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Test Code SMNDX Spinal Muscular Atrophy Diagnostic Assay, Deletion/Duplication Analysis, Varies

Reporting Name

SMA Diagnostic by Del/Dup

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

First-tier newborn screening for spinal muscular atrophy (SMA)

 

Prenatal testing for SMA

 

Diagnostic testing to confirm a suspected diagnosis of SMA

Method Name

Dosage Analysis by Digital Droplet Polymerase Chain Reaction (ddPCR)


Additional Testing Requirements


All prenatal specimens must be accompanied by a maternal blood specimen; order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.



Shipping Instructions


Specimen preferred to arrive within 96 hours of collection.



Specimen Required


Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. For instructions for testing patients who have received a bone marrow transplant, call 800-533-1710.

 

Submit only 1 of the following specimens:

 

Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA) or yellow top (ACD)

Acceptable: Any anticoagulant

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

Additional Information: To ensure a minimum DNA amount and concentration, the preferred blood volume must be submitted. Testing may be canceled if the specimen supplied is inadequate. 

Specimen Stability Information: Ambient (preferred) 4 days/Refrigerated 14 days

 

Prenatal Specimens

Due to its complexity, consultation with the laboratory is required for all prenatal testing; call 800-533-1710 to speak to a genetic counselor. 

 

Submit only 1 of the following specimens:

 

Specimen Type: Amniotic fluid

Container/Tube:

Preferred: Screw-capped, sterile centrifuge tubes

Acceptable: T-25 flasks of confluent cultured cells

Specimen Volume: 20 mL

Specimen Stability Information: Refrigerated (preferred)/Ambient

 

Specimen Type: Chorionic villi

Container/Tube:

Preferred: 15-mL tube containing 15 mL of transport media

Acceptable: T-25 flasks of confluent cultured cells

Specimen Volume: 20 mg

Specimen Stability Information: Refrigerated

 

Specimen Type: Blood spot

Container/Tube:

Preferred: Collection card (Whatman Protein Saver 903 Paper)

Acceptable: Perkin Elmer 226 (formerly Ahlstrom 226) filter paper, or Blood Spot Collection Card

Specimen Volume: 5 Blood spots

Collection Instructions:

1. An alternative blood collection option for a patient >1 year of age is a finger stick.

2. Let blood dry on the filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.

3. Do not expose specimen to heat or direct sunlight.

4. Do not stack wet specimens.

5. Keep specimen dry

Specimen Stability Information: Ambient (preferred)/Refrigerated

Additional Information:

1. For collection instructions, see Blood Spot Collection Instructions in Special Instructions.

2. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777) in Special Instructions.

3. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800) in Special Instructions.


Specimen Type

Varies

Specimen Minimum Volume

Blood: 1 mL
Amniotic Fluid: 10 mL
Chorionic villi: 5 mg

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Varies

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

An interpretive report will be provided.

Interpretation

An interpretive report will be provided.

Day(s) Performed

Varies

Report Available

5 to 10 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

81329

88235 (if appropriate)

88240 (if appropriate)

88233 (if appropriate)

88240 (if appropriate)

81265 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SMNDX SMA Diagnostic by Del/Dup 49857-6

 

Result ID Test Result Name Result LOINC Value
113452 Result Summary 50397-9
113453 Result 49857-6
113454 Interpretation 69047-9
113455 Additional Information 48767-8
113456 Specimen 31208-2
113457 Source 31208-2
113458 Released By 18771-6

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Molecular Genetics: Congenital Inherited Diseases Patient Information (T521) in Special Instructions.

3. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
CULAF Amniotic Fluid Culture/Genetic Test Yes No
CULFB Fibroblast Culture for Genetic Test Yes No
MATCC Maternal Cell Contamination, B Yes No

Testing Algorithm

For prenatal specimens only: If amniotic fluid (nonconfluent cultured cells) is received, amniotic fluid culture/genetic test will be added at an additional charge.

 

If chorionic villus specimen (nonconfluent cultured cells) is received, fibroblast culture for genetic test will be added per laboratory protocol at an additional charge.

 

For any prenatal specimen that is received, maternal cell contamination testing will be added per laboratory protocol at an additional charge.

 

If the patient has abnormal newborn screening result for spinal muscular atrophy, immediate action should be taken. Refer to the appropriate American College of Medical Genetics and Genomics Newborn Screening ACT Sheet(1).

 

The following algorithms are available:

-Inherited Motor Neuron Disease and Dementia Testing Algorithm

-Spinal Muscular Atrophy Testing Algorithm