Alobar holoprosencephaly: report of two cases with unusual findings.

Holoprosencephaly, a disorder resulting from failure of cleavage or incomplete differentiation of the forebrain structures at various levels or to various degrees, is related to hereditary factors, chromosomal anomalies, cytogenetic abnormalities, and environmental teratogenic factors. We report on 2 cases of alobar holoprosencephaly, with similar physical findings, including microcephaly, microphthalmia, cebocephalus, choanal atresia, pseudo cleft palate, distended abdomen, and acrocyanosis. The brain echogram of these 2 patients demonstrated fused thalami and a single large U-shaped ventricular cavity. Chromosome studies of these 2 patients were normal. The findings of the autopsies confirmed the clinical presentations. One of our cases had a clinical picture similar to that of holoprosencephaly-polydactyly syndrome. The other had the rare anatomical finding of a polylobuated spleen. Because of the poor prognosis of alobar holoprosencephaly, early prenatal diagnosis is recommended.