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Genomics Is Not Magic, There Is No Magic

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MIT Technology Review has an article up, Do Your Family Members Have a Right to Your Genetic Code?, which is now part of the genomics-human-interest-piece genre you see regularly. Here you have the exemplar of this sort of narrative: what do you do when one twin gets a test and the other does not, and they disagree on how much they want to know? (obviously the twin being tested is a “I-want-to-know”) In this case though there is a twist: both of them are scientifically highly trained. And, it turns out that the twin who was worried/nervous about genetic results turned out to have ‘actionable’ results from the other twins’ decision.

There’s a major problem I have with this genre: genomics is not magic, genetics predates genomics by 100 years, and genetics predates DNA based molecular biology by 50 years. That means the basics of this dilemma have been present for over a century. Here are the conditions:

1) You have a condition
2) That condition is heritable
3) You have family members with varying degrees of relatedness to you

If it’s a highly penetrant variant, by which I mean that a very high proportion of individuals with the mutant allele will develop the condition, then the very fact of any individual being diagnosed has implications across the whole pedigree. Do you then keep it a family secret? Do you speak of it to friends? Do you avoid support groups based on the disease for reasons of genetic privacy?

Obviously sequencing an identical twin is a reductio ad absurdum. There’s very little uncertainty for highly penetrant alleles in this case. You know what the allele simply by inspecting the genome, even before diagnosis of any disease or condition (it may be a late in life disease). And, identical twins are almost perfect concordant in their genome. But qualitatively the same concerns have been present in some form for over a century.

Every disease you manifest and every trait you show on your face is a reflection on the genetics of your extended pedigree. Any information you divulge as a matter of course or happenstance then becomes a “bioethical dilemma.” The choices you make will smoke out values. For example, I weight the interests and privacy of the nuclear family far more than even the nearest circle of relations. I would without much thought sacrifice the diluted expectation of privacy (diluted because of diminished relatedness) for my extended kin (siblings, parents, cousins) if I needed information to help my children. In contrast, if I lived in a Hindu joint family my calculus might be different.

• Category: Science • Tags: Genetics 

4 Comments to "Genomics Is Not Magic, There Is No Magic"

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  1. Not quite on topic (and perhaps a bit pedantic), but I want to be sure of a piece of information I picked up along the way…

    My understanding is that even identical twins are not (completely?) identical, that there is (usually?) some very, very small percentage difference (perhaps on the order of 1%? not sure) between them and that this difference is usually related to the cause of the twinning. That is, that there was some incompatibility between genes in the original genome and the twinning-with-differences is a solution to this.*

    Is this correct? Can you point me to something that would clarify this for me?


    *In my mental storage system, I keep this in the same compartment with the fact that the X & Y chromosomes actually do exchange some genes during meiosis, genes near the telomeres.

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  2. there mutational differences that build up. so high coverage (very accurate) sequencing can distinguish ident twins. though it’s nowhere near 1%, unless you are sampling cancerous tissue or something highly mutable i assume.

    the thing you are talking about, i don’t know of.

  3. Mildly OT: is offering a $69 sale for its testing. Worth it, or should I tell my interested family members to stick with 23andMe?

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  4. if they have a lot of money 23andMe might be more convenient. but they probably won’t drop the price in the near future. so ancestry is best if u r interested in genealogy.

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