PNKP and microcephaly: Furthermore, it is known that NHEJ-related microcephalic syndromes can also be induced by mutations in the repair factor PNKP, which is mainly associated to two different syndromes: the microcephaly with seizures, hyperactivity, and developmental delay (MCSZ) and microcephaly associated with neurodegeneration and polyneuropathy (Shen et al., 2010; Poulton et al., 2013; Taniguchi-Ikeda et al., 2018).