Human chromosome 9 sub-telomeric deletions involving the DMRT1 locus have been associated with 46,XY sex reversal and gonadal dysgenesis in XY individuals [13], while smaller deletions and sequence variants of DMRT1 have been identified in men with phenotypes ranging from syndromic XY gonadal dysgenesis to azoospermia without signs of gonadal dysgenesis [14–20]. The gene discussed is DMRT1; the disease is gonadal dysgenesis.