Hi guys,

I'm a newbee on GWAS study and I saw sentences in a talk by John Quackenbush that

"97 SNPs explain 2.7% of BMI"

"All common SNPs may explain 20% of BMI"

What's the meaning of that percentage? How are the percentages calculated?

Thanks!

Tao

That probably means something like...

"You can determine someone's racial composition or location by looking at their SNPs. Those are both factors in BMI, which makes the SNPs correlated. These SNPs have no known causal relationship with BMI, but it's easy to use them to publish papers."

The rationale here is "heritability" which measures the proportion of the total phenotypic variation that's due to genetic variance. The percentage here is to describe the percentage of BMI variance due to genetic variance in the study cohort. (Total phenotypic variance = genetic variance + environmental variance). But I still don't know how is this calculated.

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