NTN4 and idiopathic pulmonary fibrosis: Finally, the signal at 12q23.1 (rs7957346) had the highest probability of colocalisation for expression of Netrin 4 (NTN4) in lung tissue (posterior probability = 0.649) and had previously been associated with lung function with the IPF risk increasing allele (A) associated with decreased lung function (p=7.8×10−45).