Genetic Study and Prenatal Diagnosis of Inherited Glycosylphosphatidylinositol Disorders due to Novel Variants in Phosphatidylinositol Glycan Genes

Inherited glycosylphosphatidylinositol deficiency disorders (IGDs) are a group of rare recessive genetic conditions characterised by developmental delays and an early onset epilepsy caused by disruptions in the glycosylphosphatidylinositol-anchored biosynthetic pathway. In this study, we identified eight variants in phosphatidyl inositol glycan (PIG) genes from four IGDs families through whole-exome sequencing (WES). The variants included one in PIGA, two in PIGW and five in PIGN, with five being novel variants. Functional analysis confirmed the pathogenicity of the PIGN (c.1117-12C>G) and PIGW (c.1112delT and c.659T>G) variants. According to ACMG/AMP guidelines, four novel variants were classified as pathogenic or likely pathogenic. Families I and III successfully delivered healthy children after prenatal diagnosis. This study identified the pathogenic causes of four IGD pedigrees, expanded the mutation spectrum of PIG genes and provided a theoretical basis for reproductive interventions in such families.