Molecular characteristics
Many cell-surface proteins are anchored to the membrane via glycosylphosphatidylinositol (GPI). There are at least 27 genes involved in biosynthesis and remodeling of GPI anchors. Mutations in twenty of these genes have been reported to cause decreased expression of GPI anchored proteins (GPI-APs) on the cell surface or expression with abnormal structures of GPI-anchor and to cause autosomal-recessive forms of intellectual disability. These are called inherited GPI deficiencies (IGDs). PGAP1 deficiency did not affect the surface
expression of GPI-APs but expressed structurally abnormal GPI-APs with the
acylated inositol.
Suspected pathogenicity
One of the characters of the GPI-APs is that their expression is regulated by being cleaved and released from the cell surface by some lipase. Those released proteins are also known to function on the different cells. PGAP1 deficient cells are resistant for the cleavage by lipase, which may cause the neurological abnormalities.