The B3GLCT gene (formerly known as B3GALTL) provides instructions for making an enzyme called beta 3-glucosyltransferase (B3Glc-T), which is involved in the complex process of adding sugar molecules to proteins (glycosylation). Glycosylation modifies proteins so they can perform a wider variety of functions. The B3Glc-T enzyme is involved in a two-step glycosylation pathway that results in the formation of a sugar structure, made up of the sugars fucose and glucose, on a specific location of several different proteins. The B3Glc-T enzyme is responsible for the second step, which adds a glucose molecule to the fucose molecule already attached to the protein. The B3GLCT gene is normally turned on (active) in most cells of the body, which suggests that the B3Glc-T enzyme plays an important role across many cell types.
At least 10 mutations that cause Peters plus syndrome have been identified in the B3GLCT gene. Peters plus syndrome is characterized by eye abnormalities, short stature, intellectual disability, and distinctive facial features. The most common B3GLCT gene mutation replaces the DNA building block (nucleotide) guanine with the nucleotide adenine near an area of the gene called exon 8 (written as 660+1G>A). This mutation disrupts how genetic information is pieced together to produce the B3Glc-T enzyme. The resulting enzyme is abnormally short and nonfunctional. It is unclear how the loss of functional B3Glc-T enzyme leads to the signs and symptoms of Peters plus syndrome, but impaired glycosylation likely disrupts the function of many proteins, which may contribute to the variety of features.
- beta 1,3-galactosyltransferase-like