KL and B-cell non-Hodgkin lymphoma: Mendelian randomization (MR) is a method based on Mendel first and second laws of genetic inheritance.[11] A genetic variant is considered an instrumental variable (IV) for a given exposure if it satisfies the IV assumptions.[12] So far, MR has been increasingly applied to examine causal inference in B-cell lymphoma.[13–15] However, the relationship between Klotho protein and B-cell lymphoma using the MR method has not yet been investigated.