Researchers from Ben-Gurion University in Be’er Sheva have identified the genetic mutation behind a hereditary disease that causes epilepsy and severe developmental delays among Moroccan Jews.
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The disease, which the researchers are calling Progressive cerebello-cerebral Atrophy, type 2, is caused by mutations in the VPS53 gene. The research was published online this week in the Journal of Medical Genetics.
The researchers found that one in 37 Moroccan Jews carries one of the two mutations of the gene. Affected children seem normal at birth but at about six months brain atrophy begins and they begin deteriorating. By their first birthday they are severely mentally retarded, with enhanced muscle tone and epilepsy.
The research team, led by Dr. Ohad S. Birk, head of the Genetics Institute at Soroka Medical Center and the director of the Morris Kahn Laboratory of Human Genetics at the National Institute for Biotechnology in the Negev, showed that the mutations in the gene cause defective circulation of vacuoles (endosomes) within patents’ cells, leading to detrimental excessive storage of “junk” within the cells.
PCCA 2 is a recessive disease: If both parents are carriers of the VPS53 mutation, there is a 25-percent risk of the disease with each pregnancy. In light of the high carrier rate for the disorder, screening for the disease will likely be added to the routine genetic testing offered to couples of Moroccan Jewish heritage.
The study, funded by the Israel Science Foundation, the Legacy Heritage Fund and Teva Pharmaceutical Industries, was conducted as part of the doctoral work of Miora Feinstein in the laboratory of Dr. Birk, with the participation of Dr. Hagit Flusser, Dr. Bruria Ben-Zeev, Prof. Tali Sagi, Dr. Dorit Lev, Dr. Orli Agami and other students from the research laboratory.
In 2010, Dr. Birk’s research group discovered the gene for PCCA, a similar disease that is common in Jews of Moroccan and Iraqi ancestry. (One out of every 40 people in both groups is a carrier). The mechanism of PCCA is completely different from that of PCCA 2.
Because of the frequency of the disease among the Moroccan and Iraqi Jewish communities, starting in 2011 the Health Ministry included tests for PCCA as free tests for these populations.
PCCA and PCCA 2, two of the most severe and prevalent genetic diseases among Moroccan Jews, were never described in the past. The decoding of their genetic basis and their biochemical mechanism makes their prevention possible.
Carrier testing and prenatal diagnosis will enable eradication of this severe disease, as has previously been done for other common genetic disease in Jews, such as Tay Sachs.