Скачать или смотреть The Founder Effect and Ashkenazi Jews

Frankie Foltz, Biology 112 UnEssay Assignment

Script/Outline:
If you’re one of the 26 million people who have taken an at-home ancestry test you may have noticed something weird—you’re part Ashkenazi Jew! Wait, what? You’re not Jewish. Also, how can you tell someone’s religion from their DNA?

That’s the catch—you can’t! The reason instead that Ashkenazi Jew shows up on your heritage report is that Ashkenazi Jew is actually a distinct genetic population, regardless of religion.

So how did this happen? A Founder Effect! A Founder Effect is when a small group of a larger population only procreates with each other, thereby reducing the size of the gene pool. With this comes a sort-of bottleneck in variability, making the new population distinct from the old one.

Founder effects usually happen due to geographic isolation, but In the case of the AJ population, the first founder event was due to cultural (mostly) isolation.

Now, a bit of a history lesson: Since the origins of the religion, the Jewish people have mingled with the rest of society, but they have mostly married and had kids with people within their own Jewish community. The bigger, more potent founder effect happened at the Diaspora—when the Temple of Solomon was destroyed around AD 70 by the Romans, the Jews fled from their home in Jerusalem to different parts of the Middle East (who became the Safardic) or to Eastern European (who became the Ashkenazi).

So back to the reproductive isolation: From the beginnings of the religion, the Jewish people have formed a tight-knit who This reinforced the fact that the AJs only married and had kids with themselves. Which was all well and dandy, until a few mutations arose.

See, since the gene pool had a limited size, when mutations arise, there’s a higher likelihood of them being passed on to the next generation. In some cases, this can be harmful and cause inherited diseases.

For the most part, AJ diseases are grouped into two categories: Lipid Storage Disorders such as Tay Sach’s disease, Gaucher’s Disease, and Nieman Pick disease; and Non-lipid Storage Disorders such as the BRCA1 and BRCA2 mutations that increase chance of getting breast and ovarian cancer, idiopathic torsion dystonia, familial dysautonomia, and others. To illustrate the the impact of the AJ Founder effect here, we’ll take one of the LSD’s: Gaucher disease occurs once about every 40,000 births in the general population, but in the AJ population, it occurs at a rate of once in every 450 births. That’s an 89% increase!

These diseases vary in the effects they have on people. In some cases, people go years without noticing they have one of these conditions, but in others like Tay Sach’s, the disease can drastically lower quality of life and even be fatal. For this reason, many healthcare practitioners recommend getting tested for carrying these genes before having children. In other cases, knowing that the cause of symptoms of illness is genetic can alter the recommended treatment, such as trying enzyme replacement treatment or generalized gene therapy.

In fact an area where a ton of research is currently being conducted is on patients diagnosed with a BRCA1 or BRCA2 mutation—if these patients are at up to 60% of an increased risk of breast cancer, how often should they go in for mammograms? Does the radiation from mammograms pose a higher risk of negatively impacting these individuals? Are there risk-free blood tests we can do to monitor these risks instead?

Sources:
1. Bray, S. M., Mulle, J. G., Dodd, A. F., Pulver, A. E., Wooding, S., & Warren, S. T. (2010). Signatures of founder effects, admixture, and selection in the Ashkenazi Jewish population. Proceedings of the National Academy of Sciences, 107(37), 16222-16227.
2. Ferla, R., Calo, V., Cascio, S., Rinaldi, G., Badalamenti, G., Carreca, I., ... & Russo, A. (2007). Founder mutations in BRCA1 and BRCA2 genes. Annals of Oncology, 18(suppl_6), vi93-vi98.
3. Kaplan, K. (2014, September 9). DNA ties Ashkenazi Jews to group of just 330 people from Middle Ages. In The Los Angeles Times.
3. Labuda, D., TKIEWICZ, E. Z., & LABUDA, G. (1997). The genetic clock and the age of the founder effect in growing populations: a lesson from French Canadians and Ashkenazim. The American Journal of Human Genetics, 61(3), 768-771. Retrieved from https://www.cell.com/ajhg/pdf/S0002-9... .
4. More than 26 million people have taken an at-home ancestry test. A Regalado MIT 693 Technology Review, 2019.
5. Slatkin, M. (2004). A population-genetic test of founder effects and implications for Ashkenazi Jewish diseases. The American Journal of Human Genetics, 75(2), 282-293.
5. Struewing, J. P., Abeliovich, D., Peretz, T., Avishai, N., Kaback, M. M., Collins, F. S., & Brody, L. C. (1995). The carrier frequency of the BRCA1 185delAG mutation is approximately 1 percent in Ashkenazi Jewish individuals. Nature genetics, 11(2), 198. Retrieved from https://www.nature.com/articles/ng109....