Trisomy 14 mosaicism in a translocation 14q15q carrier: probable dissociation and isochromosome formation.

A case of trisomy 14q mosaicism is described and compared with three other similar reported cases. The clinical picture is characterised by severe developmental retardation, failure to thrive, and somatic abnormalities including skeletal asymmetry, high arched or cleft palate, and low set dysplastic ears. The present chromosome imbalance probably resulted from dissociation of a balanced 14q15q translocation with subsequent formation of a 14q isochromosome.