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Grønbæk-Thygesen M, Hartmann-Petersen R. Cellular and molecular mechanisms of aspartoacylase and its role in Canavan disease. Cell Biosci 2024; 14:45. [PMID: 38582917 PMCID: PMC10998430 DOI: 10.1186/s13578-024-01224-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 03/24/2024] [Indexed: 04/08/2024] Open
Abstract
Canavan disease is an autosomal recessive and lethal neurological disorder, characterized by the spongy degeneration of the white matter in the brain. The disease is caused by a deficiency of the cytosolic aspartoacylase (ASPA) enzyme, which catalyzes the hydrolysis of N-acetyl-aspartate (NAA), an abundant brain metabolite, into aspartate and acetate. On the physiological level, the mechanism of pathogenicity remains somewhat obscure, with multiple, not mutually exclusive, suggested hypotheses. At the molecular level, recent studies have shown that most disease linked ASPA gene variants lead to a structural destabilization and subsequent proteasomal degradation of the ASPA protein variants, and accordingly Canavan disease should in general be considered a protein misfolding disorder. Here, we comprehensively summarize the molecular and cell biology of ASPA, with a particular focus on disease-linked gene variants and the pathophysiology of Canavan disease. We highlight the importance of high-throughput technologies and computational prediction tools for making genotype-phenotype predictions as we await the results of ongoing trials with gene therapy for Canavan disease.
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Affiliation(s)
- Martin Grønbæk-Thygesen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200N, Copenhagen, Denmark.
| | - Rasmus Hartmann-Petersen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200N, Copenhagen, Denmark.
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Thakkar RN, Patel D, Kioutchoukova IP, Al-Bahou R, Reddy P, Foster DT, Lucke-Wold B. Leukodystrophy Imaging: Insights for Diagnostic Dilemmas. Med Sci (Basel) 2024; 12:7. [PMID: 38390857 PMCID: PMC10885080 DOI: 10.3390/medsci12010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/09/2023] [Accepted: 12/13/2023] [Indexed: 02/24/2024] Open
Abstract
Leukodystrophies, a group of rare demyelinating disorders, mainly affect the CNS. Clinical presentation of different types of leukodystrophies can be nonspecific, and thus, imaging techniques like MRI can be used for a more definitive diagnosis. These diseases are characterized as cerebral lesions with characteristic demyelinating patterns which can be used as differentiating tools. In this review, we talk about these MRI study findings for each leukodystrophy, associated genetics, blood work that can help in differentiation, emerging diagnostics, and a follow-up imaging strategy. The leukodystrophies discussed in this paper include X-linked adrenoleukodystrophy, metachromatic leukodystrophy, Krabbe's disease, Pelizaeus-Merzbacher disease, Alexander's disease, Canavan disease, and Aicardi-Goutières Syndrome.
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Affiliation(s)
- Rajvi N. Thakkar
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Drashti Patel
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | | | - Raja Al-Bahou
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Pranith Reddy
- College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, USA
| | - Devon T. Foster
- College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Brandon Lucke-Wold
- Department of Neurosurgery, University of Florida, 1600 SW Archer Rd., Gainesville, FL 32610, USA
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LC–MS/MS determination of N-acetylaspartic acid in dried blood spot for selective screening of Canavan disease. MONATSHEFTE FUR CHEMIE 2019. [DOI: 10.1007/s00706-018-2349-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Jurdáková H, Górová R, Addová G, Behúlová D, Ostrovský I. The state of treatment approach and diagnostics in Canavan disease with focus on the determination of N-acetylasparic acid. CHEMICAL PAPERS 2017. [DOI: 10.1007/s11696-016-0033-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ahmed SS, Gao G. Making the White Matter Matters: Progress in Understanding Canavan's Disease and Therapeutic Interventions Through Eight Decades. JIMD Rep 2015; 19:11-22. [PMID: 25604619 DOI: 10.1007/8904_2014_356] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 08/05/2014] [Accepted: 08/12/2014] [Indexed: 12/24/2022] Open
Abstract
Canavan's disease (CD) is a fatal autosomal recessive pediatric leukodystrophy in which patients show severe neurodegeneration and typically die by the age of 10, though life expectancy in patients can be highly variable. Currently, there is no effective treatment for CD; however, gene therapy seems to be a feasible approach to combat the disease. Being a monogenic defect, the disease provides an excellent model system to develop gene therapy approaches that can be extended to other monogenic leukodystrophies and neurodegenerative diseases. CD results from mutations in a single gene aspartoacylase which hydrolyses N-acetyl aspartic acid (NAA) which accumulates in its absences. Since CD is one of the few diseases that show high NAA levels, it can also be used to study the enigmatic biological role of NAA. The disease was first described in 1931, and this review traces the progress made in the past 8 decades to understand the disease by enumerating current hypotheses and ongoing palliative measures to alleviate patient symptoms in the context of the latest advances in the field.
