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Gaucher disease (GD) has been classically divided into three phenotypes primarily according to the absence (type 1 GD or nonneuronopathic GD) or presence and severity (types 2 and 3 GD or neuronopathic GD) of neurological involvement. Despite such distinction, neurological manifestations have been recorded also in patients with type 1 GD: in this latter form, however, such manifestations are different and, in the majority of cases, of much less severity than those associated with types 2 and 3 GD. Significant advances in therapy have been achieved, primarily after the advent of enzyme replacement therapy (ERT). As it occurs in patients with type 1 GD, ERT is able to reverse systemic and extraneurological manifestations of type 3 GD, although evidence suggests that ERT is not able to prevent the progression of neurological involvement in the long term. Thus, it is necessary to better understand the pathophysiological mechanism underlying neurological involvement in GD patients, allowing the development of new therapeutic approaches capable of improving central nervous system manifestations in GD. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Lysosomal storage disorders (LSDs) are a heterogeneous group of inborn errors of metabolism caused by inherited deficiencies of any of the lysosomal functions, leading to the accumulation of undegraded substrates in multiple tissues and organs. Two-third of LSDs involves the central nervous system, thus representing the most common cause of pediatric neurodegenerative diseases. Substantial progress has been made in our understanding of the pathophysiology of LSDs, leading to newly targeted therapeutic options. Enzyme replacement therapy (ERT) is currently available for seven LSDs including Gaucher disease, Fabry disease, Pompe disease, and mucopolysaccharidosis (MPS) I (Hurler disease), II (Hunter disease), IV A (Morquio A), and VI (Maroteaux-Lamy disease). ERT reduces lysosomal storage, thus slowing or sometimes avoiding progressive visceral damage altogether. However, ERT is unable to cross the blood-brain barrier (BBB), thus lacking efficacy on neurological manifestations. In patients with MPS I (Hurler disease) under 2 years of age and in selected patients with other LSD, hematopoietic stem cell transplantation is indicated. To bypass the BBB, other approaches, using small molecules are currently being tested and include substrate reduction therapy, which decreases the amount of substrate (currently available for type 1 Gaucher disease and for Niemann-Pick type C disease) and pharmacological chaperones, which enhance the residual activity of the mutant enzyme. [ABSTRACT FROM AUTHOR]