Hyperphosphatasia with Impaired Intellectual Development Syndrome 4, also known as glycosylphosphatidylinositol biosynthesis defect 10, is related to hyperphosphatasia with impaired intellectual development syndrome 6 and hypotonia. An important gene associated with Hyperphosphatasia with Impaired Intellectual Development Syndrome 4 is PGAP3 (Post-GPI Attachment To Proteins Phospholipase 3). Affiliated tissues include bone marrow and cerebellum, and related phenotypes are hypotonia and global developmental delay