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Holoprosencephaly
What is Holoprosencephaly?
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.
Is there any treatment?
There is no standard course of treatment for holoprosencephaly. Treatment is
symptomatic and supportive.
What is the prognosis?
The prognosis for individuals with the disorder depends on the severity of
the brain and facial deformities.
What research is being done?
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.
Organizations
Carter Centers for Research in Holoprosencephaly
c/o Texas Scottish Rite Hospital P.O. Box 190567
2222 Welborn Street
Dallas, TX 75219-9982
hpe@tsrh.org
http://www.stanford.edu/group/hpe
Tel: 214-559-8411
Fax: 214-559-8383
National Organization for Rare Disorders (NORD)
P.O. Box 1968
(55 Kenosia Avenue)
Danbury, CT 06813-1968
orphan@rarediseases.org
http://www.rarediseases.org
Tel: 203-744-0100 Voice Mail 800-999-NORD (6673)
Fax: 203-798-2291
The Arc of the United States
1010 Wayne Avenue, Suite 650
Silver Spring, MD 20910
Info@thearc.org
http://www.thearc.org
Tel: 301-565-3842
Fax: 301-565-3843 or -5342
March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
askus@marchofdimes.com
http://www.marchofdimes.com
Tel: 914-428-7100 888-MODIMES (663-4637)
Fax: 914-428-8203
Source: National Institutes of Health; National Institute of
Neurological Disorders and Stroke
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