Our patients shared multiple homozygous genomic regions; ten shared regions were >1 Mb in length and constituted 0.99% of the genome. DCAF17, encoding a transmembrane nuclear protein of uncertain function, was the only gene identified in a homozygous region known to cause hypogonadotropic hypogonadism. DCAF17 mutations are associated with Woodhouse-Sakati syndrome, a rare disorder characterized by alopecia, hypogonadotropic hypogonadism, sensorineural hearing loss, diabetes mellitus, and extrapyramidal movements. This evidence concerns the gene DCAF17 and diabetes mellitus.