Complete trisomy 22.

Two unrelated girls, aged 6 and 8 years, respectively, are presented with complete trisomy 22 in the absence of detectable mosaicism. In each case, the extra chromosome has been unambiguously identified as chromosome No. 22. The features which were consistent in both girls included: advanced maternal and paternal ages, a history of repeated abortions and stillbirths, normal birthweight with no gross post-natal growth retardation, mental retardation with further severe deterioration at 3-5 years of age, epilepsy (particularly motor seizures), hypotonia, neurological (especially cerebellar) deficit, and abnormal E.E.G. patterns. The physical stigmata comprised: frontal bossing, hypertelorism, bulbous nose, antimongoloid slant of the palpebral fissures, strabismus, long philtrum, large rotated protruding low-set auricles, pectus excavatum, and abnormal dermatoglyphics. The clinical course of the disorder was suggestive of a degenerative phenomenon of the central nervous system neurones.