Some genetic models have been obtained in order to study either the idiopathic or the syndromic or the genetic variants of HypoPT; an example is the knockout model of mice deficient in either the genes Crkol (Crkol−/−) or Tbx1 (Tbx1−/−), which showed the same severe abnormalities of the DiGeorge syndrome, including hypoplasia of the parathyroid gland [32,33,34,35]. The gene discussed is TBX1; the disease is 22q11.2 deletion syndrome.