MRI of the ankle and sacroiliac joints in Twin A and Twin B. (A) Sagittal plain T2-weighted images of Twin A displaying tendinopathy of the left Achilles tendon (white arrow). (B) STIR images of Twin A displaying the sacroiliac bone marrow edema (white arrow). (C) Sagittal plain T2-weighted images of Twin B displaying synovial proliferation and joint effusion (white arrow). (D) STIR images of Twin B displaying bilateral sacroiliac bone marrow edema (white arrows). MRI: magnetic resonance imaging, STIR: short tau inversion recovery.|@|~(^,^)~|@|Cell clusters identified by single-cell RNA sequencing analysis. (A) Identification of 14 clusters in pooled peripheral blood mononuclear cells from twins who developed spondyloarthritis after COVID-19 and one patient with typical radiographic axial spondyloarthritis. (B) Difference in frequency of cell population is displayed in bar plots. COVID-19: coronavirus disease 2019, UMAP: Uniform Manifold Approximation and Projetion.|@|~(^,^)~|@|The differentially expressed genes from single-cell RNA sequencing analysis. (A) The mRNA expression of ribosomal protein S26 (RPS26) is systematically down-regulated in most subsets of spondyloarthritis (SpA) after coronavirus disease 2019 (COVID-19) compared to that in typical axial spondyloarthritis. (B) The expression of small nucleolar RNA host gene 5 (SNHG5) is consistently upregulated in most subsets of SpA after COVID-19 compared to that in typical axial spondyloarthritis.|@|~(^,^)~|@|Continued.

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