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Birk is prolific, having discovered and documented more than 50 mutations and applied his research to help people who are susceptible to them. The SLC38A8 mutation is the first one found to be widespread among Jews of Indian ancestry, with three other genetic diseases — the endocrine disorder ACTH deficiency, the blood clotting disorder factor XIII deficiency and Fanconi anemia — known to affect only one or two Indian-Jewish families.
In recent years, Birk’s team discovered genes that are linked to the two most common genetic diseases among Jews of Moroccan ancestry, who account for some 15% of Israel’s population and 100,000 people in the United States. Progressive cerebellocerebral atrophy (PCCA) and PCCA Type 2 are two fatal diseases with similar symptoms caused by different genetic mutations. Affected newborns appear to be developing normally until the age of six months, when their brains begin to atrophy. By age one, they suffer from severe mental retardation, and most die between the ages of 10 and 20. In March, Miora Feinstein, a doctoral student under Birk’s supervision, identified two recessive mutations in the VPS53 gene that are responsible for PCCA Type 2, and found that 1 in 37 Jews of Moroccan origin carries both mutations.
This came four years after Birk’s group discovered that mutations in the SEPSECS gene — carried in 1 in 40 Jews of Moroccan and Iraqi descent — were responsible for PCCA. Birk is confident that state-funded genetic testing, which has been available for SEPSECS mutations since 2011, and prenatal diagnosis will enable eradication of the disease in Israel.
In addition to making breakthroughs with Indian and Moroccan Jews, Birk is also one of the first to explore Ethiopian Jewry’s unique genetic legacy. “They are one of the only Jewish communities that made sure not to marry within the family,” Birk said. “Ethiopian Jews living in Ethiopia kept a registry and made sure before every marriage that eight generations back they were not related. They stuck to this very carefully, and only now that they are in Israel is this beginning to change.”
In the new country, Ethiopian Jews no longer defer to the registry. And so, just as other diseases such as the deadly PCCA and PCCA2 are being reined in, the story of genetic diseases in the Ethiopian community is just beginning. One family has already come forward with a new mutation — one Birk is already hard at work researching, though he’s not yet comfortable speaking publicly about the disorder it causes. He expects to publish findings in about half a year.