedl syndrome is a rare genetic condition that affects many parts of the body. Its features vary greatly from person to person.
The main features are vision loss, obesity, extra fingers or toes, kidney problems, learning problems, and low levels of sex hormones. Severity varies, even within the same family.
Symptoms
The main signs include:
- Vision loss. The light-sensing tissue at the back of the eye (the retina) wears out over time. Night vision problems often start in childhood, then blind spots appear. Most people become legally blind by their teen years or early adulthood.
- Obesity. Weight gain usually starts in the first years of life and lasts a lifetime. Fat builds up around the belly and chest, not the arms and legs.
- Extra fingers or toes (polydactyly).
- Kidney abnormalities, which can be serious or life-threatening.
- Learning problems and intellectual disabilities.
- Low levels of sex hormones (hypogonadism) and trouble having children.
Other features can include slow speech, delayed motor skills like standing and walking, anxiety and mood problems, and genital abnormalities. Some people have dental problems, short or fused fingers or toes, loss of smell, or heart, liver, and digestive problems.
Causes and who gets it
It is caused by disease-causing changes in at least 26 different genes, often called the BBS genes. These genes help the cilia work. Cilia are tiny projections on most cells. They pass signals from outside the cell to the inside. When they fail, many body systems are affected.
About 23% of cases come from the BBS1 gene and 15% from the BBS10 gene. In 20 to 30% of people, the cause is unknown. It is inherited in an autosomal recessive pattern: a child must get a changed gene from both parents. Parents carry one copy but have no symptoms. It affects males and females equally, about 1 in 100,000 people in North America and Europe.
How doctors diagnose it
Doctors diagnose BBS by its main features: vision problems from retinal dystrophy (a broken-down retina), belly-centered obesity, extra digits, and other signs. Because features vary, some patients go without a clear diagnosis for years.
An ophthalmologist (eye doctor) can test the eyes. An electroretinogram (ERG) measures the retina's electrical response to light. Genetic testing may help confirm it, but it may not be covered by insurance.
Treatment
There is no cure. Treatment focuses on each person's symptoms. Care often needs a team of specialists.
Weight control is a key part of care. Doctors recommend an active lifestyle, plus diet and exercise plans and help from a dietitian. High cholesterol and diabetes are treated as they are in other people. In 2022, the FDA approved setmelanotide (Imcivree) for weight management in patients 6 and older with obesity due to BBS.
An eye doctor watches the eyes and corrects vision problems. There is no proven cure for the retinal dystrophy. Patients with low hormone levels may get supplements. Surgery can fix extra digits and some genital or heart defects. A kidney transplant may be needed for severe kidney disease. Anesthesia needs special care. Airway changes can make it harder to keep the airway open.
When to see a doctor
See a doctor if a child has night vision problems, extra fingers or toes, steady weight gain in infancy, or learning problems. Get care right away for sudden changes in vision or a serious kidney problem, such as blood in the urine. Undescended testicles need treatment because they raise the risk of testicular cancer.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. This doctor can follow weight, blood pressure, and diabetes over time. The doctor can also coordinate specialists and track kidney and hormone care.
Common questions
Is Bardet-Biedl syndrome inherited?
Yes, usually in an autosomal recessive pattern. A child must get a changed gene from both parents. Parents carry one copy but have no symptoms.
What causes the vision loss?
The retina, the light-sensing tissue at the back of the eye, wears out over time. Night vision problems start in childhood, then blind spots. Most people become legally blind by their teen years or early adulthood. No proven cure exists for the retina problem.
Is there a medicine for the weight gain?
Yes. In 2022, the FDA approved setmelanotide (Imcivree) for weight management in patients 6 and older with obesity due to BBS. Diet and exercise programs are also recommended.
Can it be prevented?
It is a genetic condition, so it cannot be prevented. Genetic counseling can help families understand the chance of passing it on.
Sources
- MedlinePlus Genetics - Bardet-Biedl syndrome
- National Organization for Rare Disorders - Bardet-Biedl Syndrome
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
