TBX3 and ulnar-mammary syndrome: The other variant, rs8853, is correlated (r2 = 0.64) with rs11067228 reported to associate with serum levels of prostate-specific antigen (PSA)18 and it is located in the 3′-untranslated region (UTR) of TBX3, belonging to the same gene family as TBX5. Germline mutations in TBX3 underlie ulnar mammary syndrome, a rare pleiotropic developmental disorder characterized by altered: upper limbs, apocrine and mammary glands, and genitals19.