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Test Code Billings Clinic: 4835 Prometheus: 3300 TPMT Genetics

Performing Laboratory

Prometheus Laboratories, Inc.

Useful For

Prometheus TPMT Genetics assessment is an analysis to determine an ability to produce thiopurine methyltransferase (TPMT) activity. It is a method to identify patients at risk for acute toxicity from 6-MP or azathioprine. This profile provides a breakdown of a patient’s genetics. The distribution of TPMT activity is trimodal; homozygous normal (89%), heterozygous (11%), and homozygous recessive (0.3%). Approximately 1 in 1,213 individuals may have a low TPMT enzyme activity (homozygous low) resulting from known and theoretical mutations that are not included in this panel.

Methodology

Polymerase Chain Reaction (PCR)

Specimen Requirements

  • Draw blood in a lavender-top (EDTA) tube(s)
  • Send 5 mL of unprocessed EDTA whole blood refrigerated.
  • Do not centrifuge.
  • Forward unprocessed whole blood promptly.
  • Samples <10 days old can be sent ambient.
  • Samples >30 days old must be sent refrigerated.

Reference Values

Reference values are included with patient’s report.

Day(s) Test Set Up

Monday through Friday

Test Classification and CPT Coding

83891- isolation

83896 x 6 - nucleic acid probe, each

83898 x 3 - amplification, target, each nucleic acid sequence

83912 - interpretation and report