Hexosaminidase A and Total, Leukocytes/Molecular Reflex
Method Description Describes how the test is performed and provides a method-specific reference
Leukocyte hexosaminidase A and total hexosaminidase are estimated using a semiautomated modification of the method of O'Brien, et al (1970) with further specific recommendations on specimen preparation as outlined by the International Tay-Sachs Disease Testing Quality Control and Data Collection Center.(O'Brien JS, Okada S, Chen A, Fillerup DL: Tay-Sachs disease: detection of heterozygotes and homozygotes by hexosaminidase assay. N Engl J Med 1970;283:15-20)
A non-PCR-based assay using Invader technology available as an ASR (analyte-specific reagent) from Third Wave Technologies (USA) is used to test for the exon 11 (1278insTATC), intron 12 (IVS12[+1]G->C), and exon 7 (G269S) mutations within the alpha-chain of the lysosomal enzyme beta-hexosaminidase A gene. The Invader reaction takes advantage of the specificity of a Cleavase enzyme in recognizing the 3-dimensional structure formed by an "invading" oligonucleotide, a primary oligonucleotide probe with a 5' "flap," and the nucleic acid target of interest. The Invader reaction releases thousands of "flap" sequences per hour that are detected by a FRET (fluorescent resonance energy transfer) cassette. This reaction allows for linear amplification and also reduces the potential for contamination with amplified target sequence that can occur with PCR.(de Arruda M, Lyamichev VI, Eis PS, et al: Invader technology for DNA and RNA analysis: principles and applications. Expert Rev Mol Diagn 2002;2:487-496; Grody WW, Griffin JH, Taylor AK, et al: American College of Medical Genetics consensus statement on factor V Leiden mutation testing. Genet Med 2001;3:139-148)
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.
Monday, Thursday Friday; 8 a.m. (not reported on Saturday or Sunday)
Specimens are only stabilized Monday through Sunday.
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.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
WBC homogenate stored 1 month
Performing Laboratory Location The location of the laboratory that performs the test