PIGA and multiple congenital anomalies-hypotonia-seizures syndrome 2: Multiple congenital anomalies–hypotonia–seizures syndrome-2 (MCAHS2) [OMIM: 300868], caused by mutations on the phosphatidylinositol-glycan-anchor biosynthesis class A (PIGA) gene, is an idiopathic X-linked recessive (XL) neurodevelopmental disorder.