Partial trisomy 18 in a family with a translocation (18;21)(q21;q22)

A family is described in which 2 sibs had similar congenital abnormalities. Chromosome investigation of the mother and another child disclosed they were carriers of a translocation t(18;21)(q21;q22). The karyotype of one of the abnormal infants was determined and was found to be consistent with partial trisomy 18,46,XY,-21,+der (21),t(18;21) ((18pter leads to 18q21::21q22 leads to 2 lqter)mat.