HYDIN and chronic obstructive pulmonary disease: The results showed that hsa_circ_006155, hsa_circ_031080, hsa_circ_041434, MYZAP, NRCAM and SHE were increased, whereas hsa_circ_007446, hsa_circ_019015, hsa_circ_038146, HYDIN, MUC19, and RNF17 were decreased in COPD patients versus normal control samples.