2011). The similar function of the cyclin-dependent kinase 5 regulatory subunit-associated protein 2 gene (CDK5RAP2, also named CEP215), located within the shared homozygous region on chromosome 9q33, and the description of recessive mutations in patients with primary microcephaly (Bond et al. 2005) prompted us to consider this gene as a highly relevant candidate. The gene discussed is CDK5RAP2; the disease is Primary microcephaly.