BTK and COVID-19: Among the IGHD3 genes, the most expressed is IGHD3-22, which was highly expressed in both COVID-19 patients receiving ECMO (22.94% COVID ECMO D; 17.51% COVID ECMO S), compared to COVID R (15.45%) and the healthy control (13.60%), while the least expressed is IGHD3-3, in both COVID patients that underwent ECMO (8.72% COVID ECMO D; 10.31% COVID ECMO S), compared to COVID R (17.89%) and the healthy control (11.48%) (Figure S2).