What causes lobar holoprosencephaly?

Holoprosencephaly can be caused by mutations in any of at least 14 different genes; chromosome abnormalities; or agents that can cause birth defects ( teratogens ). It may also be a feature of several unique genetic syndromes . In many cases, the exact cause is unknown.

What is the genetic cause of holoprosencephaly?

The most common chromosomal abnormality associated with HPE is when there are 3 copies of chromosome 13 (trisomy 13), although a number of other chromosomal changes can also cause holoprosencephaly. In other children, holoprosencephaly is due to a change in a specific gene.

What affects holoprosencephaly?

Nonsyndromic holoprosencephaly is an abnormality of brain development that also affects the head and face. Normally, the brain divides into two halves (hemispheres ) during early development. Holoprosencephaly occurs when the brain fails to divide properly into the right and left hemispheres.

What is holoprosencephaly associated with?

Holoprosencephaly (HPE) is partial or complete failure of the forebrain to divide into hemispheres and can be an isolated finding or associated with a syndrome. Most cases of HPE are associated with a syndrome and roughly 40–60% of fetuses with HPE have trisomy 13 which is the most common etiology of HPE.

What is the life expectancy of someone with holoprosencephaly?

Developmental delay is present in the majority of individuals with the HPE spectrum. Severely affected children typically do not survive beyond early infancy, while a significant proportion of more mildly affected children survive past 12 months and many live into adulthood.

Is holoprosencephaly compatible with life?

Normally, the forebrain is formed and the face begins to develop in the fifth and sixth weeks of human pregnancy. The condition also occurs in other species. The condition can be mild or severe. Most cases are not compatible with life and result in fetal death in utero.

Can holoprosencephaly be cured?

There is no standard course of treatment for holoprosencephaly. Treatment is symptomatic and supportive. 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.

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How does holoprosencephaly cause a single lobed brain?

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.

How can diabetes increase the risk of holoprosencephaly?

Diabetes in the mother during the pregnancy can increase the risk of holoprosencephaly in the fetus. However, for most children, no known intrauterine exposure is identified that is causally related to holoprosencephaly in that child. Some children will have an identifiable genetic cause of holoprosencephaly.

What is the prognosis for alobar holoprosencephaly?

The prognosis depends on the sub-type. The alobar holoprosencephaly is the most severe type of the defect and the affected fetus are usually stillbirth, or die soon after birth, or during the first 6 months of life.

Who is at risk for holoprosencephaly during pregnancy?

Diabetes in the mother during the pregnancy can increase the risk of holoprosencephaly in the fetus. However, for most children, no known intrauterine exposure is identified that is causally related to holoprosencephaly in that child.