Rare Classroom: Bardet-Biedl Syndrome

Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The disease that we will be learning about today is:

Bardet-Biedl Syndrome

What is Bardet-Biedl Syndrome?

  • Bardet-Biedl Syndrome is a rare genetic disorder with highly variable symptoms which may include retinal degeneration, obesity, reduced kidney function, and polydactyly (extra digits of the hands or feet) among many other features.​
  • BBS affects less than 3,000 individuals in the U.S. Because it is so rare, BBS may not be recognized early.​
  • There is no cure for Bardet-Biedl syndrome.
  • BBS is officially a “rare disease” affecting approximately 1 in 250,000 people around the world.

How Do You Get It?

  • While there are more than 20 genes associated with BBS, the underlying cause regardless of gene is malfunction of primary cilia, a key component of cellular communication. BBS is thus categorized as a ciliopathy, or a disease of the cilia.​
  • The biochemical mechanism that leads to this syndrome is still not fully understood.​

What Are The Symptoms?

  • BBS affects almost every organ system, and its diagnosis is based on different features of BBS such as:
    • Impaired vision​
    • Obesity​
    • Problems affecting urinary and genital organ function​
    • Chronic kidney disease​
    • Extra fingers and toes
      • Other malformations may also occur (webbing, shortness, or curving)​
    • Problems with language, thinking, judgment and memory
    • Developmental delays​
    • Endocrine disorders that may affect growth and development, metabolism, sexual function, reproduction and mood
    • Behavioral problems ​
    • Neurological problems ​
    • Hypertension (high blood pressure)​​
    • Speech disorders ​
    • Dental anomalies (small teeth, small lower jaw, short teeth) ​
    • Lack of a sense of smell (anosmia) ​
    • ​Short stature relative to parents’ height
    • Thyroid problems
    • Flat, wide feet

How Is It Treated?

  • There are no treatments for all of the characteristics associated with Bardet-Biedl syndrome.
  • As vision worsens, individuals will benefit from the use of low-vision aids and orientation as well as from mobility training. ​
  • Researchers have identified 12 genes that are linked to Bardet-Biedl syndrome, giving them clear targets for treatment development.​
  • Children with BBS benefit greatly from therapies like physical therapy, occupational therapy, speech therapy and vision services. Everyone with BBS benefits from exercise and careful attention to diet to limit weight gain.​
  • Early intervention can allow children to live the most normal life possible and manage symptoms, but there is no cure for the disease at this time.​
  • For Bardet-Biedl syndrome, renal failure is very common and is the most likely cause of death. Managing renal issues can improve life expectancy and quality of life.​
  • While some people with BBS lose most of their vision by their mid-teens, others have maintained enough vision to drive into their 30s. ​
  • While some people with BBS have significant learning disabilities and cognitive impairment, others do not and have IQ scores well above normal.
  • Most treatment research for the disease falls into three categories:
  • ​Stem cell therapy: Delivering new cells without the defective BBS gene that can multiply and replace defective cells within the body.
  • Gene therapy: Rather than replacing cells, replacing the defective gene inside of existing cells.
  • Suppressor therapy: Rather than changing DNA with new cells or in existing cells, overcoming the limitations of those cells by boosting their function through the inactivation of other genes or cellular pathways.​

Where Can I Learn More???

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