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Affiliation(s)
- Seemin S Ahmed
- University of Massachusetts Medical School, 368 Plantation Street, ASC6, Worcester, MA, 01605, USA
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Molecular characterisation and prenatal diagnosis of Asparto-acylase deficiency (Canavan disease)--report of two novel and two known mutations from the Indian subcontinent. Indian J Pediatr 2013; 80:26-31. [PMID: 22878930 DOI: 10.1007/s12098-012-0862-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 07/11/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVES To establish a technique for mutation identification and prenatal screening in confirmed cases of Canavan disease. METHOD Mutations in ASPA gene were identified by sequencing. Six exons of ASPA gene were amplified using intronic primers flanking the exons and then sequenced on ABI 3500Dx automated unit. This technique was used to identify mutations in three cases of Canavan disease. Prenatal diagnosis was performed in two families. RESULTS Two reported mutations c.162 C > A (p.Asn54Lys) and c.859 G > A (p.Ala287Thr) were identified in two different cases of Canavan disease. Third case was compound heterozygous for two novel mutations (c.728 T > G, p.Ile243Ser; c.902 T > C, p.Leu301Pro). Prenatal diagnosis was performed in three pregnancies in two families, two affected fetuses and one unaffected fetus were identified. CONCLUSIONS Molecular characterization of Canavan disease helps identify the cause at genetic level, thus confirming diagnosis and enabling identification of carriers in the family. Though enzyme assay and NAA measurement allows diagnosis and prenatal diagnosis of Canavan diasease, molecular methods have the advantage of bringing accuracy in prenatal testing with an earlier result. This is the first case report of mutation studies in Canavan disease from Indian subcontinent.
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Surendran S, Bhatnagar M. Upregulation of N-acetylaspartic acid induces oxidative stress to contribute in disease pathophysiology. Int J Neurosci 2011; 121:305-9. [PMID: 21348802 DOI: 10.3109/00207454.2011.558225] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
N-acetylaspartic acid (NAA) is predominantly present in brain and also present in lower amount in peripheral organs. The role of NAA in pathophysiology is poorly understood. Therefore the review was aimed to understand contribution of NAA in disease process. Amniotic fluid of mothers with Canavan disease (CD) fetus and patients with the disease show increased levels of NAA. Increase of this pathway is also reported in Parkinson's disease and type 2 diabetes. In HIV-related dementia, NAA is affected. Recent studies suggest that upregulation of NAA leads to oxidative stress including upregulation of nitric oxide and reducing potential antioxidants. NAA also leads to physiological abnormalities including walking disorder. These changes suggest that NAA contributes in disease pathophysiology.
