Microcephaly

Microcephaly is a neurodevelopmental disorder in which the circumference of the head is more than two standard deviations smaller than average for the person's age and sex. Microcephaly may be congenital or it may develop in the first few years of life. The disorder may stem from a wide variety of conditions that cause abnormal growth of the brain, or from syndromes associated with chromosomal abnormalities. Two copies of a loss-of-function mutation in one of the microcephalin genes causes primary microcephaly.

In general, life expectancy for individuals with microcephaly is reduced and the prognosis for normal brain function is poor. The prognosis varies depending on the presence of associated abnormalities.