Researchers at Ben-Gurion University have solved the riddle of a severe genetic disease that affects Jews of Moroccan ancestry. PCCA 2 (Progressive Cerebello-Cerebral Atrophy Type 2) is a hereditary disease that one out of every 37 Moroccan Jews carries and can cause severe brain atrophy, mental retardation and epilepsy.
A research team led by Prof. Ohad Birk, head of the Genetics Institute at the Soroka Medical Center and BGU’s Morris Kahn Lab, found that the disease is caused by two mutations in a gene that results in defective circulation of vacuoles (endosomes) within patients’ cells and leads to detrimental excessive storage of “junk” within the cells.
PCCA 2 potentially affects one million people in Israel – Jews of Moroccan ancestry, who make up 15% of the population – as well as the nearly 100,000 Moroccan Jews also live in the United States, largely in New York City, Washington D.C., Boston, and Florida.
“There was an idea that Ashkenazi [of European descent] Jews have more disease than others, but when one begins looking at Sephardic Jewish diseases, they are there,” said Birk. “They have just not been sorted out. Because they have not been sorted out, there was no carrier testing, no prevention programs or anything. I have shifted part of my lab into Jewish non-Ashkenazi-or Sephardic Jewish-diseases.”
A study describing the research was published in the latest online edition of the Journal of Medical Genetics. The study was conducted by Miora Feinstein in Prof. Birk’s lab as part of her doctoral thesis and funded by the Israel Science Foundation and the Legacy Heritage Fund.
Children who contract PCCA 2 seem fine at birth and develop well until about six months of age. But deterioration begins soon after, with brain atrophy, severe retardation and epilepsy setting in by age one.
PCCA 2 is a recessive disease, which means that babies have a 25 percent risk of becoming victims of the disease in each pregnancy – making it the most common genetic disease affecting Jews of Moroccan Jewish backgrounds. The Health Ministry said, in light of the research, it would in the coming months begin offering PCCA 2 tests as part of its routine screening for pregnant women.
Birk has also been responsible for discovering the genetic formulas for a number of other diseases. In 2010, a research team led by Birk discovered the gene mutation that causes PCCA, a similar disease that affects one out of forty Moroccan and Iraqi Jews. A PCCA screening test has been available for pregnant women since 2010. Research teams led by Birk have led to the discovery of more than 20 genetic diseases common in Arabs and in Sephardic Jews.
He also made history in 2012, when he was invited to participate in the BBC’s prestigious “Doha Debates” discussion program – one of the few Israelis to appear on the program that is seen across the Arab world. Birk discussed the question of discouraging marriage between close family members, a practice common in many parts of the Arab world, and one that many geneticists believe leads to an increase in birth defects.
Birk was invited to the program because of his work on genetic diseases in the Bedouin community. Birk’s research has led to the discovery of some 20 genetic diseases in the Bedouin community due to consanguinity, while running a program that has reduced the infant mortality rate in the Negev Bedouin community by 25% over the past five years.
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