Molecular characteristics

C18orf32 encodes a 76-amino acid protein localized to the endoplasmic reticulum (ER) and lipid droplets (LDs), important for efficient GPI-inositol deacylation of GPI-anchored proteins (GPI-APs) by PGAP1 and may also be involved in lipid regulation. It is composed of a hydrophobic N-terminal region, necessary for recruitment to the ER and LDs, and an unstructured C-terminal region. A homozygous frameshift mutation has been reported in a 23-month-old child. The mutated allele has been found to escape from nonsense-mediated mRNA decay. GPI-inositol deacylation is important for GPI-APs to transition from the folding to transport state.