tag:blogger.com,1999:blog-1812431336777691886.post7254527748303510302..comments2024-02-29T03:57:00.088-05:00Comments on The Mermaid's Tale: The (bad) luck of the draw; more evidenceAnne Buchananhttp://www.blogger.com/profile/09212151396672651221noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-1812431336777691886.post-56418878703738473292017-05-09T06:15:32.096-04:002017-05-09T06:15:32.096-04:00There are people who argue that genetic variation ...There are people who argue that genetic variation is not the main cause of cancers. The journal BioEssays has articles by Adam Wilkins, and by Carlos Sonnenschein and Ana Soto, arguing for other explanations. Search on these subjects if you're interested.Ken Weisshttps://www.blogger.com/profile/02049713123559138421noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-80150584787912852772017-05-08T04:31:08.852-04:002017-05-08T04:31:08.852-04:00Assuming the vast majority of biological research ...Assuming the vast majority of biological research on cancer has been genetic, I wonder about a dysbalance of evidence: we might not know nearly enough about "errors" in cytoplasmic inheritance along cell lines to have a good sense of the relative importance of genetic vs. non-genetic cellular causes of cancer. What is your judgement on that? Alexhttps://www.blogger.com/profile/10489484831775772226noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-46497206782025412382017-04-05T09:30:23.517-04:002017-04-05T09:30:23.517-04:00If cosmic rays were mutagenic (I think that any th...If cosmic rays were mutagenic (I think that any that reach the surface of the earth aren't, but I'm not sure), then they are external to our bodies but in any epidemiological sense the effect on us would effectively be inherent. It is basically a semantic issue. The idea that DNA replication were perfect just a priori seems implausible, however. There are mutation detection and repair genes, showing that mutation is not due to human cultural exposures in particular, again, not the kinds of things epidemiologists are interesting.<br /><br />I think epigenomics in this context could be more exposure-dependent and more environmentally induced in some meaningful sense, but to argue that that is very different from mutation would at this time be risky. I think some epigenomic changes do seem to be due to exposures such as diet, at least in some dose-dependent, and hence epidemiologically relevant way. Ken Weisshttps://www.blogger.com/profile/02049713123559138421noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-63467102866763712972017-04-05T07:50:20.656-04:002017-04-05T07:50:20.656-04:00Thanks for that Ken. The key passage for me in the...Thanks for that Ken. The key passage for me in the paper is:<br /><br />"It is, of course, possible that virtually all<br />mutations in all cancers are due to environmental<br />factors, most of which have simply not<br />yet been discovered. However, such a possibility<br />seems inconsistent with the exhaustively documented<br />fact that about three mutations occur<br />every time a normal cell divides and that normal<br />stem cells often divide throughout life."<br /><br />There is obviously a lot of work and perhaps promise in latest epigenome-wide association studies. We shall see...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-8846271824768634792017-04-04T09:03:06.613-04:002017-04-04T09:03:06.613-04:00Epigenetics is only one of many ways cell behavior...Epigenetics is only one of many ways cell behavior can be changed (there is also RNA editing, RNA interference, noncoding RNAs and their various (largely unknown) functions. If an environmental factor is responsible for epigenetic changes (since this depends on DNA binding sites, regular mutation may be involved in epigenetic change), then it would be 'carcinogenic'. But if it is essentially random or weak etc., or for some reason its effects don't persist across cell division, and so forth, then for any practical purposes it is no different from random error in DNA replication. This would be in a grey area of causation, perhaps, but if it is not a systematic, statistically detectable factor, it is not something environmental epidemiologists could identify or do anything about. So it is essentially, and practically, an inherent aspect of DNA replication or behavior.<br /><br />The idea--I would say 'fact'--that DNA replication is chemically not a perfect process could imply the need for some external causal factor rather than pure randomness--whatever that would mean. But for any practical purpose (if not jealousy among scientific interest groups) replication is susceptible to error and that can be viewed as intrinsic rather than due to avoidable exposures. At that level the idea of external cause becomes essentially philosophical rather than scientific.Ken Weisshttps://www.blogger.com/profile/02049713123559138421noreply@blogger.comtag:blogger.com,1999:blog-1812431336777691886.post-50455832915099948432017-04-04T07:39:19.682-04:002017-04-04T07:39:19.682-04:00I see you haven't used the term epigenetics in...I see you haven't used the term epigenetics in discussing the paper - is this deliberate or not relevant? Anonymousnoreply@blogger.com