Notably, individuals with LC also had uniquely elevated median levels of IL-4/IL-6 double-positive CD4+ T cells (0.3% (LC), 0.2% (CC) and 0.2% (HC)) and IL-4/IL-6 double-positive CD8+ T cells (0.5% (LC), 0.2% (CC) and 0.2% (HC)) (Extended Data Figs. 2f and 4f). This evidence concerns the gene IL4 and laryngotracheoesophageal cleft.