Joubert syndrome, AHI1-related

What is Joubert Syndrome, AHI1-related?

Joubert syndrome, AHI1-related, also known as Joubert syndrome type 3, is an inherited condition that causes brain structure abnormalities. There are several genes associated with Joubert syndrome. Joubert syndrome, AHI1-related is caused by harmful genetic changes (variants) in the AHI1 gene. Individuals with Joubert syndrome, AHI1-related have problems with the structure and function of their cilia, which are finger-like projections on cells that are important for chemical signaling pathways. These malfunctioning cilia lead to physical abnormalities during development.

Individuals with Joubert syndrome, AHI1-related have low muscle tone (hypotonia), developmental delay, and a distinctive brain malformation called a "molar tooth sign" that can be seen on brain imaging (MRI). Brain imaging may also show increased folding of brain tissue in these individuals (polymicrogyria). Joubert syndrome, AHI1-related is also characterized by specific eye abnormalities such as the inability to control eye movements correctly and missing eye tissue (ocular coloboma). Approximately 80% of individuals with Joubert syndrome, AHI1-related have some disease of the retina (retinal dystrophy). Individuals with Joubert syndrome, AHI1-related often have abnormal breathing patterns and difficulty coordinating their muscle movement (ataxia), though these symptoms tend to improve over time. Some individuals with Joubert syndrome, AHI1-related have cystic kidney disease, which can progress to end-stage renal disease.

Children with Joubert syndrome, AHI1-related typically have mild to severe intellectual disability, but there are reports of individuals with average intellect. Many children also have speech and motor skills delays and exhibit behavioral issues.

How common is Joubert Syndrome, AHI1-related?

Over thirty genes are associated with Joubert syndrome. The exact incidence of Joubert syndrome has not been determined but is estimated to be about 1 in 80,000 to 1 in 100,000 births. Approximately 7-10% of Joubert syndrome is caused by harmful genetic changes in AHI1.

How is Joubert Syndrome, AHI1-related treated?

There is no cure for Joubert syndrome, AHI1-related. Treatment for the condition is directed at managing an individual’s specific symptoms. Children with Joubert syndrome, AHI1-related should be followed by a team of specialists and monitored for eye and kidney problems. Dialysis and/or kidney transplantation may be necessary in cases of end-stage renal disease. Corrective eye interventions can be used as needed. Infants and children with breathing problems should be monitored for apnea. Common interventions for developmental delays include evaluation and care by physical therapy, speech pathology, and occupational therapy.

What is the prognosis for an individual with Joubert Syndrome, AHI1-related?

The prognosis for individuals with Joubert syndrome, AHI1-related can vary widely depending on the severity of symptoms and associated complications. Some have more severe intellectual disability, progressive retinal dystrophy, renal disease, and severe ataxia, while others have close to average intellect, mild ataxia, less severe retinal dystrophy, and no kidney involvement. Lifespan may be reduced in those with kidney failure or severe breathing abnormalities. For those with kidney involvement, end-stage renal disease typically occurs by the second decade of life.