Two siblings with partial trisomy 15 and monosomy 21 associated with central nervous system anomalies

A sister and a brother with 46, XX (46, XY), -21, +der (15) (q22.1; q22.1) mat were reported whose mother had a karyotype of 46, XX, t(15; 21)(q22.1; 22.1) and was phenotypically normal. Both sibs were mentally retarded and dysmorphic. Moreover, the sister had a holoprosencephaly with congenital hydrocephalus, and the brother showed congenital hydrocephalus.