By Maayan Jaffe/JNS.org
Imagine that your child is born seemingly normal, but by age 1 or 2 has mental and physical disabilities. By 3, the child has epilepsy and is virtually vegetative.
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 Dr. Ohad Birk, head of the Genetics Institute at Soroka Medical Center in the southern Israeli city of Be’er Sheva and The Morris Kahn Lab of Human Genetics at Ben-Gurion University of the Negev (BGU), that number may soon be reduced.
On March 8, just four years after Birk’s discovery of genetic mutations in Iraqi and Moroccan Jews that lead to PCCA, he announced that his lab has unfolded a different genetic mutation that leads to another similar disease in Moroccan Jews, a disease he is calling PCCA2.
A paper on the subject is being published by the British Medical Journal publishing group and should be available to the general public within half a year.
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 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,” explained Birk. Eating items rich in selenium has no impact on affected children.
“These children have the same disease but from a different cause,” said 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 Birk’s lab, either in utero by chorionic villus sampling, or by pre-implantation in-vitro testing.
Birk, who said he hopes a similar blood test for PCCA2 will be available to Moroccan Jews within the year, began researching the gene mutations that led to the discovery of PCCA when several families …read more