LIG4 and immune system disorder: LIG4 and XLF/Cernunnos syndromes are rare autosomal recessive disorders with symptoms including microcephaly, severe growth delay, “bird-like” facial appearance, bony malformations, immunodeficiency and increased cellular sensitivity to IR (Çipe et al., 2014; Altmann and Gennery, 2016; Recio et al., 2019; Gerasimou et al., 2020).