POLA1 and Immunodeficiency: Finally, mutations in genes encoding subunits of the replicative DNA polymerases POLA1, POLD1, POLD2, POLE, and POLE2 have implicated components of the active replisome in primordial dwarfism, often with immune deficiency, and in the case of POLE, adrenal failure (Pachlopnik Schmid et al. 2012; Thiffault et al. 2015; Frugoni et al. 2016; Logan et al. 2018; Conde et al. 2019; Van Esch et al. 2019).