Doctors, Genes, Family Trees, Quora and Hemochromatosis

by Stephen Cobb on April 5, 2011

QUORA

Have you visited Quora yet? It’s a increasingly popular website that bills itself as “a continually improving collection of questions and answers created, edited, and organized by everyone who uses it.” On a recent visit to Quora I saw this question:

Q. What are reasons that I should not submit my DNA to a firm like 23andMe?

You can read the question and answers here. This question caught my eye because, as regular readers will know, I did submit my DNA to 23andMe. Personally, I could not think of any reason not to do so. Apparently, not everyone shares my attitude, which is fine, but one person provided an answer that was, IMHO, wide of the mark. Here is what I submitted to Quora in response to Person X:

Me: I see no reason not to submit your DNA to 23andMe. And I have to warn you that the following assertions are, in my experience, somewhere between naïve and dangerously wrong:

“First of all, your doctor is going to notice in your family history if said disease is wreaking havoc on your family tree.” – -Person X

Me: My wife’s family was decimated by hereditary hemochromatosis over a period of 40 years and scores of doctors failed to notice it. My wife presented classic hemochromatosis symptoms to at least a dozen doctors herself, over a period of 15 years, before one of them connected the dots.

Her case is not just an isolated example. A landmark CDC study showed that hemochromatosis sufferers had symptoms for an average of 9.5 years and saw more than 3 doctors before being correctly diagnosed.

“Secondly, many diseases with a clear genetic linkage present themselves early in life, often when patients are still quite young.” — Person X

Me: This is not entirely untrue, but it is terribly vague. For example, women often do not get the symptoms of hereditary hemochromatosis until menopause, at which point they can have suffered serious organ damage. Indeed, it is unusual for hereditary hemochromatosis to cause symptoms before adulthood.

“You’re probably not going to find a big nasty surprise buried in your genes. And even if you do find said nasty surprise, most doctors are not going to start treating you until your body actually starts showing symptoms.” — Person X

Me: There are two serious problems with this statement. First, knowing that you are a genetic carrier can help your doctor catch the symptoms sooner. For example, if you are homozygous for hemochromatosis then a simple blood iron test administered as part of a regular physical can detect elevated iron levels before they do long term damage. Since iron tests were dropped from standard blood panels in the US in 1996 [due to several cases of billing fraud by unenthical labs], many insurance companies won’t cover these tests without cause, and a positive gene test is a better cause than waiting for someone to be sick.

Secondly, there are numerous nasty surprises you can find in your genetic data. I count myself lucky that I am not a carrier of Alpha-1 Antitrypsin Deficiency, Bloom’s Syndrome, Canavan Disease, Cystic Fibrosis, Familial Dysautonomia, Factor XI Deficiency, Fanconi Anemia (FANCC-related), Familial Hypercholesterolemia Type B, Familial Mediterranean Fever, Gaucher Disease, Glycogen Storage Disease Type 1a, Hemochromatosis, Limb-girdle Muscular Dystrophy, Maple Syrup Urine Disease Type 1B, Mucolipidosis IV, Niemann-Pick Disease Type A, Connexin 26-Related Sensorineural Hearing Loss, Phenylketonuria, Rhizomelic Chondrodysplasia Punctata Type 1 (RCDP1), Sickle Cell Anemia, Tay-Sachs Disease, or Torsion Dystonia.

I am also thankful that, because of 23andMe and my own interest in my health, I know that I am not a carrier. Ignorance is seldom bliss. I don’t plan on fathering any children, but if I was a younger man I would want to know about my genetic carrier status before I did. A gene test that reveals you are a carrier of something like hemochromatosis or Gaucher could make a big difference to your decisions about partners and parenthood.

END.

Quora is an interesting website and potentially a very useful resource. I will keep visiting and answering questions when I feel I have something to offer. However, if you go to Quora you need to be careful when evaluating answers. Person X describes herself as a third year medical student, which suggests that medical schools are still teaching the AMA line on direct-to-consumer genetic tests, namely that a. they are pointless, b. consumers can’t handle them. That is why the AMA is lobbying the FDA to ban them. I disagree. That’s why I am asking people to sign this petition to the FDA.

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