Previous studies in rodents have indicated that the facial changes of
fetal alcohol syndrome (FAS) closely resemble those of a mild form of
holoprosencephaly. In order to examine this relationship in non-human primates, we evaluated a 133-day gestation macaque (Macaca nemestrina) with
holoprosencephaly, median
cleft lip and palate, and
encephalocele. The mother had been given
ethanol once per week (1.8 g/kg
body weight) from weeks 2 to 19 postconception. Diagnosis of
holoprosencephaly was made following ultrasound evaluation for
polyhydramnios and delivery of the female fetus by
caesarean section. Another fetus of identical age was delivered by
caesarean section for use as a control. Both fetuses were studied by anthropometric, gross, radiographic, and histologic techniques. In the fetus exposed to alcohol, no extracranial anomalies were identified and the karyotype was normal. The brain was micrencephalic, with absent olfactory bulbs, tracts, optic nerves and chiasma, fused frontal lobes, and a single, dilated lateral ventricle; a parietooccipital
encephalocele consisted of thin, dysplastic cortex bordering the ventricle; the cerebellum was dysplastic and superiorly displaced. Within the craniofacial complex,
anophthalmia was bilateral; premaxillary components were absent, palatal shelves separate, the maxillae closeset, and the ethmoid bone small and deformed. Most of these defects are similar to those encountered in humans with
holoprosencephaly and support the hypothesis of shared etiologic and pathogenetic relations between the facial anomalies of
fetal alcohol syndrome and
holoprosencephaly.