Banding identification of chromosomal abnormalities in four patients: ring (6), translocation (2q-;15q+), translocation (21q;21q) and deletion (22q-).

Four children with mental deficiency and different chromosomal errors, previously reported, have been restudied with the use of the G-banding technique. The errors include ring-6, t(2q-; 15+), t(21q;21q) and 22q-.