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Matalon R, Michals-Matalon K. Spongy Degeneration of the Brain, Canavan Disease: Biochemical and Molecular Findings. ACTA ACUST UNITED AC 2010. [DOI: 10.1080/15513819809168802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Colaianni A, Chandrasekharan S, Cook-Deegan R. Impact of gene patents and licensing practices on access to genetic testing and carrier screening for Tay-Sachs and Canavan disease. Genet Med 2010; 12:S5-S14. [PMID: 20393311 PMCID: PMC3042321 DOI: 10.1097/gim.0b013e3181d5a669] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Genetic testing for Tay-Sachs and Canavan disease is particularly important for Ashkenazi Jews, because both conditions are more frequent in that population. This comparative case study was possible because of different patenting and licensing practices. The role of DNA testing differs between Tay-Sachs and Canavan diseases. The first-line screening test for Tay-Sachs remains an enzyme activity test rather than genotyping. Genotyping is used for preimplantation diagnosis and confirmatory testing. In contrast, DNA-based testing is the basis for Canavan screening and diagnosis. The HEXA gene for Tay-Sachs was cloned at the National Institutes of Health, and the gene was patented but has not been licensed. The ASPA gene for Canavan disease was cloned and patented by Miami Children's Hospital. Miami Children's Hospital did not inform family members and patient groups that had contributed to the gene discovery that it was applying for a patent, and pursued restrictive licensing practices when a patent issued in 1997. This led to intense controversy, litigation, and a sealed, nonpublic 2003 settlement that apparently allowed for nonexclusive licensing. A survey of laboratories revealed a possible price premium for ASPA testing, with per-unit costs higher than for other genetic tests in the Secretary's Advisory Committee on Genetics, Health, and Society case studies. The main conclusion from comparing genetic testing for Tay-Sachs and Canavan diseases, however, is that patenting and licensing conducted without communication with patients and advocates cause mistrust and can lead to controversy and litigation, a negative model to contrast with the positive model of patenting and licensing for genetic testing of cystic fibrosis.
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Affiliation(s)
- Alessandra Colaianni
- Center for Public Genomics, Center for Genome Ethics, Law & Policy, Institute for Genome Sciences & Policy, Duke University, Durham, NC 27708, USA
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Al-Dirbashi OY, Kurdi W, Imtiaz F, Ahmad AM, Al-Sayed M, Tulbah M, Al-Nemer M, Rashed MS. Reliable prenatal diagnosis of Canavan disease by measuringN-acetylaspartate in amniotic fluid using liquid chromatography tandem mass spectrometry. Prenat Diagn 2009; 29:477-80. [DOI: 10.1002/pd.2223] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Surendran S. Upregulation of N-acetylaspartic acid alters inflammation, transcription and contractile associated protein levels in the stomach and smooth muscle contractility. Mol Biol Rep 2007; 36:201-6. [PMID: 17943458 DOI: 10.1007/s11033-007-9167-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Accepted: 10/05/2007] [Indexed: 12/29/2022]
Abstract
N-acetylaspartic acid (NAA) is converted into aspartate and acetate by aspartoacylase. Abnormal levels of the enzyme leads to accumulation of NAA and these changes have been observed in Canavan disease and type 2 diabetes. How upregulation of NAA affect the gastrointestine protein levels and the function is not known. Incubation of rat stomach tissue with NAA 1.5 mM, 1.5 microM and 1.5 nM induced inflammatory agents TNFalpha, p38MAPK, iNOS, PKC, COX2 and ICAM3; transcription factors phospho-NF-kBp65, cjun and cfos; contractile proteins MLCK and phospho MLC; and calcium channel alpha1C and calcium channel, voltage-dependent, beta 3 subunit compared to their respective control. Incubation of circular smooth muscle cells with the above doses of NAA induced contractility compared to the control. These studies suggest that NAA alters proteins levels and smooth muscle contractility and these changes likely to contribute to gastrointestinal disorder seen in these diseases.
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Affiliation(s)
- Sankar Surendran
- Department of Pediatrics, University of Texas Health Science Center, Houston, TX 77030, USA.
