In contrast to the Sas4 and Cep63 centrosome deficiency models, p53 activation and microcephaly caused by deletion of Smc5, that in mutated in Atelís syndrome and encodes part of the cohesin like SMC5/6 complex involved in DNA replication/repair, was rescued by loss of Chk2 or p53, but not by Usp28 or 53bp1 deficiency (Figure 2) (Atkins et al., 2020; Phan et al., 2021; Grange et al., 2022). This evidence concerns the gene SMC5 and microcephaly.