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Order Code 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)

Container/Tube:

Preferred: Blood Spot Collection Card

Acceptable: PerkinElmer 226 filter paper, Munktell filter paper, Whatman Protein Saver 903 paper, local newborn screening card, or blood collected in tubes containing ACD or EDTA and then spotted and dried on filter paper.

Specimen Volume: 3 Blood spots

Collection Instructions:

12. 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).


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:

-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) 90 days
  Frozen  90 days
  Ambient  28 days

Reject Due To

Blood spot specimen that shows serum rings or has multiple layers Reject
Insufficient specimen Reject
Specimens known to have been exposed to elevated temperatures above ambient Reject

Reference Values

An interpretive report will be provided.

Method Description

Dried blood spots are processed using 2 analytical protocols with postanalytical integration of all test results.

 

Protocol 1:

A dried blood spot is extracted by the addition of methanol containing known concentrations of isotopically labeled amino acids and acylcarnitines, which are used as internal standards. The extract is derivatized by the addition of 3M hydrochloric acid in n-butanol. From the residual blood spot, a second extraction and derivatization are performed and analyzed concurrently by flow injection tandem mass spectrometry for creatine and creatinine.(Turgeon C, Magera M, Allard P, et al. Combined newborns screening for succinylacetone, amino acids, and acylcarnitines in dried blood spots. Clin Chem. 2008;54[4]:657-664)

 

Protocol 2:

Three 1/8-inch dried blood spots (DBS) are excised from a single specimen. The enzymes are extracted from 2 DBS by incubating the specimens with a mix of substrate and internal standard for acid sphingomyelinase, beta-glucocerebrosidase, alpha-glucosidase, alpha-galactosidase, galactocerebrosidase, alpha-L-iduronidase, and iduronate 2-sulfatase. The sample is then purified by liquid-liquid extraction. The third DBS is extracted with methanol containing d4-C26 lysophosphatidylcholines. The resulting extracts are then combined, evaporated, and reconstituted before analysis by tandem mass spectrometry. (Tortorelli S, Turgeon CT, Gavrilov DK, et al. Simultaneous testing for 6 lysosomal storage disorders and X-adrenoleukodystrophy in dried blood spots by tandem mass spectrometry. Clin Chem. 2016;62[9]:1248-1254)

Day(s) Performed

Monday through Saturday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

83789

Testing Algorithm

If the patient has abnormal newborn screening result for Pompe disease, immediate action should be taken. Refer to the appropriate ACMG Newborn Screening ACT Sheet.(1)

 

For more information see  Newborn Screen Follow-up for Pompe Disease