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The Wandering Gene and The Indian Princess
Race, Religion and DNA
BRCA1 and BRCA1 stands for breast cancer. It is not a breast cancer gene, it is a tumor-suppressing gene. BRCA1 is a rare mutation which disables function. A very long gene, thousands of letters long, so with lots of places for things to go wrong. At position 185 there's a mutation which deletes Guanine and Adenine, so it's called 185delAG. A very old mutation - entered Jewish population about the time of the Babylonian captivity. Can work that out because groups separated since then (specifically the Iraqi Jews and the ones who went back to Palestine, then on to Europe and became the Ashkenazi Jews) have the same spelling around the 185delAG mutation.
The mutation only occurred once (otherwise the letters would differ). So every carrier is a direct descendant of a Judean who lived 2500 years ago.
When the mutation shows up in another racial group, it's a sign that a Jew or descendant of a Jew has married into the population. For example there is a high incidence in hispanics in New Mexico. They have inherited it from Spanish conquistadors who came and then left, in the C17th. They in turn inherited it from Jews who lived in Spain during the first millenium AD.
Ashkenazi Jews went through a bottleneck as a result of persecution after the Crusades. They wound up in eastern Central Europe, with numbers down to about twenty thousand. By 1900 it was up to ten million. But harmful mutations emerged from the bottlenecks - all told the Jews of Central and eastern Europe are host to forty or more genetic disorders.
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