Paeds Vivas · clinical-pharmacology-and-therapeutics
Pharmacogenomics and precision therapeutics — branching viva
Branching viva on pharmacogenomics in children: designing a TPMT and NUDT15-guided thiopurine plan, applying the HLA-B star 15 colon 02 screen before carbamazepine in a child of Asian ancestry, and defending the codeine and CYP2D6 ultrarapid-metaboliser reasoning that governs the post-tonsillectomy analgesia decision.
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Opening — the azathioprine start in Crohn disease
Examiner: A ten-year-old is about to start azathioprine for moderate Crohn disease. What tests do you order, and why together? [1]
Candidate (model): Before the first dose I order thiopurine methyltransferase, TPMT, and NUDT15 genotype together, because either gene can cause thiopurine toxicity and their effects are additive. I pair them with a baseline full blood count and liver enzymes so the monitoring curve starts from a known point. The genotype is a once-in-a-lifetime result, so it is recorded in a place the next prescriber finds and flagged on the chart. [1]
References3ShowHide
- [1]Relling MV, Schwab M, Whirl-Carrillo M Clinical Pharmacogenetics Implementation Consortium Guideline for Thiopurine Dosing Based on TPMT and NUDT15 Genotypes: 2018 Update. Clinical pharmacology and therapeutics, 2019.PMID 30447069
- [2]Crews KR, Gaedigk A, Dunnenberger HM Clinical Pharmacogenetics Implementation Consortium guidelines for cytochrome P450 2D6 genotype and codeine therapy: 2014 update. Clinical pharmacology and therapeutics, 2014.PMID 24458010
- [5]Phillips EJ, Sukasem C, Whirl-Carrillo M Clinical Pharmacogenetics Implementation Consortium Guideline for HLA Genotype and Use of Carbamazepine and Oxcarbazepine: 2017 Update. Clinical pharmacology and therapeutics, 2018.PMID 29392710