A new gene for a genetic disease has been identified among Jews from North Africa and Iraq

קA research team headed by Prof. Ohad Birak, Director of the Genetics Institute at the Soroka Medical Center and the National Institute of Biotechnology in the Negev at Ben-Gurion University identified the gene whose defect causes cases of mental retardation accompanied by convulsions among Jews of North African and Iraqi origin.

As part of the study, two different mutations were identified in the same gene - one among the Iraqi population and the other among Moroccan Jews. The mutations are quite common: one in every 40 people among these populations is a carrier of the mutation. In light of the severity of the disease and its high prevalence, a blood test to identify these mutations is expected in the near future to become a pre-pregnancy genetic screening test among Jews of the relevant origin. The disease is recessive, so only if both partners carry the mutation is there a fear of the disease among their children. Hence, performing the test will only be recommended in couples where both partners are Jews of North Africa and/or Iraq.

From a scientific point of view, the interest in the discovery is great: according to the genetic code, 20 amino acids are the building blocks for creating all the proteins in the human body. In recent years it turned out that there is another amino acid (selenocysteine), which contains the element selenium. The disease results from a defect in the production of this amino acid.

Prof. Ohad Birak: "The coding for the 21st amino acid is different from the usual - and is done by a codon whose usual function is to create a stop in the formation of the protein chain. Only 25 proteins in the human body have a special mechanism that causes this codon to place selenocysteine ​​in the protein chain, instead of stopping the production of the chain. The disease characterized in this study is the first disease in which a defect in the production of the 21st amino acid is described. This finding is a breakthrough in understanding the role of this amino acid and the proteins that contain it in the human body. Since it is a progressive disease, in which the brain tissue is normal at birth and degenerates during the first years of life, it is possible that understanding the mechanism of the disease will enable innovative therapeutic approaches in the future that will stop the progression of the degenerative disease."

The research was carried out as part of Orli Agami's doctoral thesis from Prof. Birak's laboratory and is published this week in the prestigious American Journal of Human Genetics. Research partners are Dr. Boruria Ben Ze'ev, Prof. Tali Sagi and Dr. Dorit Lev. The research was funded by the Morris Kahn Family Foundation, the Morsha Foundation and the Israel Science Foundation. It should be noted that Prof. Birak's research group has so far deciphered the mechanism of 15 diseases in humans.