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Alonso-Pérez J, Casasús A, Gimenez-Muñoz Á, Duff J, Rojas-Garcia R, Illa I, Straub V, Töpf A, Díaz-Manera J. Late onset Sandhoff disease presenting with lower motor neuron disease and stuttering. Neuromuscul Disord 2021; 31:769-772. [PMID: 34210542 DOI: 10.1016/j.nmd.2021.04.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 10/21/2022]
Abstract
Defects in the HEXB gene which encodes the β-subunit of β-hexosaminidase A and B enzymes, cause a GM2 gangliosidosis, also known as Sandhoff disease, which is a rare lysosomal storage disorder. The most common form of the disease lead to quickly progressing mental and motor decline in infancy; however there are other less severe forms with later onset that can also involve lower motor neurons. The diagnosis of this disease is based on low serum β-hexosaminidases A and B levels and confirmed using genetic test. We report two siblings with compound heterozygous HEXB mutations whose phenotype was extremely mild consisting in stuttering in both cases associated to mild proximal weakness in one of the cases, broadening the clinical spectrum of late onset Sandhoff disease.
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Affiliation(s)
- Jorge Alonso-Pérez
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Ana Casasús
- The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle Upon Tyne, United Kingdom; Neuromuscular Research Unit, IIS La Fe, Valencia, Spain
| | | | - Jennifer Duff
- The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle Upon Tyne, United Kingdom
| | - Ricard Rojas-Garcia
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Spain
| | - Isabel Illa
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Spain
| | - Volker Straub
- The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle Upon Tyne, United Kingdom
| | - Ana Töpf
- The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle Upon Tyne, United Kingdom
| | - Jordi Díaz-Manera
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain; The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle Upon Tyne, United Kingdom; Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Spain.
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Masingue M, Dufour L, Lenglet T, Saleille L, Goizet C, Ayrignac X, Ory-Magne F, Barth M, Lamari F, Mandia D, Caillaud C, Nadjar Y. Natural History of Adult Patients with GM2 Gangliosidosis. Ann Neurol 2020; 87:609-617. [PMID: 31995250 DOI: 10.1002/ana.25689] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 01/23/2020] [Accepted: 01/23/2020] [Indexed: 11/09/2022]
Abstract
OBJECTIVE GM2 gangliosidoses are lysosomal diseases due to biallelic mutations in the HEXA (Tay-Sachs disease [TS]) or HEXB (Sandhoff disease [SD]) genes, with subsequent low hexosaminidase(s) activity. Most patients have childhood onset, but some experience the first symptoms during adolescence/adulthood. This study aims to clarify the natural history of adult patients with GM2 gangliosidosis. METHODS We retrospectively described 12 patients from a French cohort and 45 patients from the literature. RESULTS We observed 4 typical presentations: (1) lower motoneuron disorder responsible for proximal lower limb weakness that subsequently expanded to the upper limbs, (2) cerebellar ataxia, (3) psychosis and/or severe mood disorder (only in the TS patients), and (4) a complex phenotype mixing the above 3 manifestations. The psoas was the first and most affected muscle in the lower limbs, whereas the triceps and interosseous were predominantly involved in the upper limbs. A longitudinal study of compound motor action potentials showed a progressive decrease in all nerves, with different kinetics. Sensory potentials were sometimes abnormally low, mainly in the SD patients. The main brain magnetic resonance imaging feature was cerebellar atrophy, even in patients without cerebellar symptoms. The prognosis was mainly related to gait disorder, as we showed that beyond 20 years of disease evolution, half of the patients were wheelchair users. INTERPRETATION Improved knowledge of GM2 gangliosidosis in adults will help clinicians achieve correct diagnoses and better inform patients on the evolution and prognosis. It may also contribute to defining proper outcome measures when testing emerging therapies. ANN NEUROL 2020;87:609-617.
