The causal effects of 79 gene and protein expression levels in blood were replicated in independent cohorts from a similar genetic ancestry group, including new potential T2D effector genes such as CPXM1, PTGES1 and FAM20B. Overall, we observed low ancestry-related heterogeneity of causal effects, suggesting they are likely shared across genetic ancestry groups. Here, FAM20B is linked to type 2 diabetes mellitus.