RTEL1 and idiopathic pulmonary fibrosis: Exome sequencingalso made it possible to identify rarer forms of familial IPFcaused by mutations in the helicase gene that regulatestelomere elongation (RTEL1: c.602delG, c.1451C>T,c.1940C>T, c.2005C>T, c.3371A>C) and in the deadenylationnuclease gene (PARN: IVS4-2a>g, c.529C>T, c.563_564insT,c.751delA, IVS16+1g>a, c.1262A>G) (Stuart et al., 2015).Cases of familial IPF caused by a mutation in exon 5(+128T>A) in the SFTPC surfactant protein gene are alsodescribed (Thomas et al., 2002).