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Affiliation(s)
- Marion Masingue
- Reference Center for Neuromuscular Disorders Nord/Est/Île-de-France, Institute of Myology, Pitié-Salpêtrière University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris
| | - Louis Dufour
- Department of Neurology, Reference Center for Lysosomal Diseases, Neuro-Genetic and Metabolism Unit, Pitié-Salpêtrière University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris
| | - Timothée Lenglet
- Department of Neurophysiology, Pitié-Salpêtrière University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris.,Department of Neurology, Reference Center for ALS Rare Disease, Pitié-Salpêtrière University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris
| | - Lisa Saleille
- Department of Neurology, Reference Center for Lysosomal Diseases, Neuro-Genetic and Metabolism Unit, Pitié-Salpêtrière University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris
| | - Cyril Goizet
- Reference Center for Rare "Neurogenetic" Diseases, Department of Medical Genetics, Pellegrin Hospital, Bordeaux University Hospital Center, Bordeaux.,Rare Diseases Laboratory: Genetics and Metabolism, National Institute of Health and Medical Research U1211, Bordeaux University, Bordeaux
| | - Xavier Ayrignac
- Department of Neurology, Reference Center for Adult Leukodystrophies, Montpellier University Hospital Center, National Institute of Health and Medical Research, University of Montpellier, Montpellier
| | - Fabienne Ory-Magne
- Department of Neurology, University Hospital, National Institute of Health and Medical Research, Brain Imaging and Neurological Disabilities, Mixed Unit of Research 1214, Toulouse
| | - Magali Barth
- Department of Genetics, Reference Center for Neurogenetic Diseases, University Hospital Angers, Angers
| | - Foudil Lamari
- Biochemistry of Neurometabolic Diseases Functional Units, Department of Metabolic Biochemistry, Pitié-Salpêtrière University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris
| | - Daniele Mandia
- Department of Neurology, Reference Center for Lysosomal Diseases, Neuro-Genetic and Metabolism Unit, Pitié-Salpêtrière University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris
| | - Catherine Caillaud
- Biochemical, Metabolomic, and Proteomic Department, Necker University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris.,National Institute of Health and Medical Research U1151, Necker University Hospital Group, Paris Descartes University, Sorbonne Paris Cité, Paris, France
| | - Yann Nadjar
- Department of Neurology, Reference Center for Lysosomal Diseases, Neuro-Genetic and Metabolism Unit, Pitié-Salpêtrière University Hospital Group (Assistance publique Hôpitaux de Paris (AP-HP)), Paris
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3
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Identification of mutations in HEXA and HEXB in Sandhoff and Tay-Sachs diseases: a new large deletion caused by Alu elements in HEXA. Hum Genome Var 2018; 5:18003. [PMID: 31428437 PMCID: PMC6694291 DOI: 10.1038/hgv.2018.3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/21/2017] [Accepted: 12/21/2017] [Indexed: 12/12/2022] Open
Abstract
GM2 gangliosides are a group of lysosomal lipid storage disorders that are due to mutations in HEXA, HEXB and GM2A. In our study, 10 patients with these diseases were enrolled, and Sanger sequencing was performed for the HEXA and HEXB genes. The results revealed one known splice site mutation (c.346+1G>A, IVS2+1G>A) and three novel mutations (a large deletion involving exons 6–10; one nucleotide deletion, c.622delG [p.D208Ifsx15]; and a missense mutation, c.919G>A [p.E307K]) in HEXA. In HEXB, one known mutation (c.1597C>T [p.R533C]) and one variant of uncertain significance (c.619A>G [p.I207V]) were identified. Five patients had c.1597C>T in HEXB, indicating a common mutation in south Iran. In this study, a unique large deletion in HEXA was identified as a homozygous state. To predict the cause of the large deletion in HEXA, RepeatMasker was used to investigate the Alu elements. In addition, to identify the breakpoint of this deletion, PCR was performed around these elements. Using Repeat masker, different Alu elements were identified across HEXA, mainly in intron 5 and intron 10 adjacent to the deleted exons. PCR around the Alu elements and Sanger sequencing revealed the start point of a large deletion in AluSz6 in the intron 6 and the end of its breakpoint 73 nucleotides downstream of AluJo in intron 10. Our study showed that HEXA is an Alu-rich gene that predisposes individuals to disease-associated large deletions due to these elements.
