It is noticeable that the immunological findings in MUL patients are similar to the ones showed by children with PLE and Fontan patients with PLE: hypogammaglobulinemia, significant T-cell deficiency with decreased CD4+ and CD8+ count, altered CD4+/CD8+ ratio, and significantly modified CD4+ and CD8+ T-cell phenotype toward effector and terminal differentiated T cells with loss of naïve CD45RA+ lymphocytes (22–24). Here, CD4 is linked to congenital T-cell immunodeficiency.