A recent study identified two rare missense mutations in NRG4, Nrg4 E47Q, and Nrg4 R44H, by whole-exome sequencing of 224 subjects with obesity and exome genotyping of 2,388 participants from the Shanghai Obesity Study (Li et al., 2021). The gene discussed is NRG4; the disease is obesity due to melanocortin 4 receptor deficiency.