a, Schematic of human chromosome 17, highlighting band 17p13.3, which is deleted in MDS. Encoded genes, including minimal critical MDS deletion are listed on the right. b, Schematic of chr17 status in wild type (WT), MDS patients. c, List of fibroblast lines used in this study. d, e, RT-qPCR for PAFAH1B1 (d) and YWHAE (e) mRNA levels in fibroblasts. f, Images of WT, MDS1r(17) and MDS2 iPSCs. g, Western blot for pluripotency markers in fibroblasts and two iPSC clones. h, Examples of metaphase spreads with or without the ring chromosome. i, Percentage of mitotic cells with or without the ring chromosome in fibroblasts or MDS1r(17) iPSC clones.