Genotype-Phenotype Correlations, Geographic Distribution, and Treatment Outcomes in Congenital CD59 Deficiency: A Systematic Review.

Congenital/inherited CD59 deficiency is a rare, autosomal-recessive inborn error of immunity caused by biallelic loss-of-function variants in the CD59 gene. The encoded CD59 protein is a glycosylphosphatidylinositol (GPI)-anchored membrane inhibitor that protects host cells from complement-mediated lysis by preventing the formation of the membrane attack complex (MAC). Its deficiency leads to uncontrolled MAC deposition, primarily affecting red blood cells and neural tissues.