In those syndromes, no obvious genotype–phenotype relationship has been established to date, besides the importance of the SHOX gene situated in the pseudo-autosomal region and therefore expressed on all sex chromosomes because it does not undergo X inactivation, and which has been shown to impact height and other skeletal changes, especially seen in patients with Turner syndrome [203,204], and explains part of the short stature in Turner syndrome and increased height in conditions with supernumerary sex chromosomes [205]. The gene discussed is SHOX; the disease is Turner syndrome.