Neonatal death in cousins with trisomy 10q and monosomy 4p due to a familial translocation.

Two cousins with trisomy for a part of the long arm of chromosome 10 and monosomy for the distal portion of the short arm of chromosome 4 are reported. These infants had severe, neonatally lethal multiple malformations. Certain of these malformations--including severe lower limb reductions, marked ophthalmologic anomalies and certain craniofacial features--are inconsistent with either a simple additive effect of the two component chromosomal anomalies, or chromosomal "epistasis" that would result in observing the phenotypic effect of only one of the chromosomal aberrations. Rather a synergistic effect of these two karyotypic anomalies has resulted in unique phenotypic features.