Multiple Sclerosis Risk Passed Equally By Both Parents?
Posted September 17, 2007 by Dr. T.R. Morris
Many genetic diseases have gendered predispositions. Multiple Sclerosis (MS) is one of these sex-linked diseases where women are affected about twice as often as men. The “Carter effect” dictates that in these diseases one can expect that offspring of the less effected gender (males in the case of MS) might be more likely to develop MS than children of the more affected gender (females) due to an expected loading of genetic risk factors in the physiologically resistant gender.
Last year, Neurology published a Mayo Clinic, National MS Society and NIH funded study which “proved” that the Carter effect is demonstrated in MS. The Study’s conclusion states: “The authors have demonstrated the Carter effect in multiple sclerosis (MS). These observations may be explained by greater genetic loading in men that leads to relative excess paternal vs maternal transmission.” Ah certainty. Feels good, doesn’t it?
Well, not so fast. According to a Canadian-based study also published in Neurology this summer, there is “no evidence for the Carter effect” in MS.
This is an example of how new the field of personalized medicine is, and serves as a reminder to keep our beliefs flexible while we continue to refine our understanding of the causes of diseases like MS.
Genetics Determine Effectiveness of Smoking Cessation Drugs
Posted September 17, 2007 by Dr. T.R. Morris
Smoking is considered one of the hardest addictions to break. Ever wonder why some people have an easier time kicking the habit than others? One answer comes from research in a new field of medical research called pharmacogenomics from the National Institute on Drug Abuse (NIDA). Read press release here.
This research indicates that people who have a genetic variant of the CYP2B6 gene (which codes for one of the enzymes that metabolize bupropion in the human body) were less likely than those without it to have resumed smoking six months after treatment with bupropion (Zyban). How prevalent is this variant? The good news for smokers is that it is present in 45% of Americans of European descent, 50% of African Americans and 25% of Asian Americans.
Once genetic testing is available for this variant, health care providers may have a better idea of who will respond better to the bupropion and, perhaps more importantly, who will respond best at particular doses.
This is one example of the growing field of pharmacogenetics—which many expect to usher in a new era of medicine where treatments are personalized based on individual genetic profiles. For more information on pharmacogenetics check out the National Center for Biotechnology Information’s Science Primer.
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