According to the clinical and laboratory findings, GPIBDs have been historically divided into two main subgroups: hyperphosphatasia with mental retardation syndrome (HPMRS) – a group of GPIBDs with elevated serum alkaline phosphatase activity (ALP) (mutations in PIGV, PGAP2, PGAP3, PIGO, PIGW, and PIGY) and multiple congenital anomalies hypotonia seizures (MCAHS) – with normal serum ALP (mutations in PIGA, PIGN, PIGT). However, the number of GPIBSDs that cannot be divided into these two groups is growing (Knaus et al., 2018). The gene discussed is PIGV; the disease is Elevated circulating alkaline phosphatase concentration.