Spinal Muscular Atrophy, Diagnostic Test (Sendout)

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General Information

Lab Name
Lab Code
662
External Test Id
LAB1912
Description

Description: Spinal muscular atrophy (SMA) causes progressive muscular weakness and degeneration by loss of anterior horn cells in the brain stem and spinal cord. Approximately 95-98% of individuals with SMA are homozygous for a deletion of exons 7 & 8 of the SMN1 gene. The remaining 2%-5% of individuals with SMA are compound heterozygotes for a deletion in combination with a point mutation within the SMN1 gene. Increases in SMN2 gene copy number often modify the phenotype. This test will determine the copy number of both the SMN1 and SMN2 genes.

This test can be used for: Diagnostic testing in an individual suspected to have SMA.

Ordering Requirements:

Ordering Note: To order the SMA Carrier Test, refer to Spinal Muscular Atrophy, Carrier Test (Sendout) [RSMACT].

Forms & Requisitions
Synonyms
LAB1912, SMA, SMA Diagnostic, SMA Type 1, SMN1, SMN2

Interpretation

Method

Multiple ligation-dependent probe amplification (MLPA) of exons 7&8 in SMN1 & SMN2 genes

Ref. Range Notes

An interpretive report will be provided.

Interferences and Limitations

Limitations: 95-98% of individuals with SMA have SMN1 deletions which can be detected using this technique. The remaining 2-5% of individuals with SMA have a point mutation within the SMN1 gene that is not detected by this test.

Ordering & Collection

Specimen Type
Blood, Cord Blood
Collection

3 mL whole blood/cord blood in LAVENDER (EDTA) top tube

Also Accepted: Yellow ACD (A or B)

  • Contact SCH Molecular Genetics Lab directly at 206-987-3872 to discuss submission of other sample types.

Unacceptable: Heparinized samples.

Forms & Requisitions
Handling Instructions

Outside Laboratories:

  • Refrigerate blood samples prior to shipment. Transport samples at room temperature.
  • A completed SCH Laboratory Molecular Genetics requisition must accompany the sample.

Stability: Ambient: 3-5 days; Refrigerated: 7 days; Frozen: Unacceptable.

  • Note: Whole blood samples >7 days old may still be submitted to SCHL to be assessed for acceptability.
Quantity
requested: 3 mL whole blood
minimum: 1 mL whole blood

Processing

Processing

Hold blood samples at room temperature if sending same-day. If shipment is delayed, refrigerate sample until sending.

Login: GSEND1-;ROOM TEMP

  • GSNDT1: SCHL
  • GSTYP1: WB (or CORDB)
  • GTSRQ1: ;Spinal Muscular Atrophy, Diagnostic Test (SCHL Test LAB1912)

Sendouts:

  • Seattle Children's Hospital Lab Test: LAB1912.
  • Send samples at ambient temperature with a completed SCHL Genetics requisition via DLMP or Delivery Express courier. If shipment is delayed, refrigerate sample until ready to send.
  • Samples not sent out same day as collection should be refrigerated prior to shipment, and then sent at room temp.

Stability: Ambient: 3-5 days; Refrigerated: 7 days; Frozen: Unacceptable.

  • Note: Whole blood samples >7 days old may still be submitted to SCHL to be assessed for acceptability.

Performance

LIS Dept Code
Performing Location(s)
Sendout Seattle Children's Hospital Department of Laboratories
206-987-2617

4800 Sand Point Way NE
OC.8.720
Seattle, WA 98105
Other Locations/Notes

SCH Molecular Genetics Laboratory: (206) 987-3872

Frequency
Performed: Monday-Friday. Turnaround time: 2 weeks.
Available STAT?
No

Billing & Coding

CPT codes
Billing Comments

CPT: 81329

LOINC