The Clinical Pharmacogenetics Implementation Consortium (CPIC) TPMT/NUDT15 Pharmacogene Curation Expert Panel (PCEP) conducted a comprehensive review of clinical, laboratory, and computational evidence to determine the clinical function assignments for TPMT and NUDT15 star alleles. These genes are critical for the metabolism of thiopurines, which are widely used in the treatment of cancer and autoimmune disorders. Standardized allele function assignment is essential for predicting metabolizer phenotypes and pharmacogenetics‐guided thiopurine dosing. The work presented here includes the first designation of decreased function alleles for both TPMT and NUDT15, reflecting new clinical data that demonstrate partial loss of enzymatic activity and reduced dose tolerance. The panel also reclassified several alleles previously assigned uncertain or unknown function. The functional assignments were informed by a standardized framework incorporating clinical data, such as thiopurine tolerance and toxicity, as well as in vitro protein activity, ex vivo enzymatic measurements, and in silico variant effect prediction tools. These updates enhance the precision of genotype‐to‐phenotype mapping and support more personalized thiopurine therapy across diverse patient populations.
Bailey M. Tibben, Maud Maillard, Victoria M. Pratt et al.· Clinical pharmacology and th...· 0 citations
Histone post-translational modifications (PTMs) are key regulators of chromatin architecture and gene expression. Although mass spectrometry (MS)-based data-independent acquisition (DIA) pipelines for histone PTM quantification are available, multiplexed targeted assays remain underdeveloped. Here, we present a derivatization-free parallel reaction monitoring (PRM) workflow for robust, quantitative, and site-specific analysis of major histone H3 and H4 PTMs. We employed highly efficient ArgC digestion to generate peptides of optimal length for liquid chromatography-tandem mass spectrometry (LC–MS/MS) while preserving endogenous PTMs, and we optimized chromatographic conditions to achieve isobaric separation and stable retention times. Co-eluting isobaric PTM species were confidently distinguished using site-specific fragment ions. The resulting PRM method enabled sensitive and reproducible detection of histone PTM isoforms across diverse biological systems. To illustrate its utility, we analyzed PTM dynamics in cells expressing histone H3.3 lysine-to-methionine substitutions and in cells treated with the histone deacetylase inhibitor entinostat, yielding results that correlated strongly with antibody-based readouts. This PRM platform provides a complementary, targeted approach to current chemical derivatization–based methods, enabling reliable validation of selected histone PTMs.
Hyoungjoo Lee, Ashley K. Wiseman, Bailey M. Tibben et al.· ACS Omega· 0 citations
