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Test Identifier Information

Registration CodeMUTA 26

Exon 5 of the TOR1A gene is analysed by bidirectional automated DNA sequencing.

Diagnostic Use / Indications

TOR1A sequencing may be used to confirm a diagnosis of early-onset torsion dystonia (DYT1). Early-onset torsion dystonia represents the commonest and most severe form of hereditary dystonia. It is an autosomal dominantly inherited movement disorder characterised by twisting muscle contractures that usually begins in childhood. Almost all cases are due to a deletion of nucleotides 904 to 906 of the TOR1A gene on chromosome 9q34 resulting in the loss of one of a pair of glutamic acid residues in a conserved region of the ATP-binding protein torsinA. Penetrance is estimated at 30% (70% of individuals who inherit the mutation do not develop DYT1).

Constituent TestsGenomic DNA Extraction ;
External Price$196.06(Exclusive of GST)

Specimen Collection

Pre-Testing Requirements

Most individuals with DYT1 will have an affected parent, and sibs at 50% risk. It is appropriate to offer genetic counselling to individuals and families seeking a diagnosis of DYT1 in order to help them make informed decisions about testing. Genetic counselling is available in NZ from Northern Regional Genetics Services (Ph 0800-476-123) or Central and Southern Regional Genetic Services (Ph 0508-364-436).


Patient Specimen4.0mL EDTA,
Paediatric Specimen0.5 mL - 1 mL EDTA blood
Sample Delivery to LabAmbient

CHLabs Laboratory

DepartmentBiochemistry - Molecular Pathology
Contact Details Email Email
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Contact Phone Number03 3640 548
Test Availability9am to 5pm, Monday to Friday
Turnaround TimeWithin 4 weeks
Reference Interval

NCBI Reference Sequence: NM_000113.2


Detection of the TOR1A:c.904_906delGAG establishes a diagnosis of DYT1 in symptomatic individuals.

Uncertainty of Measurement

Automated bidirectional DNA sequencing has an analytical sensitivity and specificity of >99%. Note that the lower limit of variant detection of sequencing analysis is ~10%, this is important to consider in the case of mosaicism, mitochondrial, and somatic variation that is not expected to be present at 50% or 100%.  This analysis will not detect variants located within intronic regions, except at the intron-exon boundaries.

Additional Information
  1. This genetic test needs nucleated cells. Please don’t centrifuge or freeze the EDTA blood tube.
  2. Genomic DNA must be extracted from the specimen prior to testing. This incurs an additional charge (see GDNA). Laboratories may prefer to submit DNA for testing. Please provide a minimum of 5 micrograms of DNA at 20 nanograms / microlitre.
  3. If storing blood tube prior to delivery please refrigerate at 4 degrees (transport still at ambient temperature).

Delphic Number Test Number4587

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