Open field locomotor activity and anxiety-related behaviors in mucopolysaccharidosis type IIIA mice

Mucopolysaccharidosis (MPS) IIIA, or Sanfilippo syndrome, is a lysosomal storage disorder characterized by severe and progressive neuropathology. Following an asymptomatic period, patients may present with sleep disturbances, cognitive decline, aggressive tendencies and hyperactivity. A naturally-occurring mouse model of MPS IIIA also exhibits many of these behavioral features and has been recently back-crossed onto a C57BL/6 genetic background. To more thoroughly characterize the behavioral phenotype of congenic MPS IIIA mice, we assessed exploratory activity and unconditioned anxiety-related behavior in the elevated plus maze (EPM) and open field locomotor activity. Although MPS IIIA male mice were less active in the EPM at 18 and 20 weeks of age, they were more likely to explore the open arms than their normal counter-parts suggesting reduced anxiety. Repeated EPM testing reduced exploration of the open arms in MPS IIIA mice. In the open field test, significant reductions in activity were evident in na?ve-tested male MPS IIIA mice from 10 weeks of age. Female normal and MPS IIIA mice displayed similar exploratory activity in the open field test. These differences in anxiety and locomotor activity will allow us to evaluate the efficacy of therapeutic regimes for MPS IIIA as a forerunner to developing safe and effective therapies for Sanfilippo patients.     

Allogeneic stem cell transplantation does not improve neurological deficits in mucopolysaccharidosis type IIIA mice

Mucopolysaccharidosis type IIIA (MPS IIIA) is a neurodegenerative metabolic disorder caused by mutations in the N-sulfoglucosamine sulfohydrolase gene with resultant accumulation of partially degraded heparan sulfate (HS). Whilst allogeneic bone marrow transplantation (BMT) is indicated for several lysosomal storage disorders featuring neurodegeneration, its use in MPS III is highly controversial. Published evidence suggests that BMT does not improve cognitive function in MPS III patients. Despite this, patients continue to be transplanted in some centers. We therefore sought to determine the clinical effectiveness of BMT in a murine model of MPS IIIA. Pre-symptomatic young adult mice pre-conditioned with total body irradiation generated complete and stable donor-type chimerism. Whilst HS-derived disaccharides were reduced by up to 27% in the brain parenchyma, this was insufficient to decrease secondary cholesterol and GM3 ganglioside storage or permit clinical improvement. These results suggest that BMT is ineffective in its unmodified form and should not be considered as a treatment for MPS IIIA children.     

Characterization of a C57BL/6 congenic mouse strain of mucopolysaccharidosis type IIIA

The original mucopolysaccharidosis type IIIA (MPS IIIA) mice were identified in a mixed background with contributions from four different strains. To ensure long-term stability and genetic homogeneity of this lysosomal storage disease (LSD) model, the aim of this study was to develop and characterize a C57BL/6 congenic strain. The B6.Cg-Sgsh(mps3a) strain compares favorably with the original mixed donor strain, exhibiting low liver sulfamidase activity and significant brain heparan sulfate-derived disaccharide elevation from birth. A rapid increase in brain disaccharide levels occurred after birth, with a plateau reached by 13 weeks of age at 110x the levels observed in brains of age-matched unaffected mice. Typical lysosomal inclusions were observed in cerebral cortical and cerebellar neurons and in liver hepatocytes and Kupffer cells. Ubiquitin-positive spheroids and GM(2)-ganglioside were also detected in brain. Using the Morris water maze in male mice, impaired memory and spatial learning was evident at 20 weeks of age in B6.Cg-Sgsh(mps3a) MPS IIIA mice. Other behavioral changes include motor, cognitive and sensory deficits, and aggression. Male B6.Cg-Sgsh(mps3a) MPS IIIA mice exhibited more behavioral abnormalities than B6.Cg-Sgsh(mps3a) MPS IIIA females, as observed previously in the original mixed background strain. Affected mice generally survive to 9 to 12 months of age, before death or euthanasia for humane reasons. Overall, minor differences were apparent between the new congenic and previously described mixed MPS IIIA strains. Availability of an in-bred strain will ensure more reproducible experimental outcomes thereby assisting in our goal of developing effective therapies for LSD with central nervous system disease.     

Hyperactivity and behavioral disorders in Sanfilippo A (mucopolysaccharidosis type IIIA)--case report and review of the literature

Sanfilippo syndrome is one of mucopolysaccharidoses. The main symptom of this syndrome is regression of psychomotor development and neurological signs which occur between 2 and 6 years old. Unlike other mucopolysaccharidoses body dysmorfic features are relatively rare. Course of disease is progressive, most of the patients die before 20. The diagnosis is often difficult. In our opinion in each case presenting psychomotor regression of unknown origin metabolic disease should be excluded (e.g. urine analysis for mucopolysaccharides should be indicated). A 6 year old boy has been under psychiatric and psychological control since he was 3 due to psychomotor retardation, hyperactivity, autistic features, and behavioural disorder. In paediatric examination thickened facial features, coarse hair, knock-knees, short neck were noted. Genetic consultation set up the diagnosis of mucopolysaccharidosis type IIIA (Sanfilippo A disease).     

