Mutations analysed according to parenchymal disease subtype are, in IPF group: TP53 (n = 11, 73%), MET (n = 3, 20%), PTEN, SMAD4, FBXW7, STK11, PIK3CA and EGFR amplification (n = 1, 7%); in non-IPF group: TP53 (n = 8, 67%), BRAF (n = 3, 25%), FGFR3 and PIK3CA (n = 2, 17%), STK11, DDR2, MET, KRAS, ERBB4 and CTNNB1 (n = 1, 8%). The gene discussed is ERBB4; the disease is idiopathic pulmonary fibrosis.