Karyotype 47,XXY,18p--in a newborn child with holoprosencephaly.

This may be the first reported case of a 47,XXY,18p--("Klinefelter-de Grouchy I syndrome"), in a post-term male neonate. The child had a dysmorphic facies, a small nose with a single orifice, cranial malformations and an alobar holoprosencephaly. These symptoms corresponded with the known phenotypic variants of the simple 18p--anomaly. The karyotypes of both parents were normal.