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. 1992 Oct;51(4):802–809.

A double mutation in exon 6 of the beta-hexosaminidase alpha subunit in a patient with the B1 variant of Tay-Sachs disease.

P J Ainsworth 1, M B Coulter-Mackie 1
PMCID: PMC1682773  PMID: 1415222

Abstract

The B1 variant form of Tay-Sachs disease is enzymologically unique in that the causative mutation(s) appear to affect the active site in the alpha subunit of beta-hexosaminidase A without altering its ability to associate with the beta subunit. Most previously reported B1 variant mutations were found in exon 5 within codon 178. The coding sequence of the alpha subunit gene of a patient with the B1 variant form was examined with a combination of reverse transcription of mRNA to cDNA, PCR, and dideoxy sequencing. A double mutation in exon 6 has been identified: a G574----C transversion causing a val192----leu change and a G598----A transition resulting in a val200----met alteration. The amplified cDNAs were otherwise normal throughout their sequence. The 574 and 598 alterations have been confirmed by amplification directly from genomic DNA from the patient and her mother. Transient-expression studies of the two exon 6 mutations (singly or together) in COS-1 cells show that the G574----C change is sufficient to cause the loss of enzyme activity. The biochemical phenotype of the 574 alteration in transfection studies is consistent with that expected for a B1 variant mutation. As such, this mutation differs from previously reported B1 variant mutations, all of which occur in exon 5.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ainsworth P. J., Surh L. C., Coulter-Mackie M. B. Diagnostic single strand conformational polymorphism, (SSCP): a simplified non-radioisotopic method as applied to a Tay-Sachs B1 variant. Nucleic Acids Res. 1991 Jan 25;19(2):405–406. doi: 10.1093/nar/19.2.405. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bayleran J., Hechtman P., Saray W. Synthesis of 4-methylumbelliferyl-beta-D-N-acetylglucosamine-6-sulfate and its use in classification of GM2 gangliosidosis genotypes. Clin Chim Acta. 1984 Nov 15;143(2):73–89. doi: 10.1016/0009-8981(84)90215-8. [DOI] [PubMed] [Google Scholar]
  3. Biggin M. D., Gibson T. J., Hong G. F. Buffer gradient gels and 35S label as an aid to rapid DNA sequence determination. Proc Natl Acad Sci U S A. 1983 Jul;80(13):3963–3965. doi: 10.1073/pnas.80.13.3963. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Brown C. A., Mahuran D. J. Active arginine residues in beta-hexosaminidase. Identification through studies of the B1 variant of Tay-Sachs disease. J Biol Chem. 1991 Aug 25;266(24):15855–15862. [PubMed] [Google Scholar]
  5. Brown C. A., Neote K., Leung A., Gravel R. A., Mahuran D. J. Introduction of the alpha subunit mutation associated with the B1 variant of Tay-Sachs disease into the beta subunit produces a beta-hexosaminidase B without catalytic activity. J Biol Chem. 1989 Dec 25;264(36):21705–21710. [PubMed] [Google Scholar]
  6. Devereux J., Haeberli P., Smithies O. A comprehensive set of sequence analysis programs for the VAX. Nucleic Acids Res. 1984 Jan 11;12(1 Pt 1):387–395. doi: 10.1093/nar/12.1part1.387. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Elliott J., Coulter-Mackie M. B., Jung J. H., Rodenhiser D. I., Singh S. M. A method for transforming lymphocytes from very small blood volumes suitable for paediatric samples. Hum Genet. 1991 Apr;86(6):615–616. doi: 10.1007/BF00201551. [DOI] [PubMed] [Google Scholar]
  8. Gordon B. A., Gordon K. E., Hinton G. G., Cadera W., Feleki V., Bayleran J., Hechtman P. Tay-Sachs disease: B1 variant. Pediatr Neurol. 1988 Jan-Feb;4(1):54–57. doi: 10.1016/0887-8994(88)90026-4. [DOI] [PubMed] [Google Scholar]
