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Family history misses cases......so what?

Posted Nov 13 2008 4:22am

In the last two days I have been fighting off false claims from certain employees of certain unnamed DTC genetic testing companies. Their claims/anecdotes.......

"Family history is not that good......it misses alot.....which is why SNP testing is superior"


Huh???? Other claims "The false negative rate on family history is surprisingly high....which is why need SNP testing"

Says who?

I decided to take matters into my own hands........I turned to pubmed......


Maybe they were right? Maybe there was a whole set of data implicating that a properly ascertained family history misses risks.......especially controlled for environment. Why controlled? Any idiot knows that if you smoke, eat poorly and don't exercise you are likely to get a chronic disease even if it doesn't run in your family, so that doesn't really count as a false negative....I would be surprised if any one did this set of studies, but nonetheless I looked at this the scientific way......lit review.....


I first just searched family history.....what did I find? 54,000 articles.....phew.....someone has actually studied family history ;)


For interest sake how many GWAS papers are there? type in GWAS and you get a whopping 79.........hmmmmmmm...let's say I missed half.....that still is 160 VERSUS 54,000

Give me a break.......

One family historystudy reported on college freshmen girlswho had a family history of drinking problems....guess what? They ended up drinkning more......There's a shocker!!

But seriously, I want to know how often Family history falls short. There must be something to it I suppose...why else would most physicians report "Family History Non-Contributory" on history and physicals? I suspect it is the fact that non-contributory means "I can't interpret or take it, therefore it contributes nothing to my assessment"


I do know that often with strong monogenetic disease you can get a negative family history.....especially in the case of new autosomal dominant disease or recessive disease.....but this is often because these patients die before they can have kids.....but in heart attack or multiple sclerosis or even diabetes, the reduction in fecundity can't be that strong......


We even see reports inresponse to chemo and cancer stagehaving family history inplications....

Among patients with stage III colon cancer receiving adjuvant chemotherapy, a family history of colorectal cancer is associated with a significant reduction in cancer recurrence and death.


So is it true? Is my equation Genome + Environment = Phenome + Metabolome hopelessly proven wrong???? You see, I say Genome + Environment is roughly equal to.......Family History

Provided that the environmental component is not greater that the genomic component this should work out pretty nicley.....unless of course you move to Chernobyl or decide to live in a Benzene factory....

So could I be wrong? Could Family history be non-contributory......In 3 cases I say yes....


1. If you are adopted, estranged or "just didn't talk about it"

2. If you cannot obtain medical records to verify self report of family history

3. If you believe in spontaneous generation


In Number One, that is likely to change as the environment of sharing health information changes.....I already see it.......30 year old women know family history better than 60 year old women do.........


Well, aside from these 4 topics.......not a single report of family history being totally useless

1. Rare chromosomal anomalies that occur in less that 1% of the population

2. Rare monogenic disease

3. Congenital Anomalies

4. Severe Trauma


But other than that......


54,000 articles vs maybe 160 articles.......Family history wins.....just about everytime.....and in common chronic disease the evidence is overwhelming.....why? Often multifactorial disease relies on multiple genetic combinations, inherited together....what an easier way to inherit these combinations than when passing them on through families.....


So the next time someone tells you that SNPs are better than family history you tell them......54,000 articles is a lot more to go on than 160....unless of course they are talking about the 4 categories where it is not so useful......


The last time I checked......that's not where DTC is.....


The Sherpa Says: Anecdotal evidence of n less than 100 is highly suspect and is likely to be used as a marketing ploy and to fool you......The "Sound of Science" is merely just the sound ofsilver tongued scientific shennanigans and Fads........Don't believe the hype....Family history IS the cheapest Whole Genome Analysis we have......... Not Family Genome Scans......Family History, plain and simple.....plus it has 54,000 Articles of research 270 times more study than SNP scans.......





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