Holoprosencephaly is a disorder caused by the failure of the prosencephalon (the embryonic forebrain) to sufficiently divide into the double lobes of the cerebral hemispheres. The result is a single-lobed brain structure and severe skull and facial defects. In most cases of holoprosencephaly, the malformations are so severe that babies die before birth. In less severe cases, babies are born with normal or near-normal brain development and facial deformities that may affect the eyes, nose, and upper lip. There are three classifications of holoprosencephaly. Alobar, in which the brain has not divided at all, is usually associated with severe facial deformities. Semilobar, in which the brain's hemispheres have somewhat divided, causes an intermediate form of the disorder. Lobar, in which there is considerable evidence of separate brain hemispheres, is the least severe form. In some cases of lobar holoprosencephaly the baby's brain may be nearly normal.The least severe of the facial anomalies is the median cleft lip (premaxillary agenesis). The most severe 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 proboscis (a tubular-shaped nose) located above the eye. The least common facial anomaly is ethmocephaly, in which a proboscis separates closely-set eyes. Cebocephaly, another facial anomaly, is characterized by a small, flattened nose with a single nostril situated below incomplete or underdeveloped closely-set eyes.
There is no standard course of treatment for holoprosencephaly. Treatment is symptomatic and supportive.
The prognosis for individuals with the disorder depends on the severity of the brain and facial deformities.
The NINDS supports and conducts a wide range of studies that focus on identifying and learning more about the factors involved in normal brain development. Recent research has identified specific genes that cause holoprosencephaly. The knowledge gained from these fundamental studies provides the foundation for understanding how to develop new ways to treat, and potentially prevent, this disorder.
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Carter Centers for Brain Research in Holoprosencephaly
Collaborative initiative created to gather, analyze, and share information about HPE. Maintains an international registry and an ongoing HPE database. Supports and conducts research and maintains a network of Centers of Excellence.
c/o Texas Scottish Rite Hospital
P.O. Box 190567
2222 Welborn Street
Dallas, TX 75219-9982
National Organization for Rare Disorders (NORD)
Federation of voluntary health organizations dedicated to helping people with rare "orphan" diseases and assisting the organizations that serve them. Committed to the identification, treatment, and cure of rare disorders through programs of education, advocacy, research, and service.
55 Kenosia Avenue
Danbury, CT 06810
The Arc of the United States
Promotes and protects the human rights of people with intellectual and developmental disabilities and actively supports their full inclusion and participation in the community throughout their lifetimes.
1825 K Street, NW
Washington, DC 20006
March of Dimes
Works to improve the health of babies by preventing birth defects and infant mortality through programs of research, community services, education, and advocacy.
1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: White Plains