Phosphatidylinositol glycan biosynthesis class A congenital disorder of glycosylation (PIGA-CDG) is an ultrarare, X-linked recessive disorder caused by partial loss of function mutations in the PIGA gene (Johnston et al. 2012; Kato et al. 2014; van der Crabben et al. 2014; Bayat et al. 2020). The gene discussed is PIGA; the disease is congenital disorder of glycosylation.