Genetic risk score
= Genetic risk score
{title2=$G_{\rm score}=\sum_j w_jG_j$}
A genetic risk score combines allele counts from several <genetic variants>, usually using specified weights. In <Mendelian randomization> it can act as a combined <instrumental variable> for an <exposure>; interpretation still requires <instrument relevance>, <instrumental-variable independence>, and the <exclusion restriction>.