In general, loss of the short arm of the X chromosome (Xp) will result in a short stature with typical skeletal changes observed in individuals with TS, in part as a result of haploinsufficiency of the short stature–homeobox (SHOX) gene located in the pseudoautosomal region (PAR1) of Y and Xp [38]. The gene discussed is SHOX; the disease is Timothy syndrome.