Autosomal recessive primary microcephaly

Alternate names

Microcephalia vera; Microcephaly vera; True microcephaly; MCPH

Definition

Autosomal recessive primary microcephaly (often shortened to MCPH, which stands for "microcephaly primary hereditary") is a condition in which infants are born with a very small head and a small brain. The term "microcephaly" comes from the Greek words for "small head."

Epidemiology

The prevalence of all forms of microcephaly that are present from birth (primary microcephaly) ranges from 1 in 30,000 to 1 in 250,000 newborns worldwide. About 200 families with MCPH have been reported in the medical literature. This condition is more common in several specific populations, such as in northern Pakistan, where it affects an estimated 1 in 10,000 newborns.

Cause

• MCPH can result from mutations in at least seven genes. Mutations in the ASPM gene are the most common cause of the disorder, accounting for about half of all cases.
• The genes associated with MCPH play important roles in early brain development, particularly in determining brain size.
• Studies suggest that the proteins produced from many of these genes help regulate cell division in the developing brain.

Gene mutations

• Mutations in any of the genes associated with MCPH impair early brain development.
• As a result, affected infants have fewer nerve cells (neurons) than normal and are born with an unusually small brain.
• The reduced brain size underlies the small head size, intellectual disability, and developmental delays seen in many affected individuals.

Inheritance

Autosomal recessive inheritance, a 25% chance

This condition is inherited in an autosomal recessive pattern.

Signs and symptoms

• MCPH causes mild to moderate intellectual disability, which does not worsen with age, and also mild delayed speech, motor, and language skills.
• Some people with MCPH have a narrow, sloping forehead; mild seizures; problems with attention or behavior; or short stature compared to others in their family.
• It normally does not affect any other major organ systems or cause other health problems.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Global developmental delay
• Gray matter heterotopia
• Intellectual disability, severe(Early and severe mental retardation)
• Microcephaly(Abnormally small skull)
• Short stature(Decreased body height)
• Sloping forehead(Inclined forehead)
• Thin upper lip vermilion(Thin upper lip)
• Upslanted palpebral fissure(Upward slanting of the opening between the eyelids)

30%-79% of people have these symptoms

• Abnormal cortical bone morphology
• Agenesis of corpus callosum
• Hyperreflexia(Increased reflexes)
• Hypoplasia of the frontal lobes(Underdeveloped frontal lobe)
• Pachygyria(Fewer and broader ridges in brain)
• Unilateral renal agenesis(Absent kidney on one side)
• Ventriculomegaly
• Vesicoureteral reflux

Treatment

There is no cure and treatment is supportive.

NIH genetic and rare disease info

• NIH info on Autosomal recessive primary microcephaly

Autosomal recessive primary microcephaly is a rare disease.

Autosomal recessive primary microcephaly Resources
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