A patient with a complex chromosomal rearrangement is described. Fluorescent microscopy after staining with quinacrine mustard revealed that what appeared to be a simple inversion of a G chromosome as judged by conventional cytogenetic techniques actually represented a probable reciprocal translocation resulting in monosomy-21 and trisomy of the centric portion of another chromosome.
The congenital abnormalities noted were: hypertelorism, epicanthus, small ears, small mouth, high-arched palate, flat nasal-bridge, and short neck. Several joints, including those in the fingers and toes, were malformed and limited in their movements. There was a heart anomaly interpreted as a ventricular septal defect and psychomotor development at the age of 14 months was clearly retarded.
The clinical features of this patient were compared with the cases reported by others in which total or partial G-monosomy was claimed.