Test Catalog

Test ID: G6SW    
N-Acetylgalactosamine-6-Sulfatase, Leukocytes

Method Description Describes how the test is performed and provides a method-specific reference

Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) results from a deficiency of the N-acetylgalactosamine-6-sulfate sulfatase enzyme. This enzyme hydrolyzes a sulfate group from the 6 position of galactose at the nonreducing terminus of the mucopolysaccharides, keratin sulfate and chondroitin-6 sulfate. In this procedure, 4- methylumbelliferyl (MU)-beta-D-galactoside-6-sulfate is used as the substrate. The enzyme will cleave the 6-sulfate from the galactose residue and a second incubation with excess beta-galactosidase will cleave the 4MU, which is measured fluorometrically and calculated against a calibration of 4MU.(Package insert: Laboratory protocol for enzyme analysis for Morquio A disease [MPS IV A]. Moscerdam Substrates;  van Diggelen OP, Zhao H, Kleijer WJ, et al: A fluorimetric enzyme assay for the diagnosis of Morquio disease type A. Clin Chim Acta. 1990;187:131-140; Cowan T, Pasquali M: Laboratory Investigations of Inborn Errors of Metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. 2017:1139-1158)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.


Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

30 days

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Clinic Laboratories until the release of the test result

45 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

WBC homogenate: 1 month

Performing Laboratory Location Indicates the location of the laboratory that performs the test