Amyloidosis, Transthyretin-Associated Familial, Reflex, Blood
Method Description Describes how the test is performed and provides a method-specific reference
Familial Amyloidosis, Mass Spectrometry (MS):
Transthyretin (TTR) is purified from plasma using affinity chromatography. The chromatography is done using an antihuman-TTR antibody that has been coupled to POROS-aldehyde media. Plasma is reduced with 12.5 mM dithiothreitol (DTT) to simplify the mass spectra by removing Cys10 adducted species. The plasma:DTT solution is then injected onto the affinity column, which sequesters TTR using pH 7.4 phosphate buffer saline. TTR is then eluted from the affinity column with pH 2.5 100 mM glycine:2% acetic acid buffer and concentrated on a C4 column, which is then washed with acetic acid:methanol:water (1:2:97) to remove excess phosphate and other buffer components that suppress MS response. TTR is then eluted from the C4 column and introduced to the MS using methanol:water:glacial acetic acid:TFA (94.5:5:0.5:0.04). The acquired ion spectra are deconvoluted and reviewed for TTR variants. After deconvolution, normal patients present with a single peak corresponding to wild-type (wt) TTR, which serves as a reference. When positive, amyloid patients are typically heterozygous and are detected by the presence of 2 peaks (ie, wt TTR and mutant TTR) differing in mass.(Bergen HR 3rd, Zeldenrust SR, Butz ML, et al: Identification of transthyretin variants by sequential proteomic and genomic analysis. Clin Chem 2004 Sep;50:1544-1552)
Familial Amyloidosis, DNA Sequence:
All 4 exons of the TTR gene are amplified by PCR and then subjected to direct DNA sequence analysis.(Bergen RH 3rd, Zeldenrust SR, Butz ML, et al: Identification of transthyretin variants by sequential proteomic and genomic analysis. Clin Chem 2004;50:1544-1552)
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; 8 a.m.
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
Performing Laboratory Location The location of the laboratory that performs the test