Bardet-Biedl syndrome

Changes in certain genes can cause Bardet-Biedl syndrome. These changes might be new or passed down from parents to children. Many different gene changes can result in BBS. Even though a lot has been learned about the genes linked with the condition, it’s not fully understood how changed genes cause specific symptoms. Sometimes, healthcare professionals diagnose BBS based on symptoms because they can’t find changes in genes.

BBS may be inherited in an autosomal recessive way. This means that each parent passes on one changed gene to the child.

Parents can pass down to their children the changes in genes that cause Bardet-Biedl syndrome.

Complications of Bardet-Biedl syndrome can include:

• Extra weight gain. Most people with BBS have extra body weight by the time they are 3 to 5 years old. This continues into adulthood. The extra body weight can affect health and limit the ability to do daily activities.
• Long-term kidney disease and loss of kidney function. Changes in how the kidneys develop and function can cause long-term kidney conditions. Extra body weight and diabetes raise the risk of developing kidney disease. Some people develop end-stage renal disease, which results in the kidneys not being able to filter waste and toxic substances from the body and get rid of them in urine.
• Vision loss and blindness. Rods and cones are the cells in the eye that are important for sight. These light-sensitive cells, called photoreceptors, are on the tissue at the back of the eye. This tissue is called the retina. With BBS, these rods and cones are slowly destroyed over time, a condition called retinal degeneration. Vision loss occurs in almost all people with BBS and often starts in early childhood. The first symptom may be trouble seeing in low light. Low vision, but not total blindness, usually happens around 15 years of age.
• Hormone imbalances. Changes in hormone balance can affect growth and development. Changes in development of the sex organs before birth, including the testicles and ovaries, can affect the hormones that cause puberty.
• Other health conditions. Having BBS can raise the risk of other medical conditions, such as diabetes, high blood pressure, high cholesterol, fatty liver disease, poor coordination and obstructive sleep apnea.
• Learning disabilities. Speaking, learning, thinking and memory can be affected and can impact daily functioning and independence.
• Behavioral issues and mental health conditions. Autism spectrum disorder is common. Other conditions can include depression, obsessive-compulsive disorder, anxiety, hyperactivity and behavior challenges.

If you have Bardet-Biedl syndrome, these tips can help. If your child has BBS, you can help your child to:

• Learn about Bardet-Biedl syndrome. Get accurate information, support and encouragement.
• Create healthy eating habits. Healthy eating habits are important for the body to work well and to prevent extra weight gain and related health conditions. Use meal planning to have nutritious meals and snacks at expected times. Try plating food before sitting down to eat. Put extra food away to make taking seconds less automatic. Plan for outings and special events. To lessen eating outside of meal or snack time, try keeping food out of sight and place locks or alarms on food cabinets and the refrigerator.
• Prevent safety issues. For low vision or blindness, make sure that the home, daily activities and outings are set up to stay safe. Without a sense of smell, odors such as smoke, a natural gas leak or spoiled food can’t be identified. Place special detectors to alert for smoke and natural gas, and use a special food labeling and dating system.
• Get regular physical activity and exercise. These can help build muscle strength and motor skills and support a healthy weight.
• Learn what support is available. For example, ask about early intervention programs for babies and young children. Ask about special education services at school. Look for behavioral and mental health services, if needed. Find support services for low vision or blindness.
• Keep regular follow-up appointments with healthcare professionals. This can help prevent future issues.

If your primary healthcare professional thinks that you or your child has Bardet-Biedl syndrome, you’ll likely be referred to a doctor who specializes in conditions that affect hormones, called an endocrinologist.

You might want to take a friend or family member with you to the appointment to help you remember information.

Before your appointment, make a list of:

• Symptoms and when they started. Include anything that makes the symptoms worse or better.
• All medicines, vitamins, herbs and other supplements. Include the doses.
• Family history, such as whether anyone in your family has Bardet-Biedl syndrome.
• Treatment for conditions related to BBS, if any. Include what the treatment was and if it helped.
• Any other medical conditions and their treatments.
• Areas of life affected by the condition. These may include, for example, vision, weight or education. Think about what information, tools or services would be helpful.
• Questions to ask your healthcare professional.

Questions to ask may include:

• What likely is causing the symptoms?
• What kinds of tests are needed?
• Are other medical specialists needed?
• What treatments do you recommend?
• Are there things to do at home to help?
• There are other health conditions. Are they part of Bardet-Biedl syndrome?
• Are any limits needed?
• What services are available to help with care?
• Are there print materials or websites that you’d suggest to help me learn more about BBS?

Feel free to ask other questions during your appointment.

What to expect from your doctor

Your healthcare professional may ask you questions, such as:

• What are the symptoms? When did you first notice them?
• Has anyone else in your family been diagnosed with Bardet-Biedl syndrome?