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Background: The variants of neuronopathic Gaucher disease may be viewed as a clinical phenotypic continuum divided into acute and chronic forms. The chronic neuronopathic form of Gaucher disease is characterized by a later onset of neurological symptoms and protracted neurological and visceral involvement. The first-choice treatment for nonneuronopathic Gaucher disease is enzyme replacement therapy with recombinant analogues of the deficient human enzyme glucocerebrosidase. Enzyme replacement therapy has been shown to improve hematological and bone manifestations associated with Gaucher disease, but, as with most proteins, recombinant enzymes cannot cross the blood-brain barrier, which prevents effects on neurological manifestations. Substrate reduction therapy with miglustat (N-butyldeoxynojirimycin) inhibits glucosylceramide synthase, which catalyzes the first step in glycosphingolipid synthesis. Because miglustat can cross the blood-brain barrier, it has been suggested that, combined with enzyme replacement therapy, it might be effective in treating neurological symptoms in patients with neuronopathic Gaucher disease.Case Presentation: We report observed effects of combined enzyme replacement therapy and substrate reduction therapy in a 7-year-old Caucasian boy with neuronopathic Gaucher disease who was homozygous for L444P mutations. He had received enzyme replacement therapy from the age of 18 months, and concomitant miglustat treatment was commenced, with dosing according to body surface area uptitrated over 1 month with dietary modifications when he reached the age of 30 months. He experienced mild diarrhea after commencing miglustat therapy, which decreased in frequency/severity over time. His splenomegaly was reduced, and his hematological values and plasma angiotensin-converting enzyme activity normalized. Plasma chitotriosidase also showed substantial and sustained decreases. After 5 years of combination therapy, the patient showed no signs of neurological impairment.Conclusions: This case supports the concept that oral miglustat in combination with intravenous enzyme replacement therapy may be beneficial in preventing neurological signs in patients with chronic neuronopathic Gaucher disease. The importance of dietary modifications has also been confirmed. Further follow-up studies are needed to better define the therapeutic effect of combined treatment in this Gaucher disease subtype. [ABSTRACT FROM AUTHOR]

Cobalamin C (Cbl-C) defects are inherited autosomal recessive disorders of vitamin B12 (or cyanocobalamin [CNCbl]) metabolism. These defects are caused by mutations in the methylmalonic aciduria and homocystinuria Cbl-C type (MMACHC; MIM # 609831) gene located on chromosome 1p34.1, which catalyzes the reductive decyanation of CNCbl, thus impairing the biosynthesis of 5'-deoxyadenosylcobalamin, adenosylcobalamin, and methylcobalamin. This impairment results in methylmalonic acidemia [MMA; MIM # 277400] combined with hyperhomocysteinemia and hypomethioninemia. Clinically, Cbl-C defects are characterized by a constellation of systemic signs and symptoms, including neurological, cognitive, psychiatric, and thromboembolic events. Retinal phenotypes, including maculopathy, pigmentary retinopathy, and optic atrophy, are common in the early-onset form of the disease, but are rare in its adult-onset counterpart. Administration of hydroxocobalamin (OHCbl), betaine, and folinic acid represents main therapeutic approaches. No proven efficacy has been demonstrated for carnitine and dietary protein restrictions. Although early introduction of OHCbl is crucial, no standardized protocols regarding dose adjustment exist. Despite these measures, the long-term outcome is unsatisfactory especially in patients with early onset, who experience frequent progression of their neurological and ocular impairment. The unfavorable outcome suggests that a better understanding of the pathophysiology of the disease is needed to improve treatment protocols and to develop new therapeutic approaches. [ABSTRACT FROM AUTHOR]

The neuronal ceroid lipofuscinoses (NCLs) are a heterogeneous group of inherited, progressive neurodegenerative diseases. Manifestations may begin between the neonatal period and young adulthood, depending on the various subtypes. The different phenotypes are similar and include visual loss, seizures, loss of motor and cognitive function, and early death. At autopsy, there is massive neuronal loss with characteristic storage in the remaining neurons. Neurons appear to die because of increased rates of apoptosis and altered autophagy as occurs in lysosomal storage diseases. A total of 13 neuronal ceroid lipofuscinoses (CLN) genetic forms have been identified so far (CLN type 1-14). In the present review, we propose a classification scheme of the major forms and report the case of a familial recurrence of NCL type 10, with a mutation in the CLN10 gene coding for the cathepsin D protein. [ABSTRACT FROM AUTHOR]

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]

Tetrahydrobiopterin (BH4) is a natural and essential cofactor for the enzymatic hydroxylation of phenylalanine (Phe) and tyrosine (Tyr), and for two tryptophan hydroxylases, three nitric oxide synthases, and glyceryl-ether monooxygenase. Five separate genetic conditions affecting BH4 synthesis or recycling have been identified so far, including deficiency in (1) 6- pyruvoyltetrahydropterin synthase; (2) dihydropteridine reductase; (3) GTP cyclohydrolase I; (4) sepiapterin reductase; and (5) pterin-4α-carbinolamine dehydratase. These disorders cause hyperphenylalaninemia and impaired synthesis of serotonin and dopamine since tyrosine hydroxylase and neuronal tryptophan hydroxylase require BH4 and serotonin/dopamine products (5-hydroxytryptophan and L-dopa). All these five genetic conditions can be identified by newborn screening procedures due to elevated blood levels of Phe (with the sole exception of sepiapterin reductase deficiency). BH4 loading tests and measurement of neurotransmitter metabolites, pterins, and folates in cerebrospinal fluid can add further important information on disease severity. Untreated patients develop a complex neurological phenotype, which includes Parkinson-like features, brain degeneration, and early death. The gold standard treatment of severe disorders of BH4 metabolism is based on replacement therapy with BH4, 5-hydroxytryptophan, L-dopa, and carbidopa, with the addition, in certain cases, of folinic acid supplements and pramipexole. Dopamine agonists can improve L-dopa therapy, making treatment easier, relieving symptoms, stabilizing clinical course, and possibly ameliorating long-term outcomes. The outcome of patients with disorders of biopterin synthesis can be favorable, with either normal or near-normal cognition, and with some residual neurological symptoms usually manifesting diurnal variation, that is, worst when patients become tired or when the dosage or interval for medications is inadequate. [ABSTRACT FROM AUTHOR]