SFTPC and idiopathic pulmonary fibrosis: Genes encoding for surfactant protein C (SF-C) such as SFTPC have also been implicated in the diagnosis of FIP where a genetic study demonstrated, in a family of five generations, that individuals who were heterozygous for the mutation had biopsy changes consistent with usual interstitial pneumonitis (UIP) or non-specific interstitial pneumonitis (NSIP) [19].