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Zhang W, Zeng H, Huang Y, Xie T, Zheng J, Zhao X, Sheng H, Liu H, Liu L. Clinical,biochemical and molecular analysis of five Chinese patients with Sandhoff disease. Metab Brain Dis 2016; 31:861-7. [PMID: 27021291 DOI: 10.1007/s11011-016-9819-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/02/2016] [Indexed: 11/25/2022]
Abstract
Sandhoff disease (SD) is a rare autosomal recessive lysosomal storage disorder of sphingolipid metabolism resulting from the deficiency of β-hexosaminidase (HEX). Mutations of the HEXB gene cause Sandhoff disease. In order to improve the diagnosis and expand the knowledge of the disease, we collected and analyzed relevant data of clinical diagnosis, biochemical investigation, and molecular mutational analysis in five Chinese patients with SD. The patients presented with heterogenous symptoms of neurologic deterioration. HEX activity in leukocytes was severely deficient. We identified seven different mutations, including three known mutations: IVS12-26G > A, p.T209I, p.I207V, and four novel mutations: p.P468PfsX62, p.L223P, p.Y463X, p.G549R. We also detected two different heterozygous mutations c.-122delC and c.-126C > T in the promoter which were suspected to be deleterious mutations. We attempted to correlate these mutations with the clinical presentation of the patients. Our study indicates that the mutation p.T209I and p.P468PfsX62 may link to the infantile form of SD. Our study expands the spectrum of genotype of SD in China, provides new insights into the molecular mechanism of SD and helps to the diagnosis and treatment of this disease.
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Affiliation(s)
- Wen Zhang
- Department of Pediatrics, The First Affiliated Hospital, Jinan University, Guangzhou, Guangdong, China
| | - Huasong Zeng
- Department of Immunology and Rheumatology, Guangzhou Women and Children's Medical Center, Guangzhou, Guangdong, China
| | - Yonglan Huang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, Guangzhou, Guangdong, 510623, China.
| | - Ting Xie
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, Guangzhou, Guangdong, 510623, China
| | - Jipeng Zheng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, Guangzhou, Guangdong, 510623, China
| | - Xiaoyuan Zhao
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, Guangzhou, Guangdong, 510623, China
| | - Huiying Sheng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, Guangzhou, Guangdong, 510623, China
| | - Hongsheng Liu
- Department of Radiology, Guangzhou Women and Children's Medical Center, Guangzhou, Guangdong, China
| | - Li Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, Guangzhou, Guangdong, 510623, China.
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Yasui N, Takaoka Y, Nishio H, Nurputra DK, Sekiguchi K, Hamaguchi H, Kowa H, Maeda E, Sugano A, Miura K, Sakaeda T, Kanda F, Toda T. Molecular pathology of Sandhoff disease with p.Arg505Gln in HEXB: application of simulation analysis. J Hum Genet 2013; 58:611-7. [DOI: 10.1038/jhg.2013.68] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 05/15/2013] [Accepted: 05/19/2013] [Indexed: 11/09/2022]
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Yamada K, Takado Y, Kato YS, Yamada Y, Ishiguro H, Wakamatsu N. Characterization of the mutant β-subunit of β-hexosaminidase for dimer formation responsible for the adult form of Sandhoff disease with the motor neuron disease phenotype. J Biochem 2012; 153:111-9. [PMID: 23127958 DOI: 10.1093/jb/mvs131] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The adult form of Sandhoff disease with the motor neuron disease phenotype is a rare neurodegenerative disorder caused by mutations in HEXB encoding the β-subunit of β-hexosaminidase, yet the properties of mutant β-subunits of the disease have not been fully determined. We identified a novel mutation (H235Y) in the β-sheet of the (β/α)₈-barrel domain, in addition to the previously reported P417L mutation that causes aberrant splicing, in a Japanese patient with the motor neuron disease phenotype. Enzyme assays, gel filtration studies and immunoprecipitation studies with HEK293 cells transiently expressing mutant β-subunits demonstrated that the H235Y mutation abolished both α-β and β-β dimer formation without increasing β-hexosaminidase activity, whereas other reported mutant β-subunits (Y456S, P504S or R533H) associated with the motor neuron disease phenotype formed dimers. Structural analysis suggested that the H235Y mutation in the β-sheet of the (β/α)₈-barrel domain changed the conformation of the β-subunit by causing a clash with the E288 side chain. In summary, H235Y is the first mutation in the β-sheet of the (β/α)₈-barrel domain of the β-subunit that abolishes α-β and β-β dimer formation; the presented patient is the second patient to exhibit the motor neuron disease phenotype with P417L and a non-functional allele of HEXB.
