The Different Forms of Mucopolysaccharidosis with Neurological Involvement: A Case-Based Review

Abstract

The mucopolysaccharidoses (MPSs) are a group of rare lysosomal storage disorders caused by deficiency of enzymes catalyzing the stepwise degradation of glycosaminoglycans dermatan sulfate, heparan sulfate, keratan sulfate, chondroitin sulfate, and hyaluronic acid. There are seven groups of MPS, which are MPS-I (MPS-I-H or Hurler syndrome; MPS-I-S or Scheie syndrome; and MPS-I-HS or Hurler–Scheie syndrome), MPS-II (Hunter syndrome), MPS-III (Sanfilippo syndrome types A to D), MPS-IV (Morquio syndrome types A and B), MPS-VI (Maroteaux–Lamy syndrome), MPS-VII (Sly syndrome), and MPS-IX (Natowicz syndrome). All are inherited as autosomal recessive diseases, with the exception of Hunter syndrome, which follows an X-linked recessive inheritance pattern. The MPSs affect multiple organ systems (including bone, heart, and visceral organs), leading to organ failure. Involvement of central nervous system occurs only in the forms with heparan sulfate accumulation, that is, MPS-I, MPS-II, MPS-III, and MPS-VII. Therapy is available for MPS-I, MPS-II, MPS-IV, and MPS-VI. This review provides a case-based overview of the different forms of MPS with neurological involvement.