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Test ID: PD2T Pompe Disease Second-Tier Newborn Screening, Blood Spot


Necessary Information


1. Birth weight (grams)

2. Time of Birth (24-hour time)

3. Gestational Age (weeks)



Specimen Required


Supplies: Card - Blood Spot Collection (Filter Paper) (T493)

Container/Tube:

Preferred: Blood Spot Collection Card (T493)

Acceptable: Ahlstrom 226 filter paper and Whatman Protein Saver 903 paper

Specimen Volume: 3 blood spots

Collection Instructions:

1. Do not use device or capillary tube containing EDTA to collect specimen.

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

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

4. Do not stack wet specimens.

5. Keep specimen dry.


Forms

Biochemical Genetics Patient Information (T602) in Special Instructions

Useful For

Second-tier testing of newborns with an abnormal screening result for Pompe disease

Method Name

Flow Injection Analysis-Tandem Mass Spectrometry (FIA-MS/MS)

Reporting Name

Pompe Disease 2ND Tier NBS, BS

Specimen Type

Whole blood

Specimen Minimum Volume

Blood Spots: 1

Specimen Stability Information

Specimen Type Temperature Time
Whole blood Refrigerated (preferred) 56 days
  Frozen  56 days
  Ambient  7 days

Clinical Information

Pompe disease, also known as glycogen storage disease type II, is an autosomal recessive disorder caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA; acid maltase) due to mutations in the GAA gene. The estimated incidence is 1 in 40,000 live births. In Pompe disease, glycogen that is taken up by lysosomes during physiologic cell turnover accumulates, causing lysosomal swelling, cell damage, and, eventually, organ dysfunction. This leads to progressive muscle weakness, cardiomyopathy, and, eventually, death. Patients with Pompe disease, especially those with infantile, childhood, and juvenile onset, can have elevations of serum enzymes (such as creatine kinase) secondary to cellular dysfunction.

 

The clinical phenotype of Pompe disease lies on a spectrum, with age of onset dependent on residual enzyme activity. Complete loss of enzyme activity causes onset in infancy leading to death, typically within the first year of life when left untreated. Juvenile and adult-onset forms, as the names suggest, are characterized by later onset and longer survival. Newborn screening can identify patients with all forms of Pompe disease, even before onset of symptoms. Unaffected patients with GAA pseudodeficiency alleles may also be identified by newborn screening. Treatment with enzyme replacement therapy is available, making early diagnosis of Pompe disease desirable, as early initiation of treatment may improve prognosis.

Reference Values

An interpretive report is provided.

Interpretation

An interpretive report is provided.

 

The quantitative measurements of informative metabolites and related ratios are evaluated using the Collaborative Laboratory Integrated Reports (CLIR) system. The report is in text form only, indicating if the applicable ratio is normal or abnormal and whether or not the CLIR postanalytical tool is informative for Pompe disease. Abnormal results are not sufficient to conclusively establish a diagnosis of a particular disease. To verify a preliminary diagnosis, independent biochemical (ie, in vitro enzyme assay) or molecular genetic analyses are required, many of which are offered within Mayo Clinic's Division of Laboratory Genetics and Genomics. Recommendations for additional biochemical testing and confirmatory studies (enzyme assay, molecular analysis) are provided in the interpretative report.

Clinical Reference

Pascual JM, Roe CR: Systemic Metabolic Abnormalities in Adult-onset Acid Maltase Deficiency. JAMA Neurol 2013;70(6):756-763

Day(s) and Time(s) Performed

Monday through Saturday; 4 p.m.

Sunday 1 p.m.

Analytic Time

2 days

Test Classification

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

CPT Code Information

83789

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PD2T Pompe Disease 2ND Tier NBS, BS In Process

 

Result ID Test Result Name Result LOINC Value
48436 Interpretation In Process
48435 Reviewed By In Process
BG700 Birth Weight (grams, XXXX) 8339-4
BG701 Time of Birth (24hr time, XX:XX) 57715-5
BG702 Gestational Age (weeks, XX.X) 76516-4
Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-biochemical