Razib Khan One-stop-shopping for all of my content

August 5, 2011

The social goods of individual actions

Over at Genetic Future Dr. Daniel MacArthur has a measured response to a Nature commentary by David Goldstein, Growth of genome screening needs debate. As Dr. MacArthur notes an excessive portion of Goldstein’s piece is taken up with inferences derived from assuming that the model of rare variants causing most diseases is correct, when that is an issue currently in scientific contention (and this is a debate where Goldstein is a primary player on one side). But the last two paragraphs of the piece is where the real action is, no matter the details of genetic architecture of diseases:

One potential problem with this is that numerous genetic risk factors will have diverse and unexpected effects — sometimes causing disease, sometimes being harmless and sometimes perhaps being associated with behaviours or characteristics that society deems positive. Even for simpler Mendelian diseases, up to 30% of the mutations originally termed pathogenic have turned out to be apparently harmless…Wholesale elimination of variants associated with disease could end up influencing unexpected traits — increasing the vulnerability of populations to infectious diseases, for instance, or depleting people’s creativity.

There are no clear-cut answers to the questions of what should be screened ...

February 8, 2011

Jacob’s Legacy: A Genetic View of Jewish History

Link to review: Jacob’s Legacy: A Genetic View of Jewish History.

January 19, 2011

The rise of genetic architecture

In science, like most things, one prefers simple over complex whenever possible. You keep adding variables until the explanatory juice starts hitting diminishing marginal returns. So cystic fibrosis is due to a mutation at one gene, and the disease expresses recessively at that locus. The reality is that one mutation accounts for ~65-70% of cystic fibrosis cases around the world, and there are nearly ~1,400 known mutations on the CFTR locus. How about skin color? Mutations on a dozen genes can probably explain ~90% of the variance in the trait value across the world between populations. In fact, one single mutation on one base pair can explain ~30-40% of the trait value difference between Europeans and Africans. This is a more complex story that cystic fibrosis; you have not just many mutations, but many mutations across many genes. But, the number of genes and mutations are manageable. You can keep track of most of them in your head (e.g., I can tell you that SLC24A5, SLC45A2, KITLG, and HERC2, can explain most of the trait value difference between Africans and Europeans without looking it up).

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