In patients with aromatase deficiency, more than 30 distinct mutations have been identified in the CYP19A1 gene, including missense, nonsense, small deletions and insertions, splice-site mutations, and one large intragenic deletion (1,2,6,7,8,9,10,11,12,13,14,15,16). The gene discussed is CYP19A1; the disease is aromatase deficiency.