No effect on leptin levels under dimethyl fumarate treatment was found, both in a longitudinal and a cross-sectional study, between MS-affected and control groups (Baharnoori et al., 2021) Similarly, no effect on leptin levels for MS risk was identified, although there was an effect on MS risk combined with low vitamin D levels in a Mendelian randomization study (Harroud et al., 2021). The gene discussed is LEP; the disease is myeloid sarcoma.