As well as obesity, a number of genes located on the DS critical region of chromosome 21, including dual-specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A) and regulator of calcineurin 1 (RCAN1), are being investigated and are thought to contribute to diabetes in DS (13,14). The gene discussed is DYRK1A; the disease is obesity due to melanocortin 4 receptor deficiency.