Genetics: Joubert Syndrome gene discovered

A genetic mutation causing Ashkenazi Jewish children to be born with Joubert Syndrome - a neurological genetic disease - was discovered by Hadassah University Medical Center in Jerusalem and Dor Yeshorim (Committee for the Prevention of Jewish Genetic Diseases) researchers.

The finding will be published in the American Journal of Human Genetics (January 2010 edition), and the announcement appeared in the Southern California Hadassah Blog.

Hadassah's Department of Genetics and Metabolic Diseases has, in the past two years, discovered 13 genes - including this newest one - whose mutations may cause genetic diseases in children.

Joubert Syndrome affects the cerebellum, which is responsible for controlling balance and coordination of skeletal muscles. Infants born with this condition demonstrate decreased muscle tone, difficulty in swallowing, jerky eye movements and an inability to coordinate voluntary muscle movements. As the children grow, they may suffer from mental retardation and develop kidney failure.

According to the article, Dor Yeshorim was concerned with an increasing number of children born with the syndrome in recent years, and asked Hadassah to investigate.

Analysis of the children's DNA showed each had an identical 14-gene segment. Research identified the one with the mutation that causes the syndrome.

Based on these initial findings, researchers examined the DNA of 3,000 healthy Ashkenazi Jews and discovered that one out of 92 Ashkenazi Jews carried the mutation. This means that one of every 8,000 Ashkenazi Jewish couples may have a child with Joubert Syndrome.

NOTE: Tracing the Tribe wonders about the genetic genealogy matches of the test group. In the past, several studies have initially pointed to "Ashkenazi" conditions, later adjusted to simply "Jewish" genetic conditions, when the same conditions were found among Sephardim. A recent example (2006) was Yeshiva University's study on the discovery of an "Ashkenazi" Parkinson's gene. The definition was amended a few years later when the same gene was found among Sephardim. How many of these Joubert Syndrome test subjects may have a Sephardic oral history or other markers?

The Hadassah researchers included Dr. Simon Edwardson, Dr. Avraham Shaag, Dr. Shamir Zenvirt, and Prof. Orly El-Peleg, with the participation of Dor Yeshorim.

For more information on Hadassah's health and medicine activities, click here.