SFTPC and TNF receptor 1-associated periodic fever syndrome: On the other hand, the association of surfactant protein (SFTP)-C (SFTPC), SFTPA2, Telomerase Reverse Transcriptase (TERT), and Telomerase RNA (TERC) mutations with familial pulmonary fibrosis (FPF) demonstrate that a single variation may be the cause of the disease.