Myotonic Dystrophy Type 1 Repeat Expansion (Sendout)

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General Information

Lab Name
Lab Code
494
External Test Id
6041
Description

Test Description: Repeat expansion analysis is performed to determine the number of CTG repeats in the DMPK gene.

Indications for Testing:

  • Patients with a clinical or suspected diagnosis of myotonic dystrophy
  • Symptomatic or presymptomatic patients with a family history of myotonic dystrophy
  • Patients who are planning a pregnancy (carrier screening) with a family history of myotonic dystrophy

Ordering Requirements:

  • Providers must submit a completed Baylor Genetics Requisition with the order. DM1 is listed on page 8 (test code 6041).
References
Forms & Requisitions
Synonyms
6041, DM1, DMPK gene, Dystrophia Myotonica, Muscular Myotonic Dystrophy, Repeat Expansion Analysis, Steinert’s Disease

Interpretation

Method

Analysis of DMPK gene by PCR-amplification, Southern Blot with densitometry

Ref. Range Notes
Unaffected: 5-34 repeats
Premutation carrier: 35-49 repeats
Full mutation, myotonic dystrophy: ≥ 50 repeats
References

Ordering & Collection

Specimen Type
Blood
Collection

5 mL blood in LAVENDER TOP (EDTA) tube

  • Pediatric: 3 mL blood in LAVENDER TOP (EDTA) tube
Forms & Requisitions
Handling Instructions

Outside Laboratories: Refrigerate whole blood and expedite transport to the lab. A completed Baylor requisition is required.

Quantity
requested: 5 mL EDTA whole blood
minimum: 3 mL EDTA whole blood

Processing

Processing

Store and transport whole blood at room temperature. If shipment is delayed, samples may be refrigerated for up to 7 days.

Login: GSEND1-;ROOM TEMP

  • GSNDT1: BAYMIR
  • GSTYP1: WB
  • GTSRQ1: ;Myotonic Dystrophy, Type 1 (Baylor Test 6041)

Sendouts:

  • Ship whole blood at room temperature in an insulated container FedEx Overnight.
    • If sample will not be shipped the date of collection, refirgerate sample while awaiting shipment, and send refrigerated.
  • If shipping samples on a Friday, select the "Saturday Delivery" option when creating the FedEx shipping label.

Stability: Ambient: Preferred. If shipment is delayed, samples may be refrigerated for up to 7 days. Do not heat or freeze the sample.

Performance

LIS Dept Code
Performing Location(s)
Sendout Baylor Miraca Genetics Laboratories, LLC
800-411-4363

2450 Holcombe Blvd.
Houston, TX 77021
Frequency
Turn around Time: 21 days from sample receipt.
Available STAT?
No

Billing & Coding

CPT codes
LOINC