List of Societies

Abstract

Holoprosencephaly (HPE) is a heterogeneous central nervous system (CNS) anomaly that results from a primary defect in induction and patterning of the rostral neural tube (basal forebrain), leading to varying degrees of incomplete separation of the cerebral hemispheres and facial anomalies. HPE is graded as alobar, semilobar, and lobar, and a mild version called middle interhemispheric variant of HPE. The variable facial anomalies are: (1) cyclopia, with or without proboscis; (2) ethmocephaly with ocular hypotelorism and proboscis located between the eyes; (3) cebocephaly with ocular hypotelorism and single-nostril nose; and (4) median cleft lip/palate (premaxillary agenesis) and ocular hypotelorism.The prevalence of severe HPE in embryonic population is approximately 50 : 10,000, whereas in nonselected fetal population it is approximately 1.26 : 10,000. HPE study populations differ depending on the age of the specimens, the time of the detection of HPE, the number of cases, identified subgroups (e.g., chromosomal, nonchromosomal, not karyotyped), and the type of population (selected or nonselected).There are various etiological factors involved in HPE (environmental and chromosomal factors, genetic syndromes). Depending on the etiology, a wide range of associated anomalies have been reported.US remains the primary imaging modality for examination of the fetal brain and thus HPE. MRI can be an important supplement in suspected fetal HPE, especially in the middle interhemispheric variant of HPE.There is a high prenatal and perinatal mortality rate of severe cases of isolated HPE. No treatment options are available. Surviving children with HPE have developmental disabilities correlating with the severity of brain malformation.