Prevalence of polymorphisms in thiopurine metabolism and association with adverse outcomes: a South Asian region-specific systematic review and meta-analysis.

: Prevalence and impact of thiopurine S-methyltransferase () and Nudix hydrolase () minor allele frequencies in South Asian population is unclear.: We searched PubMed and Embase with keywords- and combined with South Asian countries. We included studies reporting frequency of and polymorphisms. We estimated the pooled prevalence of and polymorphisms and their impact on pooled odds ratio of adverse events with thiopurines.: We included 26 studies in our analysis. The pooled prevalence of and polymorphisms was 16.5% (95% CI: 13.09-20.58) and 4.57% (95% CI: 3.66-5.68), respectively. In patients with adverse effects, the pooled prevalence of and polymorphism was 49.51% (95% C.I. 21.69-77.64) and 9.47% (95% C.I. 5.39-16.11), respectively. The odds ratio (OR) of adverse events with presence of polymorphisms was 3.65 (95% C.I., 1.43-9.28). The pooled OR for adverse events in presence of polymorphism was 12.63 (95% C.I., 3.68-43.26).: were reported more frequently than the polymorphisms in South Asian population and were more frequently associated with adverse events. These findings may have implications for preemptive testing amongst South Asian population and immigrants prior to starting thiopurines.