Rare variants are identified in about 30% of patients with familial IPF and mainly encode proteins involved in either telomere maintenance such as TERT, TERC (telomerase RNA component), TINF2 (TERF1 interacting nuclear factor 2), DKC1 (dyskerin), RTEL1, PARN (poly(A)-specific ribonuclease), NAF1 (nuclear assembly factor 1 ribonucleoprotein) [16,17] or surfactant production such as SFPTA1, SFPTA2, SFPTC (surfactant protein A1, A2, C), and ABCA3 (ATP binding cassette subfamily A member 3) [18,19,20]. Here, PARN is linked to idiopathic interstitial pneumonia.