While two markers are located in the previously reported FTO (intron 1; rs1421085; p = 2.99×10−8) and downstream of MC4R (rs17700144; p = 2.40×10−8), rs473034 indicates a new genetic locus for early onset extreme obesity located on chromosome 8p23.1 (p = 2.77×10−8) with the closest genes TNKS (tankyrase, TRF1-interacting, ankyrin-related ADP-ribose polymerase gene; ∼135 kb upstream of rs473034) and MSRA (methionine sulfoxide reductase A gene; ∼178 kb downstream of rs473034). The gene discussed is MC4R; the disease is obesity due to melanocortin 4 receptor deficiency.