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Abstract
Canavan's disease is an autosomal recessive disorder caused by aspartoacylase deficiency. The deficiency of aspartoacylase leads to increased concentration of N-acetylaspartic acid in brain and body fluids. The failure to hydrolyze N-acetylaspartic acid causes disruption of myelin, resulting in spongy degeneration of the white matter of the brain. The clinical features of the disease are hypotonia in early life, which changes to spasticity, macrocephaly, head lag, and progressive severe mental retardation. Although Canavan's disease is panethnic, it is most prevalent in the Ashkenazi Jewish population. Research at the molecular level led to the cloning of the gene for aspartoacylase and development of a knockout mouse for Canavan's disease. These developments have afforded new tools for research in the attempts to understand the pathophysiology of Canavan's disease, design new therapies, and explore methods for gene transfer to the central nervous system.
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Affiliation(s)
- Sankar Surendran
- Department of Pediatrics, The University of Texas Medical Branch, Galveston, TX 77555-0359, USA
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Surendran S, Michals-Matalon K, Quast MJ, Tyring SK, Wei J, Ezell EL, Matalon R. Canavan disease: a monogenic trait with complex genomic interaction. Mol Genet Metab 2003; 80:74-80. [PMID: 14567959 DOI: 10.1016/j.ymgme.2003.08.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Canavan disease (CD) is an inherited leukodystrophy, caused by aspartoacylase (ASPA) deficiency, and accumulation of N-acetylaspartic acid (NAA) in the brain. The gene for ASPA has been cloned and more than 40 mutations have been described, with two founder mutations among Ashkenazi Jewish patients. Screening of Ashkenazi Jews for these two common mutations revealed a high carrier frequency, approximately 1/40, so that programs for carrier testing are currently in practice. The enzyme deficiency in CD interferes with the normal hydrolysis of NAA, which results in disruption of myelin and spongy degeneration of the white matter of the brain. The clinical features of the disease are macrocephaly, head lag, progressive severe mental retardation, and hypotonia in early life, which later changes to spasticity. A knockout mouse for CD has been generated, and used to study the pathophysiological basis for CD. Findings from the knockout mouse indicate that this monogenic trait leads to a series of genomic interaction in the brain. Changes include low levels of glutamate and GABA. Microarray expression analysis showed low level of expression of GABA-A receptor (GABRA6) and glutamate transporter (EAAT4). The gene Spi2, a gene involved in apoptosis and cell death, showed high level of expression. Such complexity of gene interaction results in the phenotype, the proteome, with spongy degeneration of the brain and neurological impairment of the mouse, similar to the human counterpart. Aspartoacylase gene transfer trial in the mouse brain using adenoassociated virus (AAV) as a vector are encouraging showing improved myelination and decrease in spongy degeneration in the area of the injection and also beyond that site.
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Affiliation(s)
- Sankar Surendran
- Department of Pediatrics, Children's Hospital, The University of Texas Medical Branch, Galveston, TX 77555-0359, USA
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Abstract
Canavan disease is a severe leukodystrophy more common among Ashkenazi Jews. The enzyme defect, apartoacylase, has been identified, and the gene cloned. Only two mutations account for over 98% of all Jewish alleles with Canavan disease. The carrier frequency among healthy Jews is 1:37-58. Carrier detection and prenatal diagnosis can be accurately carried out using molecular analysis. When mutations are unknown, analysis of amniotic fluid for NAA using stable isotope dilution technique can be used for prenatal diagnosis.
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Affiliation(s)
- Reuben Matalon
- Department of Pediatrics and Human Biological Chemistry and Genetics, Children's Hospital, Galveston, TX 77555-0359, USA.
