An anencephalic infant with holoprosencephalic facies and ring chromos
ome 18 [r(18)] is reported with review of the pertinent literature. Al
though the association of anencephaly and holoprosencephalic facies is
well established this is the first instance of an accompanying karyot
ypic abnormality. Review of other r(18) cases suggests that this is no
t a coincidental finding. Karyotype analysis appears warranted in case
s of anencephaly with holoprosencephalic facies.