Congenital Hypoplasia of Depressor Angularis Oris Muscle.

Papadatos, C., Alexiou, D., Nicolopoulos, D., Mikropoulos, H., and Hadzigeorgiou, E. (1974). Archives of Disease in Childhood, 49, 927. Congenital hypoplasia of depressor anguli oris muscle: a genetically determined condition? The frequency of hypoplasia of the depressor anguli oris muscle was 37 cases among 4 530 consecutive births (8 -2 %). Diagnosis was based on clinical and electromyographic studies. Severe congenital anomalies were detected in 3 of the 37 cases, while another 3 newborns had minor congenital defects. In 17 of the 37 cases there were firstor second-degree relatives with lower lip asymmetry. A minimum of 13 out of the 74 parents of the probands were affected. The high incidence of affection among first-degree relatives of the probands is strong evidence of hereditary factors playing a role in the aetiology of this anomaly.