Revealing the Source of a Jewish Genetic Disease
Revealing the Source of a Jewish Genetic Disease
March 13, 2014
The Jewish Voice — Imagine that your child is born seemingly normal, but by age one or two he or she has mental and physical disabilities. By three, the child has epilepsy and is virtually vegetative.
Prof. Ohad Birk
This phenomenon, known as Progressive Cerebro-Cerebellar Atrophy (PCCA), affects dozens of Israeli families of Iraqi and Moroccan-Jewish descent.
But thanks to the team of reseachers led by Prof. Ohad Birk, head of the Genetics Institute at Soroka University Medical Center and The Morris Kahn Lab of Human Genetics at BGU, that number may soon be reduced.
On March 8, just four years after Prof. Birk’s discovery of genetic mutations in Iraqi and Moroccan Jews that lead to PCCA, he announced that his lab has identified a different genetic mutation that leads to another similar disease in Moroccan Jews, a disease he is calling PCCA2.
Research shows that PCCA2 is caused by mutations in the gene VPS53. Two different mutations in this gene were found in Moroccan Jews.
Miora Feinstein, a graduate student in Dr. Birk’s lab, showed that the VPS53 mutations cause defective circulation of vacuoles (endosomes) within patients’ cells, leading to detrimental excessive storage of “junk” within the cells.
PCCA2 is a recessive disease, meaning that if both parents are carriers of a VPS53 mutation, there is a 25 percent risk of the disease in each pregnancy.
The mutation causing the similar disease, PCCA (which was discovered in 2010 in Iraqi and Moroccan Jews), is in a different gene and acts through another molecular mechanism, prohibiting selenium from being utilized in the body.
The mineral selenium is needed by 25 different brain proteins, and without it there is atrophy of the brain, “leaving a gap between the brain and the skull that should not be there,” explains Dr. Birk. Eating items rich in selenium has no impact on affected children.
“These children have the same disease but from a different cause,” says Dr. Birk.
Now, PCCA and PCCA2 are the two most common genetic diseases in Jews of Moroccan descent. Deciphering the genetic and molecular mechanism of the diseases enables their prevention.
Not long after the 2010 report about PCCA was published, parents in Israel were able to be screened for carrier status by a simple blood test. Couples that were found to be carriers were offered free testing of their embryos for the disease at Prof. Birk’s lab, either in utero by chorionic villus sampling, or by pre-implantation in-vitro testing.
Prof. Birk hopes a similar blood test for PCCA2 will be available to Moroccan Jews within the year.
Read more of this article by Maayan Jaffe on the Jewish Voice website >>
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