Joubert Syndrome

Joubert syndrome is a rare genetic disorder where the brain develops abnormally, causing an absent or underdeveloped cerebellar vermis (i.e., part of the brain that controls balance and coordination) and brainstem. The condition is typically apparent in infancy and more common in those of Ashkenazi Jewish, French-Canadian, and Hutterite ethnicities. 

Joubert syndrome is typically inherited but can be sporadic. When inherited, there is a wide variety of genes implicated, including CPLANE1, TMEM67, AHI1, and CC2D2A. Joubert syndrome typically has an autosomal recessive inheritance pattern, meaning to have the condition, an individual must inherit two altered genes: one from each parent. There is a more rare form of Joubert syndrome that is inherited in an X-linked recessive pattern, which is when the altered gene is located on the X chromosome and mostly affects those assigned male at birth.

The signs and symptoms of Joubert syndrome are often apparent during infancy and can vary widely but primarily include developmental or intellectual delays and low muscle tone (i.e., hypotonia). Other manifestations can include lack of muscle control (i.e., ataxia), abnormal breathing patterns (i.e., hyperpnea), sleep apnea, abnormal tongue and eye movement (i.e., nystagmus), and seizures. Other eye abnormalities can include widely spaced eyes, crossed eyes (i.e. strabismus), and visual impairment. Individuals may also present with anatomical abnormalities, such as tongue abnormalities, cleft lip or palate, and polydactyly (i.e., more than five fingers or toes on a single hand or foot).

Treatment for Joubert syndrome is usually supportive and aimed at addressing the affected child’s specific symptoms. 

A child with intellectual or developmental delays may undergo physical therapy, speech therapy, and occupational therapy as well as educational support programs to provide help meeting their goals. If there are any respiratory or breathing issues, they may require supplemental oxygen, mechanical ventilation, or a tracheostomy. With eye abnormalities, surgery or corrective lenses may be required. And lastly, with any liver or kidney abnormalities, dialysis or kidney transplantation may be needed. While anatomical issues (e.g., polydactyly) can be treated surgically, symptoms (e.g., eizures) may be treated with medication.

Individuals with Joubert syndrome benefit from care through an interdisciplinary team, including neurologists, ophthalmologists, nephrologists, and geneticists as well as regular follow-up appointments to monitor the condition.