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Holoprosencephaly Reviewed 10-05-2001 Get Web page suited for printing Email this to a friend or colleague Studies with patients Table of Contents (click to jump to sections) What is Holoprosencephaly?Is there any treatment? What is the prognosis? What research is being done? Organizations What is Holoprosencephaly? Holoprosencephaly is a disorder caused by the failure of the prosencephalon (the forebrain of the embryo) to divide to form bilateral cerebral hemispheres, causing defects in the development of the face and in brain structure and function. Once called arhinencephaly, the disorder consists of a spectrum of defects or malformations of the brain and face. Most cases are associated with severe malformations of the brain which are incompatible with life and often cause spontaneous intrauterine death. At the other end of the spectrum are individuals with facial defects -- which may affect the eyes, nose, and upper lip -- and normal or near-normal brain development. Seizures and mental retardation may occur. The most severe of the facial anomalies is cyclopia, an abnormality characterized by a single eye, located in the area normally occupied by the root of the nose, and a missing nose or a nose in the form of a proboscis (a tubular appendage), located above the eye. Ethmocephaly is the least common facial anomaly. It consists of a proboscis separating narrow-set eyes with an absent nose and microphthalmia (abnormal smallness of one or both eyes). Cebocephaly, another facial anomaly, is characterized by a small, flattened nose with a single nostril situated below incomplete or underdeveloped closely set eyes. The least severe in the spectrum of facial anomalies is the median cleft lip also called premaxillary agenesis. There are three classifications of holoprosencephaly. Alobar, the most serious form in which the brain has no tendency to separate, is usually associated with severe facial anomalies. Semilobar, in which the brain's hemispheres have a slight tendency to separate, is an intermediate form of the disease. Lobar, in which there is considerable evidence of separate brain hemispheres, is the least severe form. In some cases of lobar holoprosencephaly the patient's brain may be nearly normal. Is there any treatment? What is the prognosis? What research is being done? The Arc of the United States
March of Dimes Birth Defects Foundation
Carter Centers for Research in Holoprosencephaly
National Organization for Rare Disorders (NORD)
National Institute of Child Health and Human
Development (NICHD)
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