Category:Causes of HPE
From Holoprosencephaly
What causes Holoprosencephaly?
The cause of Holoprosencephaly (HPE) is currently unknown. Often, no specific cause can be identified. Suggested risk factors include maternal diabetes, infections during pregnancy (syphilis, toxoplasmosis, rubella, herpes, cytomegalovirus), and various drugs taken during pregnancy (alcohol, aspirin, lithium, thorazine, anticonvulsants, hormones, retinoic acid). Women with previous pregnancy loss and first trimester bleeding are also more likely to have a child diagnosed with Holoprosencephaly.
Although many children with Holoprosencephaly have normal chromosomes, specific chromosomal abnormalities have been identified in some patients. There is evidence that in some families, HPE is inherited (autosomal dominant as well as autosomal or X-linked recessive inheritance). Features consistent with familial transmission of the disease (e.g., a single central maxillary incisor) should be carefully assessed in parents and family members.
Several genes have been identified that play a role in Holoprosencephaly, specifically sonic hedgehog, ZIC2, TGIF, and SIX3.
How common is this defect?
It is estimated that Holoprosencephaly affects between 1 in 5,000-10,000 live births. Since many pregnancies with a fetus diagnosed with HPE end in miscarriage, the frequency of HPE among all pregnancies may be as high as 1 in 200-250. Studies in the past have indicated that 3% of all fetuses with Holoprosencephaly survive to delivery and the vast majority of these infants do not survive past the first six months of life, however current statistics are not available.
The prognosis for a child diagnosed with Holoprosencephaly depends on the type of HPE and the presence of associated anomalies. The most severely affected children may live several months or years and the least affected may live a normal life span.
What are the risks of reoccurrence?
The risk of reoccurrence is small in most families, but genetic counseling is recommended.
Click here to read about: New Diagnosis of Holoprosencephaly
Click here to read what specialists have to say about caring for children with Holoprosencephaly: Doctor Q&A
Resources
http://www.stanford.edu/group/hpe/about/