Cervical myelopathy in mucopolysaccharidosis type IV

We describe our experience with 8 Italian patients having mucopolysaccharidosis type IV, diagnosed between 1 and 10 years of life, who presented odontoid hypoplasia causing cervical myelopathy. We discuss the possibility of cranio-cervical stabilization in order to reduce the neurological complications.     

Neuropathology of murine mucopolysaccharidosis type VII

We describe the neuropathology in mucopolysaccharidosis type VII (MPS VII) mice with a recessively inherited deficiency of the lysosomal enzyme β-glucuronidase. Affected animals have a shortened life span, are dysmorphic, dwarfed and have clinical evidence of behavioral and memory deficiencies. Widespread lysosomal distention with glycosaminoglycan accumulation affects most viscera. In the central nervous system there is progressive accumulation of lysosomal storage in neurons, glia and mesenchymal tissue. The morphological character and the amount of lysosomal storage varies among neuronal groups. In the hippocampus, regional variation in the abundance of lysosomal storage in the MPS VII mice correlates with regional variation in the amount of β-glucuronidase activity in normal mice. The MPS VII mouse provides a well-defined genetic system for the analysis of the neuropathology of MPS VII and is an attractive model on which to test the effects of potential therapies for lysosomal storage disease on the central nervous system. Received: 1 February 1996 / Revised, accepted: 19 April 1996     

Alterations in neuron morphology in mucopolysaccharidosis type I

Summary Morphological changes in neurons with inborn defects of the lysosomal hydrolase, -l-iduronidase, and with concomitant storage of glycosaminoglycans, were evaluated by Golgi staining in two animal models and compared to a similar study of a child with the same disease. Cortical pyramidal neurons in feline mucopolysaccharidosis type I often displayed axon hillock enlargements (meganeurites) and/or ectopic, secondary neuritic processes sprouting from this same region of the cell. The latter structures were prominent and often appeared longer than similar neurites reported in other neuronal storage discases. Although most meganeurites were aspiny, a few were observed which possessed spine-like processes or neurites. Other than these morphological changes in cortical pyramidal neurons, few other cell types displayed abnormalities demonstrable by Golgi impregnation. In the canine model of this disorder, abnormal Golgi-impregnated cortical neurons resembled more closely those seen in human mucopolysaccharidosis. That is, they possessed meganeurites which typically were aspiny in appearance. Ectopic neurite growth was not observed on any Golgi-impregnated neurons in the cases of canine or human mucopolysaccharidosis used in this study. The latter finding given the advanced ages of these cases, is consistent with the view that ectopic neuritogenesis seen in neuronal storage diseases may be subject to a developmental window, albeit one open well beyond the period of early postnatal maturation.Supported by the NIH (NS-18804, SUW; DK-25759, MEH; AM-32126, RMS)     

Homozygosity and severity of phenotypic presentation in a CADASIL family

Most of causative mutations of the cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) are missense point mutations either creating or deleting one cysteine residue, inherited in a heterozygous state. Only few homozygous patients are reported to date and some of them showed phenotypic peculiarities. We here describe a CADASIL family in which a member showed homozygous mutation and compare its clinical profile with five subjects throughout three generation of the pedigree, carrying the same mutation in heterozygosity. The index patient was a 44-year-old Italian man, born from consanguineous parents (first cousins). Symptoms started at 23 years and progressing with recurrent ischemic stroke episode. Diffuse leukoencephalopathy and a severe cognitive impairment were evident, GOMs were detected in skin specimens and a homozygous p.Cys183Ser mutation of the NOTCH3 gene was found. Among the other five heterozygous relatives for the same mutation, both parents developed stroke in advanced age and all the others were clinically asymptomatic. We discuss these findings in relationship to previous data from the literature in CADASIL and in other dominant neurological disorders.     

Myelopathy in mucopolysaccharidosis type II (Hunter syndrome)

A 24-Year-old man with Hunter syndrome had spastic quadriparesis due to impingement of thickened meninges upon the cervical spinal cord. Tracheal narrowing due to submucosal deposits (presumably mucopolysaccharide) produced serious ventilatory complications during induction of anesthesia and necessitated tracheostomy before surgical decompression of the spinal cord could be attempted. Recognition of compressive myelopathy and tracheal compromise as late complications of Hunter syndrome may promote early therapy and prevent respiratory catastrophe.     

