Chromosome 15 abnormality in a mentally retarded adult.

et al., 1961; Lubs, Koenig, and Brandt, 1961) has recently been identified with the late-replicating, distally labelled, D1 (13) pair (Yunis, Hook, and Mayer, 1964b; Yunis et al., 1964a; Yunis and Hook, 1966; Gianne]li, 1965; Giannelli and Howlett, 1966; Lee et al., 1966; Wilson et al., 1967; Bloom and Gerald, 1968). This report concerns a retarded adult with some manifestations of the D1 syndrome, in whom the abnormality involves a different D chromosome.