MUC5B and idiopathic pulmonary fibrosis: Whereas eQTLs from healthy lung revealed MUC5B as the causal gene underlying the association of rs35705950 with critically ill COVID-19 and IPF, MUC5B may be atypical in that its expression is largely restricted to mucus-secreting cells and the effect size of the eQTL is large,28 making accurate mapping of this eQTL feasible with smaller numbers and in bulk tissue.