  9. Jameson B. A., Wolf H. The antigenic index: a novel algorithm for predicting antigenic determinants. Comput Appl Biosci. 1988 Mar;4(1):181–186. doi: 10.1093/bioinformatics/4.1.181. [DOI] [PubMed] [Google Scholar]
  10. Jeanpierre M. A rapid method for the purification of DNA from blood. Nucleic Acids Res. 1987 Nov 25;15(22):9611–9611. doi: 10.1093/nar/15.22.9611. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Keohavong P., Thilly W. G. Fidelity of DNA polymerases in DNA amplification. Proc Natl Acad Sci U S A. 1989 Dec;86(23):9253–9257. doi: 10.1073/pnas.86.23.9253. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Kytzia H. J., Sandhoff K. Evidence for two different active sites on human beta-hexosaminidase A. Interaction of GM2 activator protein with beta-hexosaminidase A. J Biol Chem. 1985 Jun 25;260(12):7568–7572. [PubMed] [Google Scholar]
  13. LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
  14. Li S. C., Hirabayashi Y., Li Y. T. A new variant of type-AB GM2-gangliosidosis. Biochem Biophys Res Commun. 1981 Jul 30;101(2):479–485. doi: 10.1016/0006-291x(81)91285-7. [DOI] [PubMed] [Google Scholar]
  15. Lowden J. A. Evidence for a hybrid hexosaminidase isoenzyme in heterozygotes for Sandhoff disease. Am J Hum Genet. 1979 May;31(3):281–289. [PMC free article] [PubMed] [Google Scholar]
  16. Mahuran D. J. The biochemistry of HEXA and HEXB gene mutations causing GM2 gangliosidosis. Biochim Biophys Acta. 1991 Feb 22;1096(2):87–94. doi: 10.1016/0925-4439(91)90044-a. [DOI] [PubMed] [Google Scholar]
  17. Mahuran D. J., Triggs-Raine B. L., Feigenbaum A. J., Gravel R. A. The molecular basis of Tay-Sachs disease: mutation identification and diagnosis. Clin Biochem. 1990 Oct;23(5):409–415. doi: 10.1016/0009-9120(90)90153-l. [DOI] [PubMed] [Google Scholar]
  18. Myerowitz R., Costigan F. C. The major defect in Ashkenazi Jews with Tay-Sachs disease is an insertion in the gene for the alpha-chain of beta-hexosaminidase. J Biol Chem. 1988 Dec 15;263(35):18587–18589. [PubMed] [Google Scholar]
  19. Myerowitz R., Hogikyan N. D. Different mutations in Ashkenazi Jewish and non-Jewish French Canadians with Tay-Sachs disease. Science. 1986 Jun 27;232(4758):1646–1648. doi: 10.1126/science.3754980. [DOI] [PubMed] [Google Scholar]
  20. Myerowitz R., Piekarz R., Neufeld E. F., Shows T. B., Suzuki K. Human beta-hexosaminidase alpha chain: coding sequence and homology with the beta chain. Proc Natl Acad Sci U S A. 1985 Dec;82(23):7830–7834. doi: 10.1073/pnas.82.23.7830. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Navon R., Proia R. L. The mutations in Ashkenazi Jews with adult GM2 gangliosidosis, the adult form of Tay-Sachs disease. Science. 1989 Mar 17;243(4897):1471–1474. doi: 10.1126/science.2522679. [DOI] [PubMed] [Google Scholar]
  22. Neufeld E. F. Natural history and inherited disorders of a lysosomal enzyme, beta-hexosaminidase. J Biol Chem. 1989 Jul 5;264(19):10927–10930. [PubMed] [Google Scholar]
  23. Ohno K., Suzuki K. Mutation in GM2-gangliosidosis B1 variant. J Neurochem. 1988 Jan;50(1):316–318. doi: 10.1111/j.1471-4159.1988.tb13266.x. [DOI] [PubMed] [Google Scholar]
  24. Proia R. L., Soravia E. Organization of the gene encoding the human beta-hexosaminidase alpha-chain. J Biol Chem. 1987 Apr 25;262(12):5677–5681. [PubMed] [Google Scholar]
  25. Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Tanaka A., Ohno K., Sandhoff K., Maire I., Kolodny E. H., Brown A., Suzuki K. GM2-gangliosidosis B1 variant: analysis of beta-hexosaminidase alpha gene abnormalities in seven patients. Am J Hum Genet. 1990 Feb;46(2):329–339. [PMC free article] [PubMed] [Google Scholar]
  27. Triggs-Raine B. L., Akerman B. R., Clarke J. T., Gravel R. A. Sequence of DNA flanking the exons of the HEXA gene, and identification of mutations in Tay-Sachs disease. Am J Hum Genet. 1991 Nov;49(5):1041–1054. [PMC free article] [PubMed] [Google Scholar]

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