Risk interpretation based on Coriell's TPMT Activity Genotype Translation Version 1 (December 2010).
Interpretation
Based on this individual’s Combined Genetic Result TPMT*3A/*3C, low/absent TPMT activity is expected.
Individuals with low/absent TPMT activity are at an increased risk of developing severe, life-threatening bone marrow suppression when taking a standard dose of a thiopurine drug. A reduced dosage or alternate immunosuppressant therapy should be considered.
Test Limitations
DNA-based testing is highly accurate, however there are many sources of potential
error including: mis-identification of samples, rare technical errors, trace contamination
of PCR reactions, and rare genetic variants that interfere with analysis. There
may be other variants in the TPMT gene that are not included in this test, that
influence the response to thiopurine drugs. This test or one or more of its components
was developed and its performance characteristics determined by the Coriell Institute
for Medical Research. It has not been approved by the Food and Drug Administration
(FDA). The FDA has determined that such approval is not necessary. The Coriell Institute
is regulated under the Clinical Laboratory Improvement Amendments (CLIA) of 1988
as qualified to perform high-complexity testing.
Test Methodology
Saliva samples were collected using Oragene DNA Collection Kits (DNA Genotek) and
DNA was extracted manually according to the manufacturer’s instructions or automatically
using a DNAdvance Kit (Agencourt). Purified DNA was quantified using UV absorbance
at 260 nm. One microgram of the resulting DNA from each sample was used as template
in the Affymetrix DMET Plus GeneChip assay. Data analysis was performed using Affymetrix
DMET Console software.