Sorted By Test Name - Mayo Medical Laboratories

AGA
8785
disease. In female patients, normal results (> or =2.8 nmol/mL/hour) in properly submitted specimens are
typically not consistent with carrier status for Fabry disease; however, enzyme analysis, in general, is not
sufficiently sensitive to detect all carriers. Because a carrier range has not been established in females,
molecular genetic analysis of the GLA gene (FABMS/88264 Fabry Disease, Full Gene Analysis) should
be considered when alpha-galactosidase A activity is or =1.2 nmol/mL/h
Females: > or =2.8 nmol/mL/h
An interpretive report will be provided.
Clinical References: 1. Chamoles NA, Blanco M, Gaggioli D: Fabry disease: enzymatic diagnosis
in dried blood spots on filter paper. Clin Chim Acta 2001;308:195-196 2. De Schoenmakere G, Poppe B,
Wuyts B, et al: Two-tier approach for the detection of alpha-galactosidase A deficiency in kidney
transplant recipients. Nephrol Dial Transplant 2008;23:4044-4048 3. Spada M, Pagliardini S, Yasuda M,
et al: High incidence of later-onset Fabry disease revealed by newborn screening. Am J Hum Genet
2006;79:31-40 4. Mehta A, Hughes DA: Fabry disease. GeneReviews. Edited by RA Pagon, TD Bird, CR
Dolan, et al. University of Washington, Seattle. Last updated March 2011
Alpha-Galactosidase, Leukocytes
Clinical Information: Fabry disease is an X-linked recessive lysosomal storage disorder resulting
from deficient activity of the enzyme alpha-galactosidase A (alpha-Gal A) and the subsequent deposition
of glycosylsphingolipids in tissues throughout the body, in particular, the kidney, heart, and brain. More
than 150 mutations in the GLA gene have been identified in individuals diagnosed with Fabry disease.
Severity and onset of symptoms are dependent on the amount of residual enzyme activity. The classic
form of Fabry disease occurs in males with less than 1% alpha-Gal A activity. Symptoms usually appear
in childhood or adolescence and can include acroparesthesias (pain crises in the extremities), multiple
angiokeratomas, reduced or absent sweating, and corneal opacity. In addition, progressive renal
involvement leading to end-stage renal disease typically occurs in adulthood followed by cardiovascular
and cerebrovascular disease. The estimated incidence is 1 in 40,000 males. Males with residual alpha-Gal
A activity may present with either of 2 variant forms of Fabry disease (renal or cardiac) with onset of
symptoms later in life. Individuals with the renal variant typically present in the third decade with the
development of renal insufficiency and, ultimately, end-stage renal disease. These individuals may or may
not share other symptoms with the classic form of Fabry disease. Individuals with the cardiac variant are
often asymptomatic until they present with cardiac findings such as cardiomyopathy, mitral insufficiency,
or conduction abnormalities in the fourth decade. The cardiac variant is not associated with renal failure.
Variant forms of Fabry disease may be underdiagnosed. Females who are carriers of Fabry disease can
have clinical presentations ranging from asymptomatic to severely affected and may have alpha-Gal A
activity in the normal range; therefore, additional studies including molecular genetic analysis of the GLA
gene (FABMS/88264 Fabry Disease, Full Gene Analysis) are recommended to detect carriers. Reduced or
absent alpha-Gal A in blood spots, leukocytes (AGA/8785 Alpha-Galactosidase, Leukocytes), or serum
(AGAS/8784 Alpha-Galactosidase, Serum) can indicate a diagnosis of classic or variant Fabry disease.
Molecular sequence analysis of the GLA gene (FABMS/88264 Fabry Disease, Full Gene Analysis) allows
for detection of the disease-causing mutation in affected patients and carrier detection in females. See
Fabry Disease: Newborn Screen-Positive Follow-up algorithm and Fabry Disease Testing Algorithm in
Special Instructions.
Useful For: Diagnosis of Fabry disease in males Verifying abnormal serum alpha-galactosidase results
in males with a clinical presentation suggestive of Fabry disease
Interpretation: Deficiency of alpha-galactosidase A (alpha-Gal A) is diagnostic for Fabry disease in
males. Carrier females may have alpha-Gal A results within the normal range. See Fabry Disease:
Newborn Screen-Positive Follow-up algorithm and Fabry Disease Testing Algorithm in Special
Instructions.
Reference Values:
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