Autosomal recessive primary microcephaly (MCPH) is a hereditary form of microcephaly and mental retardation. The diagnosis can be suspected from the clinical findings.
Inheritance: autosomal recessive
Clinical features:
(1) congenital microcephaly
(2) head circumference at least 4 SD below mean for age and gender (and race)
(3) mental retardation
(4) no neurologic findings with exception of rare patients with seizures. There is no evidence of spasticity or progessive cognitive decline.
(5) usually normal for height, weight, appearance, chromosome analysis and brain scan. Exception is for mutations in MCPH1 which may be associated with decreased height, periventricular neuronal heterotopia on NMR scan and minor changes in cytogenetic analysis
Patients with MCPH will have mutations in one of 6 loci.
Locus
Chromosome
Gene
MCPH1
8p22-pter
microcephalin
MCPH2
19q13.1-13.2
unknown
MCPH3
9q34
CDK5RAP2
MCPH4
15q15-q21
unknown
MCPH5
1q31
ASPM
MCPH6
13q12.2
CENPJ
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