DNA analyses of two siblings who died of IPF revealed significantly shortened peripheral blood telomeres, undetectable alveolar epithelial telomeres, and a shared new A-to-G transition near the TERC-binding domain in DKC1; this domain would encode an amino acid substitution for Thr405Ala, a mutation that destabilizes TERC and impairs telomerase function 71. This evidence concerns the gene TERC and idiopathic pulmonary fibrosis.