New data on hereditary microcephaly

Autosomal recessive primary microcephaly (MCPH) is a neurodevelopmental disorder, in which the circumference of the head is more than three standard deviations smaller than average. It is accompanied by mild-to-moderate mental retardation and, sometimes, mild epilepsy.

Five genes are known to be involved in MCPH; however, the gene ASPM accounts for about one-half of all cases of the disease. Researchers from France, Lebanon and Germany recently attempted to understand the different manifestations of the disease by studying 52 individuals from different families.

They found that while some patients at birth had a reduced head circumference by only two standard deviations, all patients showed slow postnatal head growth, with head circumference becoming even more than three standard deviations below average in the first year of life. The researchers suggest that the definition of MCPH be broadened to include newborns with mild microcephaly, while following up with serial head-circumference measurements after birth. This gradual decrease in the circumference of the head has not been documented before.

The researchers found that mental retardation varied widely in patients, with intelligence quotient (IQ) values ranging from 30 to 80 in some cases. They suggest that the degree of mental retardation might be related to the position of the mutation in ASPM. However, they stress that further testing on a larger sample of patients is needed to verify this.

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