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Tarantal AF, O'Rourke JP, Case SS, Newbound GC, Li J, Lee CI, Baskin CR, Kohn DB, Bunnell BA. Rhesus monkey model for fetal gene transfer: studies with retroviral- based vector systems. Mol Ther 2001; 3:128-38. [PMID: 11237669 DOI: 10.1006/mthe.2000.0255] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many life-threatening conditions that can be diagnosed early in gestation may be treatable in utero using gene therapy. In order to determine in utero gene transfer efficiency and safety, studies were conducted with fetal rhesus monkeys as a model for the human. Included in these studies were Moloney murine leukemia virus (MLV)-based amphotropic retrovirus, vesicular stomatitis virus-G (VSV-G) pseudotyped MLV, and a VSV-G pseudotyped HIV-1-based vector, all expressing the enhanced green fluorescent protein (EGFP) as a reporter gene and driven by a cytomegalovirus-immediate early promoter (N = 16). Rhesus monkey fetuses were administered viral vector supernatant preparations by the intraperitoneal (ip) (N = 14) or intrahepatic (ih) (N = 2) routes via ultrasound guidance at 55 +/- 5 days gestation (late first trimester; term 165 +/- 10 days). Fetuses were monitored sonographically, specimens were collected prenatally and postnatally, and tissue harvests were performed at birth or 3 or 6 months postnatal age (3-10 months post-gene transfer). PCR analyses demonstrated that transduced cells were present at approximately 1.2% in peripheral blood mononuclear cells from fetuses administered amphotropic MLV, <0.5% in fetuses receiving MLV/VSV-G, and approximately 4.2% for the lentiviral vector, which decreased to 2% at birth. Hematopoietic progenitors showed that overall (mean of all time points assessed), approximately 25% of the collected colonies were positive for the EGFP transgene with the lentiviral vector, which was significantly greater than results achieved with the MLV-based vector systems (4-9%; P < or = 0.001-0.016). At necropsy, 0.001-10% of the total genomic DNA was positive for EGFP in most tissues for all groups. EGFP-positive fluorescent cells were found in cell suspensions of thymus, liver, spleen, lymph nodes, cerebral cortex, and bone marrow (0.5-6%). Overall, the results of these studies have shown: (1) healthy infants expressing vector sequences up to 10 months post-gene transfer, (2) fetal primate administration of retroviral vectors results in gene transfer to multiple organ systems, (3) the highest level of gene transfer to hematopoietic progenitors was observed with the lentiviral vector system, and (4) there was no evidence of transplacental transfer of vector sequences into the dams. The rhesus monkey is an important preclinical primate model system for exploring gene transfer approaches for future applications in humans.
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Affiliation(s)
- A F Tarantal
- California Regional Primate Research Center, University of California at Davis, 95616-8542, USA.
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Abstract
Canavan disease, spongy degeneration of the brain, is an autosomal recessive disorder with increased prevalence among Ashkenazi Jews. The biochemical marker for this disease is increased levels of N-acetylaspartic acid, due to the defective enzyme, aspartoacylase. This discovery allowed for accurate diagnosis of the disease. The gene for aspartoacylase has been cloned and two mutations have been found to be responsible for Canavan disease among Ashkenazi Jewish patients in 98% of the cases. Molecular analysis of healthy Jewish individuals for these mutations has resulted in an unexpectedly high carrier frequency for Canavan disease among Jews. Therefore, carrier testing of the Jewish population is possible and indicated.
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Affiliation(s)
- R Matalon
- Department of Pediatric and Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77555-0359, USA
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Affiliation(s)
- R Matalon
- Department of Pediatrics, University of Texas Medical Branch at Galveston, 301 University Boulevard, Galveston, TX 77555-0359, USA.
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Elpeleg ON, Shaag A. The spectrum of mutations of the aspartoacylase gene in Canavan disease in non-Jewish patients. J Inherit Metab Dis 1999; 22:531-4. [PMID: 10407784 DOI: 10.1023/a:1005512524957] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Canavan disease is an infantile neurodegenerative disease that is caused by mutations in the gene encoding the enzyme aspartoacylase. It has mainly been reported in Jewish families. Genotyping of newly diagnosed patients is essential for the carrier identification and prenatal diagnosis. The sequence of the coding region was determined in 15 non-Jewish patients and 9 new mutations were identified: Y109X, P183H, V186F, M195R, P280L, P280S, A287T, 245insA, and a tentative missplicing mutation which leads to skipping of exon 5. The common pan-European mutation, A305E, was identified in 40% of the alleles and the overall detection rate was 93%.
