Myotonic Dystrophy 1 (DMPK) Genetic Testing (Repeat Expansion)

TEST: 620084
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CPT: 81234
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Special Instructions

This assay is not currently available in New York state.

Expected Turnaround Time

2 - 4 weeks

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Specimen Requirements

Specimen

Whole blood

Volume

4 mL

Minimum Volume

1 mL

Container

Lavender-top (EDTA) tube

Collection

Draw blood into EDTA tube.

Storage Instructions

Ship ASAP, but stable up to 5 days post-collection at room temperature. Do not freeze.

Stability Requirements

Temperature

Period

Room temperature

5 days

Refrigerated

5 days

Frozen

Do not freeze

Causes for Rejection

Frozen blood EDTA tube

Test Details

Use

Type 1 myotonic dystrophy results from a mutation in the DMPK gene known as a trinucleotide repeat expansion. This mutation increases in the size of the repeated CTG segment in the DMPK gene. People with type 1 myotonic dystrophy have from 50 to 5,000 CTG repeats in most cells. The number of repeats may be even greater in certain types of cells, such as muscle cells.

Limitations

Maximum reportable sizing: 150 repeats.

This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.

Methodology

Repeat-Primed PCR (QP-PCR)

For Providers

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CPT Statement/Profile Statement

The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf