Molecular characterization of a novel HEXA mutation at the +3 position of intron 8 in a Tay-Sachs disease patient

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · American Journal of Human Genetics

OSTI ID:134768

Richard, M; Triggs-Raine, B ^[1]; Natowicz, M ^[2]

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1. Univ. of Manitoba, Winnipeg (Canada)
2. E.K. Shriver Center, Waltham, MA (United States)

Tay-Sachs disease is an autosomal recessive lysosomal storage disorder resulting from mutations in the HEXA gene that cause a deficiency in the activity of that enzyme {beta}-hexosaminidase A (Hex A). This deficiency leads to the build-up of G{sub M2} ganglioside, resulting in neurodegeneration and death. Biochemical analysis of a non-Jewish patient with a late-infantile form of Tay-Sachs disease revealed a substantial level of Hex A activity (38.4%) when 4-MUG was used as the substrate. However, when a substrate (4-MUGS) specific for the {alpha}-subunit of Hex A ({alpha}{beta}) was used, almost no activity was detected in the HEXA gene of the patient using SSCP analysis followed by sequencing. The first mutation, a G533A substitution in exon 5, is previously described and associated with the B1 form of Tay-Sachs disease. The second mutation is a novel a-to-g base change at the +3 position of intron 8. This was confirmed using the AIRS method, whereby a MaeIII site was created in the presence of the mutation. Normal and patient mRNA was reverse transcribed and exons 7 to 9 were PCR-amplified from the cDNA. An abnormally sized amplification product detected only in the patient cDNA was sequenced; exon 8 had been deleted and exons 7 and 9 were spliced together. A substantial level of normally-sized PCR product was also detected in the patient`s cDNA. Experiments are in progress to determine if this is produced from the allele harboring the G533A mutation. Given that previous mutations of this type have been associated with 97-100% abnormal splicing, this mutation is likely to be the cause, together with the G533A mutation, of Tay-Sachs disease in this patient.

• OSTI ID: 134768
• Report Number(s): CONF-941009--
• Journal Information: American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: Suppl.3 Vol. 55; ISSN AJHGAG; ISSN 0002-9297
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
AGE DEPENDENCE
DETECTION
DNA SEQUENCING
ENZYME ACTIVITY
EXONS
GENE MUTATIONS
GENES
INTRONS
LYSOSOMES
MESSENGER-RNA
METABOLIC DISEASES
MORTALITY
NERVOUS SYSTEM DISEASES
NUCLEOTIDES
PATIENTS
PHENOTYPE
POLYMERASE CHAIN REACTION
RECESSIVE MUTATIONS
SPLICING
STORAGE
TRANSCRIPTION