MR Dictionary

A polymorphism is a genetic variant. The term is usually limited to variants that are moderately common (it is unusual for the term to be used when referring to rare variants).

Moderately common genetic variants tend to have modest effects on traits; therefore, the variance explained in that trait by common polymorphisms (including SNPs) is relatively small. Thus, MR studies using a small number of moderately common polymorphisms will require large sample sizes or the combination of many polymorphisms/ genetic variants (within a polygenic risk score (PRS)) for adequate statistical power.


Other terms in 'Useful genetic terms ':