People with Joubert syndrome 2 (JBTS2) face challenges such as delayed development, difficulty moving their muscles, involuntary eye movements, and trouble controlling their gaze. They might also have problems with intellectual abilities.
From birth, these individuals have weak muscles, making it hard for them to eat and causing breathing difficulties. Their eyes move quickly and uncontrollably, sometimes rotating inward. Some may even have extra fingers or toes. Kidney problems, which can lead to kidney failure during teenage years, are also possible. Children with JBTS2 experience delayed mental and physical growth. While some may have mild intellectual disability and muscle control issues, others could face severe challenges. In the early years, their eye problems often get better, allowing for normal vision. A small number might have a shorter life expectancy due to kidney or liver problems and breathing difficulties. The impact of JBTS2 on each person is unique, and their experiences can vary widely.
JBTS2 is caused by pathogenic (disease-causing) variants in the TMEM216 gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 92 chance to be a carrier.
Other names for this condition are agenesis of cerebellar vermis, cerebello-oculo-renal syndrome, familial aplasia of the vermis, and Joubert-Bolthauser syndrome.