Illuminating mucopolysaccharidosis type III

By Dr Nicola Davies

Mucopolysaccharidosis type III (MPS III), also known as Sanfilippo syndrome, is a lysosomal storage disorder that affects fetal brain development. It is caused by the absence of enzymes responsible for breaking down a heparan sulphate, which belongs to a group of complex sugars known as glycosaminoglycans.1,2 Lack of these enzymes leads to the accumulation of the sugar in the cells of the central nervous system (CNS), which in turn leads to developmental problems.

There are four MPS III subtypes, each caused by a mutation in four different genes that each encode one of four enzymes responsible for recycling heparan sulphate:1,3