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Abstract
Lysosomes are cytoplasmic organelles that contain a variety of different hydrolases. A genetic deficiency in the enzymatic activity of one of these hydrolases will lead to the accumulation of the material meant for lysosomal degradation. Examples include glycogen in the case of Pompe disease, glycosaminoglycans in the case of the mucopolysaccharidoses, glycoproteins in the cases of the oligosaccharidoses, and sphingolipids in the cases of Niemann-Pick disease types A and B, Gaucher disease, Tay-Sachs disease, Krabbe disease, and metachromatic leukodystrophy. Sometimes, the lysosomal storage can be caused not by the enzymatic deficiency of one of the hydrolases, but by the deficiency of an activator protein, as occurs in the AB variant of GM2 gangliosidosis. Still other times, the accumulated lysosomal material results from failed egress of a small molecule as a consequence of a deficient transporter, as in cystinosis or Salla disease. In the last couple of decades, enzyme replacement therapy has become available for a number of lysosomal storage diseases. Examples include imiglucerase, taliglucerase and velaglucerase for Gaucher disease, laronidase for Hurler disease, idursulfase for Hunter disease, elosulfase for Morquio disease, galsulfase for Maroteaux-Lamy disease, alglucosidase alfa for Pompe disease, and agalsidase alfa and beta for Fabry disease. In addition, substrate reduction therapy has been approved for certain disorders, such as eliglustat for Gaucher disease. The advent of treatment options for some of these disorders has led to newborn screening pilot studies, and ultimately to the addition of Pompe disease and Hurler disease to the Recommended Uniform Screening Panel (RUSP) in 2015 and 2016, respectively.
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Affiliation(s)
- Carlos R. Ferreira
- Division of Genetics and Metabolism, Children’s National Health System, Washington, DC, USA
- George Washington University School of Medicine & Health Sciences, Washington, DC, USA
- Human Biochemical Genetics Section, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - William A. Gahl
- Human Biochemical Genetics Section, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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Maegawa GHB, Stockley T, Tropak M, Banwell B, Blaser S, Kok F, Giugliani R, Mahuran D, Clarke JTR. The natural history of juvenile or subacute GM2 gangliosidosis: 21 new cases and literature review of 134 previously reported. Pediatrics 2006; 118:e1550-62. [PMID: 17015493 PMCID: PMC2910078 DOI: 10.1542/peds.2006-0588] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE Juvenile GM2 gangliosidosis is a group of inherited neurodegenerative diseases caused by deficiency of lysosomal beta-hexosaminidase resulting in GM2 ganglioside accumulation in brain. The purpose of this study was to delineate the natural history of the condition and identify genotype-phenotype correlations that might be helpful in predicting the course of the disease in individual patients. METHODS A cohort of 21 patients with juvenile GM2 gangliosidosis, 15 with the Tay-Sachs variant and 6 with the Sandhoff variant, was studied prospectively in 2 centers. Our experience was compared with previously published reports on 134 patients. Information about clinical features, beta-hexosaminidase enzyme activity, and mutation analysis was collected. RESULTS In our cohort of patients, the mean (+/-SD) age of onset of symptoms was 5.3 +/- 4.1 years, with a mean follow-up time of 8.4 years. The most common symptoms at onset were gait disturbances (66.7%), incoordination (52.4%), speech problems (28.6%), and developmental delay (28.6%). The age of onset of gait disturbances was 7.1 +/- 5.6 years. The mean time for progression to becoming wheelchair-bound was 6.2 +/- 5.5 years. The mean age of onset of speech problems was 7.0 +/- 5.6 years, with a mean time of progression to anarthria of 5.6 +/- 5.3 years. Muscle wasting (10.6 +/- 7.4 years), proximal weakness (11.1 +/- 7.7 years), and incontinence of sphincters (14.6 +/- 9.7 years) appeared later in the course of the disease. Psychiatric disturbances and neuropathy were more prevalent in patients with the Sandhoff variant than in those with the Tay-Sachs variant. However, dysphagia, sphincter incontinence, and sleep problems occurred earlier in those with the Tay-Sachs variant. Cerebellar atrophy was the most common finding on brain MRI (52.9%). The median survival time among the studied and reviewed patients was 14.5 years. The genotype-phenotype correlation revealed that in patients with the Tay-Sachs variant, the presence of R178H and R499H mutations was predictive of an early onset and rapidly progressive course. The presence of either G269S or W474C mutations was associated with a later onset of symptoms along with a more slowly progressive disease course. CONCLUSIONS Juvenile GM2 gangliosidosis is clinically heterogeneous, not only in terms of age of onset and clinical features but also with regard to the course of the disease. In general, the earlier the onset of symptoms, the more rapidly the disease progresses. The Tay-Sachs and Sandhoff variants differed somewhat in the frequency of specific clinical characteristics. Speech deterioration progressed more rapidly than gait abnormalities in both the Tay-Sachs variant and Sandhoff variant groups. Among patients with the Tay-Sachs variant, the HEXA genotype showed a significant correlation with the clinical course.
