Friedreich Ataxia Repeat Expansion Analysis (Sendout)

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General Information

Lab Name
Lab Code
553
External Test Id
6031
Description

Test Description: Long PCR analysis across the GAA region of the FXN gene to determine allele sizes. Southern analysis is used to identify extremely large GAA repeat expansions and to confirm the PCR results.

Indications for Testing:

  • Patients with a clinical or suspected diagnosis of Friederich’s ataxia
  • Symptomatic or presymptomatic patients with a family history of Friederich’s ataxia
  • Patients who are planning a pregnancy (carrier screening) with a family history of Friederich’s ataxia

Ordering Requirements:

  • Orders must be accompanied by a completed Baylor Genetics requisition. [See page 5 of 13 for test 6031, Friedreich Ataxia Repeat Expansion Analysis.]
References
Synonyms
6031, Ataxia-Friedreich, FXN, Recessive Ataxia
Components

Interpretation

Method

Southern Blot, PCR

Reference Range
Ref. Range Notes
Unaffected: 5-33 repeats
Premutation carrier: 34-65 repeats
Full mutation, Friedreich ataxia: 66-~1300 repeats
Interferences and Limitations

Limitations: All normal sized alleles and most expanded alleles will be detected in this analysis. Southern blot analysis is used to identify extremely large GAA repeat expansions and to confirm the PCR results. Allele sizes will be reported as approximations and size ranges are subject to change as more information becomes available.

References

Ordering & Collection

Specimen Type
Blood
Collection

5 mL blood in LAVENDER TOP (EDTA) tube

Infants <2 years: 3 mL blood in LAVENDER (EDTA) tube

Handling Instructions

Outside Laboratories:

  • Store and transport whole blood at ambient temperature.
  • Expedite transport to the lab. Samples should be received at Baylor within 48 hours of collection. Allow for a day of transport from UWMT to Baylor.
  • Submit a completed Baylor Genetics requisition along with the DLMP requisition.* Leave the billing section to be completed by Sendouts staff.
    • *Use client-specific requisition when available. To obtain a client-specific requisition, contact Client Support Services via email at: commserv@uw.edu.
Quantity
Requested: 5 mL EDTA whole blood
Minimum: 3 mL EDTA whole blood

Processing

Receiving Instructions

Store whole blood at ambient temperature.

Login: GSEND1-;ROOM TEMP WB

  • GSNDT1: BAYMIR
  • GSTYP1: WB
  • GTSRQ1: ;Friedreich Ataxia Repeat Expansion Analysis (Baylor Test 6031)

Sendouts:

  • Baylor Test: 6031
  • Ship samples Monday through Friday via FedEx Priority Overnight.
    • If shipping on a Friday, select the FedEx Saturday Delivery option.
  • Samples should arrive at Baylor within 48 hours of sample collection. For delays, contact Baylor regarding the acceptibility of the sample.

Stability: Ambient (preferred): 48 hours; Frozen: Unacceptable.

Misc Sendout

Performance

Lab Department
Frequency
Turn Around Time: 21 days from sample receipt at Baylor Genetics Laboratory.
Available STAT?
No
Performing Location(s)
Sendout Baylor Miraca Genetics Laboratories, LLC
800-411-4363

2450 Holcombe Blvd.
Houston, TX 77021

Billing & Coding

Billing Comments

CPT: 81284