New insights in mucopolysaccharidosis type VI: Neurological perspective

Objective: Mucopolysaccharidosis type VI is a rare autosomal recessive storage disorder, caused by deficiency of arylsulfatase B. Data on neurological involvement in mucopolysaccharidosis type VI patients under enzyme-replacement therapy are limited. This study explores the neurological and magnetic resonance imaging findings in a sample of mucopolysaccharidosis type VI patients receiving enzyme-replacement therapy. Methods: We performed a cross-sectional study including six patients with biochemical confirmation of mucopolysaccharidosis type VI and at least 105 consecutive weeks (two years) receiving intravenous enzyme-replacement therapy. The protocol included a comprehensive clinical examination, brain and spinal cord magnetic resonance imaging for all subjects. Results: Overall, cognition was spared, while we found presence of hearing impairment, increasing in deep tendon reflexes and deep sensation reduction in three patients. In addition to the classical abnormalities related to other types of mucopolysaccharidosis, imaging studies demonstrated morphological changes in anatomy of middle cranial fossa and sella shape. Even in asymptomatic or mild compromised patients, spinal cord compression was found. In four patients we noticed atlantoaxial joint subluxation and three had cervical spinal stenosis. Degenerative processes involving vertebral column, including discal protrusion and axis abnormalities, were present in all patients. Conclusions: Neuroaxis involvement was a universal finding and neurological examination might not predict the severity of the disease in course. Image studies should not be performed according exclusively clinical parameters for these patients, once we have demonstrated that neurological involvement may be silent in these patients.     

Skeletal muscle involvement in mucopolysaccharidosis type IIA: severe type of Hunter syndrome

A patient with mucopolysaccharidosis type IIA (MPS IIA) and progressive gait disturbance is described. The histopathology of biopsied muscle was studied; Dorling's method revealed muscle fibers and interstitial cells containing metachromatic granules which suggested the storage of sulfated acidic glycosaminoglycans. Electron microscopy demonstrated that the membrane-bound vacuoles were present in muscle fibers, subsarcolemmal area, vascular endothelial cells, satellite cells, and endomysial fibroblasts. Besides clinical features, this ultrastructural pathology in MPS IIA muscles of MPS IIA was more severe than MPS IIB muscles. The accumulation of glycosaminoglycans in muscle tissue may be an additional factor contributing to gradual motor impairment of patients with MPS IIA.     

Two cases of mucopolysaccharidosis type III (Sanfilippo)

Summary Anatomopathological studies of one case of Sanfilippo disease types A and C, respectively, are presented. The storage phenomenon is very severe in the central as well as in the peripheral nervous system of both patients. Light microscopy does not show significant differences between the two cases. Electron microscopy of the nervous system reveals in both cases the presence of variable amounts of zebra bodies and of membrano-granulo-vacuolar inclusions. The presence of larger amounts of zebra bodies in the type A case and of larger quantities of membrano-granulo-vacuolar inclusions in the type C case constitute probably a non-distinctive feature between the two types. Light and electron microscopic studies of visceral organs do not disclose significant differences either. It is concluded that no major morphological differences between Sanfilippo disease types A and C can be observed.     

Genetic background determines phenotypic severity of the Plp rumpshaker mutation

The rumpshaker mutation of the proteolipid protein (Plp) gene causes dysmyelination in man and mouse. We show that the phenotype in the mouse depends critically on the genetic background in which the mutation is expressed. On the C3H background there is normal longevity whereas changing to a C57BL/6 strain results in seizures and death at around postnatal day 30. The more severe phenotype is associated with less myelin and reduced levels of major myelin proteins. There are also more apoptotic cells, including oligodendrocytes, increased numbers of proliferating cells, increased numbers of NG2+ oligodendrocyte progenitors and increased microglia compared to the milder phenotype. The number of mature oligodendrocytes is similar to wild-type in both strains of mutant, however, suggesting that increased oligodendrocyte death is matched by increased generation from progenitors. The dichotomy of phenotype probably reflects the influence of modifying loci. The localization of these putative modifying genes and their mode of action remain to be determined.     

Pathologic findings in mucopolysaccharidosis type IIIB (Sanfilippo's sydnrome B)

The pathologic changes in a rare case of mucopolysaccharidosis (MPS) type IIIB or Sanfilippo's syndrome B (absence of alpha-N-acetylglucosaminidase) are presented, along with the biochemical findings. Comparisons were made with other reported cases of MPS III subtypes and related storage disorders in terms of clinical, light microscopic, electron microscopic, and chemical findings, and a correlation of the ultrastructural changes made with the severe neurological dysfunction noted in this disorder. At present, MPS III subtypes cannot be separated from one another by morphological means because the same expression and distribution of lesions may be encountered among differing subtypes.     

Cervical decompression in mild mucopolysaccharidosis type II (Hunter syndrome)

Three cases of mild mucopolysaccharidosis type II (Hunter syndrome) who presented with cervical cord compression are reported, with emphasis on their clinical presentations and surgical management. Received: 19 August 1996