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Affiliation(s)
- Gustavo H. B. Maegawa
- Division of Clinical and Metabolic Genetics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Tracy Stockley
- Department of Paediatrics, Paediatric Laboratory Medicine, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Michael Tropak
- Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Brenda Banwell
- Division of Neurology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Susan Blaser
- Department of Paediatrics, Diagnostic Imaging, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Fernando Kok
- Centro do Genoma Humano, University of Sao Paulo, Sao Paulo, Brazil
| | - Roberto Giugliani
- Medical Genetics Service, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil
| | - Don Mahuran
- Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Joe T. R. Clarke
- Division of Clinical and Metabolic Genetics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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Lowe JP, Stuckey DJ, Awan FR, Jeyakumar M, Neville DCA, Platt FM, Griffin JL, Styles P, Blamire AM, Sibson NR. MRS reveals additional hexose N-acetyl resonances in the brain of a mouse model for Sandhoff disease. NMR IN BIOMEDICINE 2005; 18:517-26. [PMID: 16206131 DOI: 10.1002/nbm.984] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Sandhoff disease, one of several related lysosomal storage disorders, results from the build up of N-acetyl-containing glycosphingolipids in the brain and is caused by mutations in the genes encoding the hexosaminidase beta-subunit. Affected individuals undergo progressive neurodegeneration in response to the glycosphingolipid storage. (1)H magnetic resonance spectra of perchloric acid extracts of Sandhoff mouse brain exhibited several resonances ca 2.07 ppm that were not present in the corresponding spectra from extracts of wild-type mouse brain. High-performance liquid chromatography and mass spectrometry of the Sandhoff extracts post-MRS identified the presence of N-acetylhexosamine-containing oligosaccharides, which are the likely cause of the additional MRS resonances. MRS of intact brain tissue with magic angle spinning also showed additional resonances at ca 2.07 ppm in the Sandhoff case. These resonances appeared to increase with disease progression and probably arise, for the most part, from the stored glycosphingolipids, which are absent in the aqueous extracts. Hence in vivo MRS may be a useful tool for detecting early-stage Sandhoff disease and response to treatment.
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Affiliation(s)
- J P Lowe
- Experimental Neuroimaging Group, University Laboratory of Physiology, University of Oxford, Parks Road, Oxford, UK
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Hendriksz CJ, Corry PC, Wraith JE, Besley GTN, Cooper A, Ferrie CD. Juvenile Sandhoff disease--nine new cases and a review of the literature. J Inherit Metab Dis 2004; 27:241-9. [PMID: 15159655 DOI: 10.1023/b:boli.0000028777.38551.5a] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Juvenile Sandhoff disease (McKusick 268800) is a rare lysosomal storage disorder with only 12 cases recorded in the literature. This condition is also referred to as the subacute form of hexosaminidase deficiency. We describe 9 new cases of Pakistani origin and compare these with the other published cases. Ataxia and speech abnormalities were the commonest presentation. Constipation and urinary incontinence were frequent and may be due to autonomic neuropathy. Cherry-red spot was not noted in any of our cases. Increased lower limb reflexes were the commonest physical finding. Significant delay in diagnosis may be due to the nonspecific presentation of this condition. Diagnosis was on the basis of hexosaminidase deficiency. Residual enzyme activity did not correlate with the clinical picture. Emerging therapies make early diagnosis of this disorder important.
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Affiliation(s)
- C J Hendriksz
- Willink Biochemical Genetics Unit, Royal Manchester Children's Hospital, Pendlebury, Manchester, UK.
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