Identification of rare defective allelic variants in cases of thiopurine S-methyltransferase deficient activity.

To assess rare variants in patients carrying a deficient phenotype not predicted by the four more frequent genotypes and ). Next-generation sequencing of in 39 patients with a discordant genotype. None of the variants identified explained the discordances assuming that they are of uncertain significance according to the Clinical Pharmacogenetics Implementation Consortium classification.