HHIP and chronic obstructive pulmonary disease: For example, two SNPs (rs1828591 and rs13118928) near the Hedgehog-interacting protein (HIP) gene, which is involved in early lung development and response to injuries, were significantly related to COPD development (OR 0.80, 95% CI 0.72–0.91), and this correlation was directly linked with the number of cigarettes smoked in a lifetime [19].