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.
Cohen MM, Putnam TI. An 18p21q Translocation in a Patient With Presumptive "Monosomy G". Am J Dis Child. 1972;124(6):908-910. doi:10.1001/archpedi.1972.02110180110016