A supernumerary "G" like chromosome originating from a maternal 13;15 translocation in a nondysmorphic, retarded girl.

This paper describes a retarded girl who had a severe seizure disorder and a few minor anomalies, and who was found to have a "G-sized" supernumerary chromosome in all her cells which were examined. Studies of the patient's and her parents' chromosomes by a variety of techniques suggest that the supernumerary chromosome arose following a prezygotic maternal 13;15 translocation.