CCL4 and laryngotracheoesophageal cleft: Dysregulation of the immune system in LC patients is characterized by an increase in Interferon gamma (IFN-γ) and Interleukin (IL)-2 cytokines, pathological changes in populations of CD4+, CD8+ lymphocyte subpopulations, the monocytic CD14+ and CD16+ subset, deficits of B lymphocytes and monocytes, alterations in the cellular response to SARS-CoV-2 antigens (S, M, N, P proteins) and decreased levels of the Chemokine (C-C motif) ligands 4 (CCL4) [21].