Huntington Disease (Blood)

Testing Laboratory

Department

Diagnostic Genetics

Delphic Registration Code (Alpha Code)

DNAT

Test Code (Numeric Code)

7933

Laboratory Handling

Transport

Transport all bloods between >8 degrees C to <24 degrees C within 24-48 hours. If necessary specimens can be refrigerated overnight for transport at the temperatures stated, the following day. For testing of other sample types please contact the laboratory prior to sending.

Registration

Please store specimens at 4 degrees C until processed.

Sample Stability

Transport all bloods between 8 degrees to 24 degrees Celsius to the laboratory within 24-48 hours.

Synonyms

HD, Huntington's Disease

Turnaround Time

6 weeks

Urgent TAT for prenatal analysis: 2 weeks

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Acceptable

• EDTA (Microtainer)

Preferred Sample Volume (ml)

4

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Acceptable

• EDTA (Microtainer)

Preferred Sample Volume (ml)

4

Minimum Sample Volume (ml)

0.5

Additional Specimen Information

This test requires viable nucleated cells. Do not centrifuge or freeze the EDTA blood sample.

An aliquot of genomic DNA extracted by another ISO15189 accredited laboratory is also an acceptable specimen type. DNA samples should have a minimum volume of 20 µL and a concentration of at least 20 ng/µL.

If the available DNA does not meet these requirements, please contact the laboratory to discuss sample suitability and any specific testing requirements.

Additional Referral/Aliquot Information

Diagnostic testing requires referral through Genetic Services or Neurology. Juvenile HD or pregnancy related cases can only be referred only through Genetic Services.

All predictive and presymptomatic testing only through Genetic Services.

Contacts:

Genetic Health Service NZ can be contacted on 0800 476 123.

Neurology can be contacted on (09) 307 4949 ext. 25662.

The specialty of the referring clinician and the patient clinical presentation must be provided. Failure to provide the information required may delay testing.

Test Method

PCR-based amplification and subsequent fluorescence-based capillary electrophoresis is used to detect CAG repeat expansions within the Huntingtin (HTT) gene - NM_001388492.1. A Triplet-repeat Primed (TP) PCR amplification and subsequent fluorescence-based capillary electrophoresis were used to detect all sizes of expansion within the HTT gene. Due to the nature of the assay, we estimate that the CAG repeat allele sizing is correct to plus or minus one repeat for alleles ≤40 repeats and up to plus or minus two for alleles >40 repeats.

Uncertainty of Measurement

Please contact the Diagnostic Genetics Pathologist at dgen@adhb.govt.nz to discuss sources of test uncertainty, which include, but are not limited to, measurement uncertainty (MU) and biological variation.

Contact Information