The FUCA1 gene provides instructions for making an enzyme called alpha-L-fucosidase. This enzyme is found in lysosomes, which are compartments in the cell that digest and recycle materials. Within lysosomes, this enzyme plays a role in the breakdown of complexes of sugar molecules (oligosaccharides) attached to certain proteins (glycoproteins) and fats (glycolipids). Alpha-L-fucosidase is responsible for cutting (cleaving) off a sugar molecule called fucose toward the end of the breakdown process.
At least 26 mutations in the FUCA1 gene have been found to cause fucosidosis. Most of these mutations result in an abnormally short, nonfunctional alpha-L-fucosidase enzyme. Without this enzyme, glycolipids and glycoproteins cannot be completely broken down. These partially broken down compounds accumulate in the lysosomes and cause cells throughout the body to malfunction. Brain cells are particularly sensitive to the buildup of glycolipids and glycoproteins, which can result in cell death. Loss of brain cells is thought to cause the neurological symptoms of fucosidosis. Accumulation of glycolipids and glycoproteins also occurs in other organs such as the liver, spleen, skin, heart, pancreas, and kidneys, contributing to the additional symptoms of fucosidosis.
- fucosidase, alpha-L- 1, tissue