Joubert Syndrome, TMEM216 Related

Gene : TMEM216

What is Joubert syndrome?

Joubert syndrome (JBTS) is an inherited disorder that affects multiple systems in the body. One of the key features of JBTS is an abnormality in the brain called molar tooth sign, which can be seen on brain imaging studies such as magnetic resonance imaging (MRI). Other symptoms of JBTS may include weak muscle tone in infancy with later development into uncoordinated muscle control, abnormal breathing in infancy, eye abnormalities, kidney disease, liver disease, skeletal abnormalities, hormone problems, and characteristic facial features. Most affected children have developmental delay and intellectual disability, which can range from mild to severe. The life expectancy of individuals with JBTS may be affected because of the specific manifestations of the disorder. There is no cure for JBTS but medical surveillance and care may help to improve some symptoms and overall condition of life. One of the causes of JBTS is pathogenic variants in the TMEM216 gene.

How is TMEM216-related JBTS inherited?

TMEM216 -related JBTS is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for JBTS. However, the risk to have a child affected with JBTS is increased. Testing of reproductive partners is recommended for carriers of JBTS.

How common is JBTS?

Currently JBTS is estimated to occur in 1 in 80,000 to 100,000 newborns, but this may represent an underestimate. The TMEM216 related JBTS appears to be more common in the Ashkenazi Jewish population.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems






Carrier Rates
Detection Rate
Carrier Frequency
Ashkenazi Jewish > 99% 1 in 4
General Population > 99% 1 in 869

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