The discrepancy between microcephaly of Cenpjtm/tm mice and CENPJ-Seckel patients may instead be due to the hypomorphic nature of the Cenpjtm1a(EUCOMM)Wtsi allele or by the rapid evolution of the Cenpj gene between mice (80% sequence identity) and humans; the human CENPJ protein may be more efficient at regulating neurogenesis than that of the mouse [67]. This evidence concerns the gene CPAP and microcephaly.