Trisomy 22. Two new cases and delineation of the phenotype.

Two unrelated children, not affected with Down's syndrome, with strikingly similar phenotypes and an extra G-like chromosome are presented. Quinacrine and trypsin-Giemsa banding identified the extra chromosome as No. 22. The phenotype of these patients and the review of 15 additional similar cases from the literature permit a definition of the cardinal features of trisomy 22; mental and growth retardation, microcephaly and craniofacial asymmetry, strabismus, beaked and prominent nose, long philtrum, cleft palate, micrognathia, large low set ears with preauricular tags and/or pits, long slender fingers, congenital heart disease, inguinal hernia, and hip dislocation.