LIG1 deficiency is characterized by growth retardation, variable severity of immune deficiency ranging from early onset hypogammaglobulinemia to severe combined immune deficiency, Omenn-like phenotype, reduced α/βT cells and increased proportions of circulating γδ T cells, and erythrocyte macrocytosis without deficiency of vitamin B12 or folate [67,68,69]. Here, LIG1 is linked to Immunodeficiency.