Autosomal recessive primary microcephaly (MCPH) is a rare genetically heterogeneous disorder of neurogenic brain development with features of reduced head circumference at birth with no gross anomalies of brain architecture and variable degrees of intellectual impairment. It is more common in specific populations, e.g. northern Pakistanis. Consanguinity appears to play a role in incidence. Patients have a reduction in head circumference at birth of at least 2 standard deviations below ethnically matched, age- and sex-related mean values. Caused by mutations in MCPH1, WDR62, CDK5RAP2, CEP152, ASPM, CENPJ, STIL, CEP63, CEP135 , CASC5 and PHC1. These mutations appear to lead to reduced generation of cerebral cortical neurons during embryonic neurogenesis. Inheritance is autosomal recessive.