Determination of cross-reactive immunologic material status using leukocytes from patients with Pompe disease
Evaluating the best strategy for enzyme replacement therapy for patients with Pompe disease
This test is used to determine cross-reactive immunological material (CRIM) status in patients with Pompe disease.
CRIM status is important when assessing whether immunosuppression is needed when initiating enzyme replacement therapy for patients with Pompe disease.
For more information see Newborn Screen Follow-up for Pompe Disease
Western Blot
CRIM
Cross-reactive immunologic material
For more information see Newborn Screen Follow-up for Pompe Disease
Whole blood
For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerated within 7 days of collection to be stabilized. Collect specimen Monday through Thursday only and not the day before a holiday. Specimen should be collected and packaged as close to shipping time as possible.
Supplies: Vacutainer 4.0 mL CPT Sodium Citrate Mononuclear Cell Preparation, 4.0 mL (T840)
Container/Tube: Sodium citrate cell preparation tube (CPT blue/black striped top)
Specimen Volume: 4 mL
Collection Instructions:
1. Collect 4 mL blood in CPT mononuclear, sodium citrate CPT tube (blue/black striped top)
2. Mix by inversion 6 to 8 times.
3. Centrifuge at 1800xg for 30 minutes within 2 hours of collection.
4. Send CPT tube on cold packs. Do not aliquot plasma.
1. Biochemical Genetics Patient Information (T602)
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
2 mL
| Gross hemolysis | Reject |
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Refrigerated | 7 days | NaCit BLUBLK CellPrep |
Determination of cross-reactive immunologic material status using leukocytes from patients with Pompe disease
Evaluating the best strategy for enzyme replacement therapy for patients with Pompe disease
For more information see Newborn Screen Follow-up for Pompe Disease
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 alterations in the GAA gene. The estimated incidence is 1 in 40,000 live births. In Pompe disease, glycogen is taken up by lysosomes during physiologic cell turnover and accumulates, causing lysosomal swelling and cell damage, which results in organ dysfunction. Symptoms include progressive muscle weakness, cardiomyopathy, and, eventually, death if untreated.
Clinically, Pompe disease is categorized into infantile and late-onset forms based on age of onset, organ involvement, and rate of progression. The infantile form (or classic Pompe disease) is the most severe variant and is characterized by early onset and rapid progression of cardiac, liver, and muscle problems resulting in death within the first year of life. The infantile variant of Pompe disease has a similar age of onset but a milder clinical presentation. Late-onset Pompe disease can present with muscle weakness, cardiomyopathy, and/or respiratory dysfunction in childhood or later, including advanced adulthood. The rate of progression and severity of symptoms is variable, particularly in the late-onset forms.
Treatment with enzyme replacement therapy (ERT) is available, making early diagnosis of Pompe disease desirable because early initiation of treatment improves the prognosis. Treatment with ERT can prolong survival in patients with infantile onset Pompe disease; however, the effectiveness of treatment is impacted by the presence or absence of cross-reactive immunologic material (CRIM) to the GAA enzyme. Patients who are CRIM-negative are more likely to develop antibodies against recombinant human GAA than patients who are CRIM-positive, thereby decreasing the effectiveness of treatment. Strategies to decrease the immune response to ERT, such as immunosuppression, rely on determination of CRIM status.
Molecular analysis of the GAA gene can determine CRIM status in over 90% of patients with Pompe disease (GAAZ / Pompe Disease, Full Gene Analysis, Varies). However, for those who have GAA variants not classified as either CRIM-negative or -positive, CRIM testing in leukocytes can determine final CRIM status. Therefore, CRIM testing is useful for either confirmation of CRIM status determined by molecular testing or determination of CRIM status if the genotype is not informative.
An interpretive report will be provided
The presence of cross-reactive immunologic material (CRIM) indicates a decreased likelihood that a patient affected with Pompe disease (acid alpha-glucosidase: GAA deficiency) will develop an immune response to enzyme replacement therapy with recombinant GAA.
The absence of CRIM in untreated patients with Pompe disease indicates a need to consider additional measures to prevent an immune response to the administration of enzyme replacement therapy with recombinant GAA.
The test by itself is not diagnostic of Pompe disease, and results need to be interpreted in light of the clinical presentation and other laboratory tests, such as creatine kinase, acid alpha-glucosidase (GAA) activity, and GAA genotype.
Use of sodium heparin tubes for collection may cause assay interference and should not be used.
1. Kishnani PS, Goldenberg PC, DeArmey SL, et al: Cross-reactive immunologic material status affects treatment outcomes in Pompe disease infants. Mol Genet Metab. 2010 Jan;99(1):26-33
2. Bali DS, Goldstein JL, Rehder C, et al: Clinical laboratory experience of blood CRIM testing in infantile Pompe disease. Mol Genet Metab Rep. 2015 Dec 1;5:76-79. doi: 10.1016/j.ymgmr.2015.10.012
3. Reuser AJ, Hirschhorn R, Kroos MA: Pompe disease: Glycogen storage disease type II, acid alpha-glucosidase (acid maltase) deficiency. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed October 11, 2022. Available at https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225890450
4. Leslie N, Bailey L: Pompe disease. In: Adam MP, Everman DB, Mirzaa GM, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2007. Updated May 11, 2017. Accessed October 11, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK1261/
Western blot analysis is performed using peripheral blood mononuclear cells. Lysed cells are quantitated for protein, separated by gel electrophoresis, and transferred to a polyvinylidene difluoride (PVDF) membrane. The PVDF membrane is then incubated with antibodies specific to acid alpha-glucosidase (GAA, the protein of interest) and b-actin (used as an internal quality control protein). A chemiluminescent substrate is added to the membrane and the emitted light signal is captured by digital imaging. If specific bands are present, the patient is determined to be cross-reactive immunologic material (CRIM)-positive while the absence of these bands indicates a CRIM-negative result.(Wang Z, Okamoto P, Keutzer J: A new assay for fast, reliable CRIM status determination in infantile-onset Pompe disease. Mol Genet Metab. 2014 Feb;111[2]:92-100)
Once per month
For patients 6 months of age or younger at collection, sample will be run as soon as received in lab. For patients older than 6 months of age at collection, samples will be batched and ran once per month.
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.
84182
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| PDCRW | Pompe Disease CRIM Status, WBC | 99308-9 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 606127 | GAA CRIM status | In Process |
| 606128 | Interpretation | 59462-2 |
| 606129 | Reviewed By | 18771-6 |