Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

GAABS
89210
pseudocholinesterase activity in serum and red cell AChE are inhibited by these insecticides, but they are
dramatically different vis-a-vis the temporal aspect of the exposure. The half-life of the pseudo-enzyme in
serum is about 8 days, and the "true" cholinesterase (AChE) of red cells is over 3 months (determined by
erythropoietic activity). Recent exposure up to several weeks is determined by assay of the
pseudo-enzyme and months after exposure by measurement of the red cell enzyme. The effect of the
specific insecticides may be important to know prior to testing.
Useful For: Detecting effects of remote (months) past exposure to cholinesterase inhibitors
(organophosphate insecticide poisoning)
Interpretation: Activities less than normal are suspect for exposure to certain insecticides.
Reference Values:
31.2-61.3 U/g of hemoglobin
Clinical References: 1. Robinson DG, Trites DG, Banister EW: Physiological effects of work
stress and pesticide exposure in tree planting by British Columbia silviculture workers. Ergonomics
1993;36:951-961 2. Fuortes LJ, Ayebo AD, Kross BC: Cholinesterase-inhibiting insecticide toxicity.
Am Fam Phys 1993;47:1613-1620
Acid Alpha-Glucosidase, Blood Spot
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 alpha-glucosidase (GAA)
leading to an accumulation of glycogen in the lysosome causing swelling, cell damage, and progressive
organ dysfunction. Pompe disease is caused by mutations in the GAA gene, and it is characterized by
muscle hypotonia, weakness, cardiomyopathy, and eventually death due to either cardiorespiratory or
respiratory failure. The clinical phenotype, in general, appears to be dependent on residual enzyme
activity, with complete loss of activity causing onset in infancy leading to death, typically within the
first year of life. Juvenile and adult-onset forms are characterized by later onset and longer survival.
Treatment by enzyme replacement therapy, recently available, makes early diagnosis of Pompe disease
desirable, as early initiation of treatment may improve the prognosis. The estimated incidence is 1 in
40,000 live births. Since Pompe disease is considered a rare condition that progresses rapidly in infancy,
the disease, in particular the juvenile and adult-onset forms, is often considered late, if at all, during the
evaluation of patients presenting with muscle hypotonia, weakness, and/or cardiomyopathy. Testing
traditionally required a skin or muscle biopsy to establish cultures for enzyme testing. More recently,
molecular genetic testing of the GAA gene (GAAMS/89898 Pompe Disease, Full Gene Sequencing)
became clinically available. Determination of the enzyme assay in dried blood spot specimens can be
performed in a timely fashion and provide better guidance in the decision to submit samples for further
confirmatory testing by molecular genetic analysis (GAAMS/89898 Pompe Disease, Full Gene
Sequencing).
Useful For: Evaluation of patients of any age with a clinical presentation suggestive of Pompe
disease (muscle hypotonia, weakness, and/or cardiomyopathy)
Interpretation: Normal results (>7.4 pmol/dried blood spot punch/hour) in properly submitted
specimens are not consistent with classic Pompe disease. Affected individuals typically show