Diagnosis

Establish or confirm diagnosis

Diagnosis of Pompe disease

The specimens are incubated with a mix of substrate and internal standard for acid alpha-glucosidase and alpha-galactosidase (GLA). The reaction is then stopped using acetonitrile, centrifuged, and a portion of the supernatant is prepared for analysis by liquid chromatography-tandem mass spectrometry. GLA is included to verify sample integrity.(Unpublished Mayo method)

Tests performed
Entire test performed in-house

Recovery was used to assess accuracy; the acceptance criteria were met with coefficients of linear regression (R2) of 0.9998 and slope of 0.9979 for GAA. Intra assay precision was performed at 3 levels: CV results ranged from 3%-6% (N=20 each). Inter assay precision was performed at 3 levels: CV results … Recovery was used to assess accuracy; the acceptance criteria were met with coefficients of linear regression (R2) of 0.9998 and slope of 0.9979 for GAA. Intra assay precision was performed at 3 levels: CV results ranged from 3%-6% (N=20 each). Inter assay precision was performed at 3 levels: CV results ranged from 5%-7% (N=20 each). The analytical measurement range is 0.002-123.825 nmol/h/mg protein. View more

Pseudodeficiency results in low measured acid alpha-glucosidase activity, but it is not consistent with Pompe disease. Enzyme levels may be normal in individuals receiving enzyme replacement therapy.

Is proficiency testing performed for this test? Help
Yes

Method used for proficiency testing: Help
Intra-Laboratory

Description of PT method: Help
Intra-laboratory alternative assessment of performance through quality control or patient blind testing

Description of internal test validation method: Help
This test was laboratory developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements.