Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!cmcl2!rocky8!cucard!aecom!werner From: werner@aecom.YU.EDU (Craig Werner) Newsgroups: sci.bio Subject: Re: The Ubiquity of Tay-Sachs: a shocking but elegant theory Summary: Multiple origins of Tay-Sachs Message-ID: <2103@aecom.YU.EDU> Date: 13 Feb 89 11:35:26 GMT References: <10276@ut-emx.uucp> <789@bimacs.BITNET> Organization: Albert Einstein Coll. of Med., NY Lines: 31 In article <789@bimacs.BITNET>, kanov@bimacs.BITNET (Mechael Kanovsky) writes: > > In article eric@snark.uu.net (Eric S. Raymond) writes: > >In <10276@ut-emx.UUCP> ethan@ut-emx.UUCP (Ethan Tecumseh Vishniac) writes: > >>Not being a geneticist, I have frequently wondered, but never looked into, > >>the question of why an infrequent mutation like Tay-Sachs, which has such > >>a devastating effect on those unfortunates who are homozygous for it, has > >>such a relatively *high* incidence among Ashkenzaic Jewry (I believe that > >>1/30 individuals is heterozygous). > > > The plot thickens even more when you consider that the Tay-Sachs mutation actually arose at least four separate times independently (that is, there are four distinct gene patterns, all distinguishable from one another by standard molecular genetic techniques that cause a defect in the same enzyme, and thus create the Tay-Sachs trait. This is quite a large number when you consider that Sickle Cell seems only to have arisen twice. Now some persons on the net have suggested that the selecting force for the mutation was the Black Plague, Yersinia pestis. That's one I hadn't heard before, but I certainly can't refute it. However, a theory which does seem to have some support, although one that is by no means proven, is that the selection was rather the Great White Plague, namely that disease endemic to cities until the 20th century, Tuberculosis. -- Craig Werner (future MD/PhD, 4 years down, 3 to go) werner@aecom.YU.EDU -- Albert Einstein College of Medicine (1935-14E Eastchester Rd., Bronx NY 10461, 212-931-2517) "Until it's on daytime television, it's impossible, and that's the final word."