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Genetic and Rare Diseases Information Center (GARD)

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Other Names for this Disease
  • HPE
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Your Question

What is the life expectancy for a baby with semi-lobar holoprosencephaly? What are the most common defects?

Our Answer

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What is holoprosencephaly?

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. There are four types of holoprosencephaly according to the degree of brain division. From most to least severe, the types are known as alobar, semi-lobar, lobar, and middle interhemispheric variant (MIHV). The most severely affected individuals have one central eye (cyclopia) and a tubular nasal structure (proboscis) located above the eye. In the less severe forms, the brain is partially divided and the eyes are usually set close together (hypotelorism). Holoprosencephaly can be caused by mutations in a single gene, chromosome abnormalities, or substances that cause birth defects (teratogens).[1]
Last updated: 9/30/2010

What are the signs and symptoms of semi-lobar holoprosencephaly?

Semi-lobar holoprosencephaly occurs when the left side of the brain is fused to the right side in the areas of the brain known as the frontal and parietal lobes. Also, the dividing line between the right and left hemispheres of the brain (the interhemispheric fissure) is only present in the back. Individuals with semi-lobar holoprosencephaly may have eyes that are set close together (hypotelorism), and their eyeballs may be abnormally small (microphthalmia) or absent (anophthalmia). Additional features may include a flattened bridge and tip of the nose, one nostril, a cleft lip that occurs in the middle (median cleft lip) or on both sides (bilateral cleft lip), and a cleft palate.[2]

Other signs and symptoms commonly observed in children with holoprosencephaly include seizures, hydrocephalus, neural tube defects, pituitary dysfunction, short stature, feeding difficulties, and instability of temperature, heart rate, and respiration. Most people with holoprosencephaly have developmental delay and intellectual disability, the severity of which is related to the severity of the brain malformation.[2]
Last updated: 9/30/2010

What is the life expectancy for semi-lobar holoprosencephaly?

A common misperception is that children with holoprosencephaly do not survive beyond early infancy.[2] While this is the case for the most severely affected children, a significant proportion of more mildly affected children (as well as some severely affected children) survive past age 12 months.[2] More than 50 percent of children with semi-lobar or lobar holoprosencephaly without significant malformations of other organs are alive at age 12 months.[2] The life expectancy for individuals with semi-lobar holoprosencephaly depends on the underlying cause of the condition and the presence of associated anomalies.[3]
Last updated: 10/1/2010