Whilst changes in the composition and architecture are the major collagen alterations in lung tumors, mutations in collagen type V alpha 2 chain (COL5A2) and collagen type II alpha I chain (COL2A1) genes have also been detected in subclonal secondary lung tumors following genomic doubling events in both adenocarcinoma and squamous carcinoma (44). The gene discussed is COL5A2; the disease is adenocarcinoma.