Fetal holoprosencephaly: associated malformations and chromosomal defects.

In 38 fetuses with holoprosencephaly, cordocentesis and blood karyotyping was performed. The karyotype was normal in all 12 cases with isolated holoprosencephaly, and in all 5 with holoprosencephaly and facial defects only. In contrast, 11 of the 21 (52%) fetuses with extrafacial malformations were chromosomally abnormal [47xx+13, n = 6; 47xy+13, n = 2; 47xx+18, n = 1; 46xx-18+i(18q), n = 1; 46xy 21q-, n = 1]. In the chromosomally normal group, there was parental consanguinity in 2 cases and recurrence of holoprosencephaly in 3.