One of our earlier works on the obesity gene of FTO [44], by way of demonstrating that an FTO variant rs1421085 associates with total body water and soft lean mass through interaction with ghrelin and apolipoproteins in the Arab population, illustrates the insight that deep phenotyping can bring to transferability of GWA-identified association signals to the ethnic population. The gene discussed is FTO; the disease is obesity due to melanocortin 4 receptor deficiency.