In this nationally representative study of adolescents, we identify two nominally significant obesity susceptibility variants in EA, rs2112347 (POC5) and rs571312 (MC4R), and one Bonferroni corrected significant variant in HA, rs1514175 (TNNI3K), which showed a comparatively stronger association in smokers vs. nonsmokers. The gene discussed is MC4R; the disease is obesity due to melanocortin 4 receptor deficiency.