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

Ordering Guidance

Due to reference range differences, this is the appropriate test for patients less than or equal to 6 weeks of age. For patients greater than 6 weeks of age, order PDBS / Pompe Disease, 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)


Preferred: Blood Spot Collection Card

Acceptable: PerkinElmer 226 (formerly Ahlstrom 226) filter paper, Munktell filter paper, Whatman Protein Saver 903 paper, or blood collected in tubes containing ACD, EDTA, or heparin and then spotted and dried on filter paper.

Specimen Volume: 3 blood spots

Collection Instructions:

1. Completely fill at least 3 circles on the filter paper card (approximately 100 microliters blood per circle).

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.

Additional Information:

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

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

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


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. Biochemical Genetics Patient Information (T602)

3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.

Useful For

Second-tier testing of newborns with an abnormal primary screening result for Pompe disease (decreased acid alpha-glucosidase enzyme activity)


Follow-up testing for evaluation of an abnormal newborn 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

1 Blood spot

Specimen Stability Information

Specimen Type Temperature Time Special Container
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 variants 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 elevated serum enzymes (such as creatine kinase) secondary to cellular dysfunction.


The clinical phenotype of Pompe disease lies on a spectrum, with differing clinical phenotypes dependent on age of onset and 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. All disease variants are eventually associated with progressive muscle weakness and respiratory insufficiency. Cardiomyopathy is associated almost exclusively with the infantile form. Treatment with enzyme replacement therapy is available, making early diagnosis of Pompe disease desirable, as early initiation of treatment may improve prognosis. Newborn screening can identify patients with all forms of Pompe disease, even before onset of symptoms. Newborn screening may also identify unaffected patients with GAA pseudodeficiency alleles and carriers.


The ratio calculated using the creatine:creatinine ratio as the numerator and the activity of GAA as the denominator can differentiate true cases of infantile and late-onset Pompe disease from false-positive cases, such as carriers and pseudodeficiency of GAA enzyme. When applied to the newborn screening setting, this second-tier testing can provide results in a timely fashion and provide guidance in the decision to submit samples for additional confirmatory testing by molecular genetic analysis (GAAZ / Pompe Disease, Full Gene Analysis, Varies).

Reference Values

An interpretive report will be provided.


An interpretive report will be 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 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 Laboratories. Recommendations for additional biochemical testing and confirmatory studies (enzyme assay, molecular analysis) are provided in the interpretative report.

Clinical Reference

1. Pascual JM, Roe CR: Systemic metabolic abnormalities in adult-onset acid maltase deficiency: beyond muscle glycogen accumulation. JAMA Neurol. 2013 Jun;70(6):756-763

2. Tortorelli S, Eckerman JS, Orsini JJ, et al: Moonlighting newborn screening markers: The incidental discovery of a second-tier test for Pompe disease. Genet Med. 2018 Aug;20(8):840-846. doi: 10.1038/gim.2017.190

3. Minter Baerg MM, Stoway SD, Hart J, et al: Precision newborn screening for lysosomal disorders. Genet Med. 2018 Aug;20(8):847-854. doi: 10.1038/gim.2017.194

4. Ames EG, Fisher R, Kleyn M, Ahmad A: Current practices for U.S. newborn screening of Pompe Disease and MPSI. Int J Neonatal Screen. 2020 Sep 2;6(3):72. doi: 10.3390/ijns6030072

Day(s) Performed

Monday through Sunday

Report Available

2 to 3 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 US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
PD2T Pompe Disease 2ND Tier NBS, BS 63416-2


Result ID Test Result Name Result LOINC Value
48436 Interpretation 63416-2
48435 Reviewed By 18771-6
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 Clinic Laboratories | Genetics and Pharmacogenomics Catalog Additional Information: