A very informative commentary from Wendy Goldberg:
Ashkenazi Jews are a population with a large number of genetic mutations which have concentrated over centuries of inbreeding. There is genetic testing available based on family history of breast and other cancers to identify the markers BRCA 1 and 2, as well as to test survivors of cancer to determine if someone carries the genes that increase the risk of repeat diagnoses in various organs.
Pancreatic cancer is also associated with many genetic mutations.
Cancer is not the only genetic disease which is more common in Jews than the general population. Some of the genes can cause more than one disease. The GBA1 variation that causes Gaucher’s disease when both genes are affected can also cause Parkinson’s disease when only one gene is affected. The penetrance is only 5% for Parkinson’s disease. Of note, frequent vigorous exercise has been shown to reduce the risk for Parkinson’s.
Cancer is a complex disease. Germline mutations are different than somatic mutations (which occur in cells of the body due to environmental insult but are not heritable). Many cancers have multiple somatic mutations. The germline mutations may interfere with the body’s ability to detect and/or remove cancers caused by somatic mutations.