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Affiliation(s)
- O N Elpeleg
- Metabolic Disease Unit, Shaare-Zedek Medical Center, Jerusalem, Israel
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Besley GT, Elpeleg ON, Shaag A, Manning NJ, Jakobs C, Walter JH. Prenatal diagnosis of Canavan disease--problems and dilemmas. J Inherit Metab Dis 1999; 22:263-6. [PMID: 10384383 DOI: 10.1023/a:1005534105933] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- G T Besley
- Willink Biochemical Genetics Unit, Royal Manchester Children's Hospital, UK.
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Abstract
Canavan in 1931 described spongy degeneration of the brain in a child who was thought to have had Schilder's disease. Since that classic histological description, Canavan disease has become a distinct clinical entity, with the recognition by Van Bogaert and Bertrand that this is an autosomal recessive disease prevalant among children of Jewish extraction. Recent advances in the understanding of the biochemical defect led to an increase in awareness and ease in diagnosis, and indeed the disease is not as rare as initially thought. Exploring the molecular aspects of Canavan disease has led to exciting new developments in carrier detection and prevention of Canavan disease. Work is underway in our laboratory to develop a knock-out mouse for Canavan disease for understanding of the pathophysiology of this disease and formulating gene therapy.
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Affiliation(s)
- R Matalon
- Department of Pediatrics, University of Texas Medical Branch at Galveston, USA.
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Affiliation(s)
- R Matalon
- Department of Pediatrics, University of Texas Medical Branch at Galveston, USA
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Baslow MH, Resnik TR. Canavan disease. Analysis of the nature of the metabolic lesions responsible for development of the observed clinical symptoms. J Mol Neurosci 1997; 9:109-25. [PMID: 9407392 DOI: 10.1007/bf02736855] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Canavan disease (CD), a rare recessive autosomal genetic disorder, is characterized by early onset and a progressive spongy degeneration of the brain involving loss of the axon's myelin sheath. After a relatively normal birth, homozygous individuals generally develop clinical symptoms within months, and usually die within several years of the onset of the disease. A biochemical defect associated with this disease results in reduced activity of the enzyme N-acetyl-L-aspartate amidohydrolase (aspartoacylase) and affected individuals have less ability to hydrolyze N-acetyl-L-asparate (NAA) in brain and other tissues. As a result of aspartoacylase deficiency, NAA builds up in extracellular fluids (ECF) and is excreted in urine. From an analysis of the NAA biochemical cycle in various tissues of many vertebrate species, evidence is presented that there may be two distinct NAA circulation patterns related to aspartoacylase activity. These include near-field circulations in the brain and the eye, and a far-field systemic circulation involving the liver and kidney, the purpose of which in each case is apparently to regenerate aspartate (Asp) in order for it to be recycled into NAA as part of the still unknown function of the NAA cycle. Based on the authors' analysis, they have also identified several metabolic outcomes of the genetic biochemical aspartoacylase lesion. First, there is a daily induced Asp deficit in the central nervous system (CNS) that is at least six times the static level of available free Asp. Second, there is up to a 50-fold drop in the intercompartmental NAA gradient, and third, the ability of the brain to perform its normal intercompartmental cycling of NAA to Asp is terminated, and as a result, the only remaining long-term source of Asp for NAA synthesis is via nutritional supplementation of Asp or its metabolic precursors. Finally, the authors identify a potential maternal-fetal interaction that may be responsible for observed normal fetal development in utero, and that provides a rationale for, and suggests how, CD might respond to far-field nutritional, transplantation, or genetic engineering techniques to alter the course of the disease.
