The primary two-sample MR analysis revealed that 13 proteins were causally correlated with MM risk, with 6 showing positive associations (NAMPT, TIE1, CBR1, PDE4D, PAFAH1B2, and NCF2) and 7 showing inverse associations (FSTL1, PTPN4, SOCS3, GZMB, GPC1, C1QC, and FCGR3B). Here, FCGR3B is linked to Miyoshi myopathy.