PIGV and hyperphosphatasia-intellectual disability syndrome: Missense mutations in genes encoding enzymes catalyzing various steps of GPI anchor biosynthesis, such as PIGW that catalyzes attachment of acyl group to phosphatidylinositiol [15,16], PIGV that catalyzes transfer of second mannose to GPI intermediate [17,18], PIGT that attaches GPI to proteins [19] and PGAP2 that modifies the phospholipid tail of PI [20] result in congenital diseases known as hyperphosphatasia mental retardation syndrome (HPMRS), Hirschprung disease, morphological malformation and renal anomalies [21,22,23,24].