Mental retardation, malformation syndrome andpartial 7p monosomy [45, XX, tdic (7;15) (p21;p11)].

A mentally retarded and malformed girl is described. Her karyotype was 45,XX,tdic (7;15) (p21;p11), i.e. she was monosomic for bands 7p22 and a part of 7p21. Only one of the two centromeres of the dicentric chromosome appeared to be functioning. The C-band positive material was retained by both centromeres (or adjacent to them). However, the Cd-band positive structure was absent in the presumably nonfunctioning centromere region.