Test Overview
Test Methodology

MLPA probes hybridize to target regions of SMN1 and SMN2 genes and are amplified by multiplex PCR. The amplification products are analyzed by capillary electrophoresis and SMN1 and SMN2 copy numbers are generated.

Test Usage

Detection of the copy number (deletions/duplications) of the SMN1 and SMN2 genes in patients with a clinical diagnosis of Spinal Muscular Atrophy.

Reference Range *

Interpretive report provided.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

This assay will not detect point mutations or frame-shift mutations in SMN1 or SMN2 genes.

Test Details
Days Set Up
Monday - Thursday
Analytic Time

10 days

Soft Order Code
MiChart Code
Spinal Muscular Atrophy Deletion
  • SMN1DS
  • SMN1-2 Ex 7,8 MLPA Shadow
  • SMN1D
  • SMN1-2 Ex 7,8 MLPA Analysis
  • Spinal Muscular Atrophy Types I, II, III
  • Survival Motor Neuron 1
  • Infantile Muscular Atrophy
  • Werdnig-Hoffmann Disease
MMGL Molecular Genetics
Specimen Requirements
Collection Instructions

Collect specimen in a lavender top tube. Send intact specimen within 24 hours if stored at room temperature or within 5 days if stored refrigerated. Include the patient's family history, pedigree, and ethnicity on the test requisition. Obtaining informed consent from the patient prior to genetic testing is strongly recommended. If desired, a UMHS Request and Consent for Genetic Testing form can be obtained from the MMGL Molecular Genetics Laboratory by contacting the MLabs Client Services Center at 800-862-7284 or online at https://mlabs.umich.edu/media/188.

Normal Volume
5 - 10 mL EDTA whole blood
Minimum Volume
2 mL EDTA whole blood
Additional Information

Spinal Muscular Atrophy (SMA) is an autosomal recessive neuromuscular disorder. SMN1 and SMN2 are two highly-similar genes that have a critical role in defining SMA. SMN2 is much less efficient in making the SMN protein; therefore it is the SMN1 gene which is the determinant factor in SMA. Most patients with SMA are homozygous for a deletion or gene conversion of SMN1. The presence of multiple copies of SMN2 in patients homozygous for a deletion or gene conversion of SNM1 can modify the phenotype and lead to less severe disease. By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes medical geneticist interpretation of results billed as a separate additional charge. This test is not available without interpretation.

CPT Code
Fee Code
Pro Fee CPT