Interestingly, mutations in the centrosomal proteins CEP152 (MCPH4) and CENPJ (MCPH6), which are thought to interact with each other during centriole biogenesis [11], [12], have also been associated with primary autosomal recessive microcephaly, a genetically heterogeneous condition caused by mutation of one of eight loci (MCPH1–8; [13], [14], [15]) result in clinically indistinguishable features that include mental retardation and a severely reduced brain size of greater than two standard deviations below the average. Here, CPAP is linked to autosomal recessive primary microcephaly.