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Affiliation(s)
- M H Baslow
- Nathan S. Kline Institute for Psychiatric Research, Center for Neurochemistry, Orangeburg, NY 10962, USA
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Abstract
Establishing the basic defect in Canavan disease has led to reliable biochemical methods for the diagnosis of this disease. The isolation of the gene and identification of mutations causing Canavan disease have led to the possibility of using DNA methods for the diagnosis of Canavan disease and for carrier detection. A surprising finding is the high carrier frequency of this gene defect among Ashkenazi Jewish people. Analysis for two mutations leads to the identification of 97% of Jewish patients with Canavan disease, and screening of Ashkenazi Jews is possible. N-Acetylaspartic acid has been considered to be an inert compound. The pathophysiology of Canavan disease links lack of NAA hydrolysis to a severe, debilitating white matter disease. Currently, NAA is being studied in many other brain disorders, such as Alzheimer disease, Huntington disease, and stroke. However, the only disease with a specific defect in the metabolism of NAA is Canavan disease. An animal model for Canavan disease is needed to study some of the questions regarding the role of NAA in brain tissue, and for the study of therapeutic modalities, including gene therapy.
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Affiliation(s)
- R Matalon
- Research Institute, Miami Children's Hospital, Fl 33155-3009, USA
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Abstract
N-Acetyl aspartate (NAA) is the second most abundant amino acid in the human brain. NAA is synthesized by L-aspartate N-acetyl transferase or by cleavage from N-acetyl aspartyl glutamate by N-acylated alpha-linked L-amino dipeptidase (NAALADase); and it is catabolized to acetate and aspartate by N-acetyl aspartate amino hydrolase (amino acylase II). NAA is localized primarily to neurons, where it is concentrated in the cytosol. Although NAA is devoid of neurophysiological effects, it serves as an acetyl donor, an initiator of protein synthesis or a carbon transfer source across the mitochondrial membrane. The concentration of NAA in human brain increases 3-fold between midgestation and adulthood. In Canavan's Disease, an autosomal recessive disorder due to a null mutation in amino acylase II, NAA levels in brain are markedly increased and disrupt myelination. NAA levels have been found to be reduced in neurodegenerative disorders, including Alzheimer's Disease and Huntington's Disease. Since endogenous NAA can be readily detected in human brain by magnetic resonance spectroscopy, it is increasingly being exploited as a marker for functional and structural integrity of neurons in an expanding number of disorders.
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Affiliation(s)
- G Tsai
- Laboratory of Molecular and Developmental Neuroscience, Massachusetts General Hospital, Belmont 02178, USA
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Matalon R, Kaul R, Gao GP, Michals K, Gray RG, Bennett-Briton S, Norman A, Smith M, Jakobs C. Prenatal diagnosis for Canavan disease: the use of DNA markers. J Inherit Metab Dis 1995; 18:215-7. [PMID: 7564250 DOI: 10.1007/bf00711770] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- R Matalon
- Research Institute, Miami Children's Hospital, FL 33155, USA
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Elpeleg ON, Shaag A, Anikster Y, Jakobs C. Prenatal detection of Canavan disease (aspartoacylase deficiency) by DNA analysis. J Inherit Metab Dis 1994; 17:664-6. [PMID: 7707689 DOI: 10.1007/bf00712008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Amniocentesis was performed in four pregnancies at risk for Canavan disease (CD). In all families both parents were of Ashkenazi-Jewish origin and harboured the C854 mutation in the cDNA of the aspartoacylase gene. Using DNA analysis of the amniotic cells, three fetuses were predicted to be non-affected and one fetus was predicted to be affected. The concentration of N-acetylaspartic acid (NAA) in the amniotic fluid was in agreement with these results. In urine samples of the three newborns predicted to be non-affected, the concentration of NAA was normal. Tissues of the aborted fetus were not available. We conclude that DNA analysis is probably a reliable method for prenatal diagnosis of CD.
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Affiliation(s)
- O N Elpeleg
- Metabolic Unit, Shaare-Zedek Medical Center, Jerusalem, Israel
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Rolland MO, Mandon G, Bernard A, Zabot MT, Mathieu M. Unreliable verification of prenatal diagnosis of Canavan disease: aspartoacylase activity in deficient and normal fetal skin fibroblasts. J Inherit Metab Dis 1994; 17:748. [PMID: 7707699 DOI: 10.1007/bf00712018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- M O Rolland
- Centre d'Etude des Maladies Métaboliques, Hôpital Debrousse, Lyon, France
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