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Affiliation(s)
- Kenichiro Yamada
- Department of Genetics, Institute for Developmental Research, Aichi Human Service Center, 713-8 Kamiya-cho, Kasugai, Aichi 480-0392, Japan
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7
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Kodama T, Togawa T, Tsukimura T, Kawashima I, Matsuoka K, Kitakaze K, Tsuji D, Itoh K, Ishida YI, Suzuki M, Suzuki T, Sakuraba H. Lyso-GM2 ganglioside: a possible biomarker of Tay-Sachs disease and Sandhoff disease. PLoS One 2011; 6:e29074. [PMID: 22205997 PMCID: PMC3243693 DOI: 10.1371/journal.pone.0029074] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Accepted: 11/20/2011] [Indexed: 11/18/2022] Open
Abstract
To find a new biomarker of Tay-Sachs disease and Sandhoff disease. The lyso-GM2 ganglioside (lyso-GM2) levels in the brain and plasma in Sandhoff mice were measured by means of high performance liquid chromatography and the effect of a modified hexosaminidase (Hex) B exhibiting Hex A-like activity was examined. Then, the lyso-GM2 concentrations in human plasma samples were determined. The lyso-GM2 levels in the brain and plasma in Sandhoff mice were apparently increased compared with those in wild-type mice, and they decreased on intracerebroventricular administration of the modified Hex B. The lyso-GM2 levels in plasma of patients with Tay-Sachs disease and Sandhoff disease were increased, and the increase in lyso-GM2 was associated with a decrease in Hex A activity. Lyso-GM2 is expected to be a potential biomarker of Tay-Sachs disease and Sandhoff disease.
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Affiliation(s)
- Takashi Kodama
- Department of Analytical Biochemistry, Meiji Pharmaceutical University, Tokyo, Japan
| | - Tadayasu Togawa
- Department of Analytical Biochemistry, Meiji Pharmaceutical University, Tokyo, Japan
| | - Takahiro Tsukimura
- Department of Analytical Biochemistry, Meiji Pharmaceutical University, Tokyo, Japan
| | - Ikuo Kawashima
- Department of Clinical Genetics, Meiji Pharmaceutical University, Tokyo, Japan
- Department of Molecular Medical Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Kazuhiko Matsuoka
- Department of Medicinal Biotechnology, Institute for Medicinal Research, Graduate School of Pharmaceutical Sciences, The University of Tokushima, Tokushima, Japan
| | - Keisuke Kitakaze
- Department of Medicinal Biotechnology, Institute for Medicinal Research, Graduate School of Pharmaceutical Sciences, The University of Tokushima, Tokushima, Japan
| | - Daisuke Tsuji
- Department of Medicinal Biotechnology, Institute for Medicinal Research, Graduate School of Pharmaceutical Sciences, The University of Tokushima, Tokushima, Japan
| | - Kohji Itoh
- Department of Medicinal Biotechnology, Institute for Medicinal Research, Graduate School of Pharmaceutical Sciences, The University of Tokushima, Tokushima, Japan
| | - Yo-ichi Ishida
- Department of Molecular Biochemistry, Meiji Pharmaceutical University, Tokyo, Japan
| | - Minoru Suzuki
- Disease Glycomics Team, Systems Glycobiology Research Group, RIKEN, Saitama, Japan
| | - Toshihiro Suzuki
- Department of Analytical Biochemistry, Meiji Pharmaceutical University, Tokyo, Japan
| | - Hitoshi Sakuraba
- Department of Analytical Biochemistry, Meiji Pharmaceutical University, Tokyo, Japan
- Department of Clinical Genetics, Meiji Pharmaceutical University, Tokyo, Japan
- * E-mail:
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8
