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Objectives: This study aimed to evaluate the clinical characteristics and clinical course of Asian elderly-onset Crohn’s disease (EOCD) patients in a large well-defined cohort of South Korean IBD patients. Materials and methods: From the Asan inflammatory bowel disease registry, we identified 29 EOCD patients (diagnosed with CD in age of 60 years or over) out of 2989 CD patients (1.0%). After excluding two patients with unclear data, 27 EOCD were matched with 108 young-onset CD (YOCD) and 108 middle age-onset CD (MOCD) for the interval from symptom onset to diagnosis (±3 years) and follow-up duration (±3 years). Results: Females were predominant in the EOCD group (59.3%) compared to MOCD (31.5%) and YOCD (29.6%) groups (p = .012). In EOCD group, terminal ileal location was the most common (63.0%) at diagnosis, whereas ileocolonic location in other groups (57.4% in MOCD and 78.7% in YOCD, respectively) (p < .001). Patients with perianal fistula at CD diagnosis were less common (14.8% in EOCD vs. 28.7% in MOCD vs. 49.1% in YOCD, p < .001). During follow-up, thiopurines were used less frequently in the EOCD group (48.1% in EOCD vs. 87.0% in MOCD vs. 89.8% in YOCD, p < .001), but the risk for intestinal resection was comparable among three groups (p = .583). Conclusions: EOCD may have a better clinical course than MOCD and YOCD, as demonstrated by the similar risk for intestinal resection despite the less frequent use of thiopurines. [ABSTRACT FROM AUTHOR]

BackgroundThe impact of genetic variation in thethiopurine S-methyltransferase (TPMT)gene on thiopurine-induced leukopenia has been well demonstrated. Although xanthine dehydrogenase (XDH)is the second major contributor to azathioprine breakdown, polymorphisms inXDHhave rarely been studied in IBD patients. We aim to access association betweenXDHvariants and thiopurine-induced leukopenia by gene–gene interaction in a Crohn’s disease (CD) population.StudyA total of 964 CD patients treated with thiopurines were recruited from a tertiary referral center. The association between fourXDHvariants (p.Gly172Arg, p.Asn1109Thr, p.Arg149Cys, and p.Thr910Lys) and thiopurine-induced leukopenia was analyzed in cases with early leukopenia (n = 66), late leukopenia (n = 264), and in controls without leukopenia (n = 632). Three non-synonymous SNPs, which we previously reported association with thiopurine-induced leukopenia,NUDT15(p.Arg139Cys),SUCLA2(p.Ser199Thr), andTPMT *3Cwere selected for epistasis analysis with theXDHvariants.ResultsThere was no significant association for two variants ofXDHand thiopurine-induced leukopenia. In the epistasis analysis, onlyXDH(p.Asn1109Thr) *SUCLA2(p.Ser199Thr) showed a statistically significant association with early leukopenia [odds ratio (OR) = 0.16;p = 0.03]. After genotype stratification, a positive association on the background ofSUCLA2wild-type (199Ser) between theXDH(p.Asn1109Thr) and early leukopenia (OR = 4.39;p = 0.01) was detected.ConclusionGenes associated with thiopurine-induced leukopenia can act in a complex interactive manner. Further studies are warranted to explore the mechanisms underlying the effects of the combination ofXDH(p.Asn1109Thr) andSUCLA2(199Ser) on thiopurine-induced leukopenia. [ABSTRACT FROM PUBLISHER]