Mucopolysaccharidoses
The mucopolysaccharidoses (MPS) are lysosomal storage disorders caused by the deficiency of enzymes required for the stepwise breakdown of glycosaminoglycans (GAGs), previously known as mucopolysaccharides (1-5). Fragments of partially degraded GAGs accumulate in the lysosomes, resulting in cellular dysfunction and clinical abnormalities. These are rare conditions, with an estimated total incidence of all types of MPS of approximately 1 in 20.000 live births. Mucopolysaccharidoses are hereditary, progressive disease caused by mutations of genes coding for lysosomal enzymes needed to degrade glycosaminooglycans. Mucopolysaccharidoses are autosomal recessive disorders, with the exception of hunter disease which is x-linked recessive. Their overall frequency is between 3.5/100000 and 4.5/100000. The most common subtype is MPS–III (Sanfilippo), followed by MPS-I (Hurler) and MPS-II (Hunter).