[Asymmetric crying facies syndrome].

We report four cases with syndrome of asymmetric crying facies, analyzing particularly the etiology, embryology, and incidence of the congenital hypoplasia of depressor anguli oris muscle. In one of the cases, with multiple malformations, the patient had an abnormal karyotype, 47,XX, +i(18p). We stress the high incidence of associations with congenital malformations (eight fold the general population) and more specifically with congenital heart disease, musculoskeletal, and genito-urinary defects. The diagnosis of MDAO agenesis is basically clinic, being as differential diagnosis the paralysis of the 7th cranial nerve, defining it with electrophysiological techniques.