MUC5B and pulmonary fibrosis: Two polymorphic variants rs35705950 of MUC5B that increase susceptibility to pulmonary fibrosis and the common “European” haplotype of TMPRSS2 gene (composed of SNPs rs463727, rs34624090, rs55964536, rs734056, rs4290734, rs34783969, rs11702475, rs35899679, and rs35041537) are totally absent in the Asian population.