GPR151 and type 2 diabetes mellitus: Here, we (i) identify homozygous carriers of GPR151 plof variants, including those specific to South Asia, (ii) confirm in vitro that these variants are loss-of-function, (iii) test if GPR151 knockouts are associated with BMI, T2D, or other metabolic traits, and (iv) characterize Gpr151-/- mice for body weight.