High prevalence of IDH mutation in myeloid neoplasm with RA. (A) In all, 9.5% of cases with MDS had AIRD compared with only 4.7% of cases with AML (P = .003). (B) Inflammatory arthritis is the most prevalent AIRD in the MN-AIRD cohort. Inflammatory arthritis includes RA plus peripheral spondyloarthropathy. (C) Volcano plot comparing the blood counts, bone marrow blast, cytogenetic changes, and somatic mutation profile of MN-AIRD vs MN without AIRD. (D) Enrichment of IDH mutations in MN-AIRD compared with MN without AIRD, especially MDS-AIRD compared with MDS without AIRD. (E) Unexpected enrichment of IDH mutation observed in male cases with MN-AIRD but not in female cases with MN-AIRD. (F) High burden of IDH mutation in MN with RA compared with MN with other subtype of AIRD. (G) Frequency of IDH mutation according to subtype of AIRD in MN. (H) Strikingly high frequency of IDH mutation in seronegative RA compared with seropositive RA. (I) Majority of seronegative RA harbors IDH1 mutation, in contrast to IDH2 mutation in other MN-AIRDs. (J) In an independent validation cohort, one-third of patients with IDH^mut CMML have AIRD. The χ² test was used to determine associations between categorical variables. CTD, connective tissue diseases.