CAIS patients have a male karyotype with female phenotype and despite testicular production of testosterone (T) and dihydrotestosterone (DHT), they do not develop either male genitalia or male secondary sexual characters; furthermore, since the testicular Sertoli cells produce Müllerian-inhibiting factor (MIF), they do not develop Müllerian structures. The gene discussed is MIF; the disease is complete androgen insensitivity syndrome.