An 18p21q Translocation in a Patient with Presumptive “Monosomy G”

A 3½-year-old retarded girl had multiple congenital anomalies. Cytogenetic analysis revealed a karyotype with a modal number of 2N = 45 and one member of the G (21-22) group consistently absent in lymphocytes and skin fibroblasts. The original diagnosis was “monosomy G” but reanalysis following fluorescence and Giemsa banding techniques demonstrated a translocation involving chromosomes 18 and 21 (45,XX,18-,21-, t[18p21q]). The patient therefore possesses the 18psyndrome and her phenotypic findings are compatible.