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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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Utsumi K, Tsuji A, Kase R, Tanaka A, Tanaka T, Uyama E, Ozawa T, Sakuraba H, Komaba Y, Kawabe M, Iino Y, Katayama Y. Western blotting analysis of the beta-hexosaminidase alpha- and beta-subunits in cultured fibroblasts from cases of various forms of GM2 gangliosidosis. Acta Neurol Scand 2002; 105:427-30. [PMID: 12027830 DOI: 10.1034/j.1600-0404.2002.01097.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES The GM2 gangliosidoses are a group of genetic disorders caused by the accumulation of ganglioside GM2 in neuronal cells. We examined the alpha- and beta-subunits of beta-hexosaminidases by a non-radioisotopes detecting system to evaluate whether it was a useful method for understanding of the pathophysiologies of GM2 gangliosidoses. MATERIALS AND METHODS We investigated the alpha- and beta-subunits of beta-hexosaminidases in cultured fibroblasts from cases of various forms of GM2 gangliosidosis by means of Western blotting and a chemiluminescence detection system. RESULTS In a patient with infantile Tay-Sachs disease [HEXA genotype, Int5-SA(g-1-->t)/Int5-SA(g-1-->t)], the mature alpha-subunit was undetectable. In a patient with infantile Sandhoff disease (HEXB genotype, C534Y/C534Y), the mature beta-subunit was deficient. However, a small amount of the mature beta-subunit was detected in a patient with adult Sandhoff disease (HEXB genotype, R505Q(+I207V)/R505Q(+I207V)), which may have resulted in the residual enzyme activity and mild clinical course. Normal amounts of alpha- and beta-subunits were detected in a patient with GM2 activator deficiency. CONCLUSION This method is easy and sensitive for detecting target proteins, and is useful for clarification of the pathophysiologies of GM2 gangliosidoses.
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Affiliation(s)
- K Utsumi
- The Second Department of Internal Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, Japan. utsumi_kouichi/
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Yoshizawa T, Kohno Y, Nissato S, Shoji S. Compound heterozygosity with two novel mutations in the HEXB gene produces adult Sandhoff disease presenting as a motor neuron disease phenotype. J Neurol Sci 2002; 195:129-38. [PMID: 11897243 DOI: 10.1016/s0022-510x(02)00007-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Little information is available on molecular defects involved in adult Sandhoff disease presenting as motor neuron disease phenotype. We studied enzyme activities of beta-hexosaminidase (Hex) and the HEXB gene encoding the beta-subunit of Hex in a family of the Japanese case. Enzyme assay with 4-methylumbelliferyl-2-acetamido-2-deoxy-beta-D-glucopyranoside revealed a reduction in Hex A and B activity in proband's leukocytes. Although the activity of both in the mother were intermediate between those of controls and the proband, only Hex B reduction determined with heat inactivation was found in the father. Analysis of HEXB gene demonstrated two novel point mutations. The first mutation, IVS2-1G>A, was located at the 3'-splice acceptor site of intron 2 derived from the mother, causing exon 3 skipping. The resultant mRNA encoded a shorter beta-chain, which may not form an active enzyme. The second mutation was a G-to-A transition in exon 13 (c.1598G>A) derived from the father and resulted in arginine-to-histidine substitution at amino acid position 533 (R533H). Expression of R533H mutation in COS-1 cells demonstrated a lack of normal Hex activity, indicating that this mutation is pathological. Compound heterozygosity of these two mutations may trigger the development of adult Sandhoff disease with a motor neuron disease phenotype.
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Affiliation(s)
- Toshihiro Yoshizawa
- Department of Neurology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennodai, 305-8575, Tsukuba, Japan.
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