MUC5B and idiopathic pulmonary fibrosis: NGS identified causative variants (including a novel one) in five patients (5/37, 13.5%) and confirmed the high prevalence of <i>MUC5B</i> promoter polymorphism rs35705950, including the detection of a previously unreported form in IPF SNP (indicated as "novel" in the main text), rs141420125 (23/37; 62%).