CD4 and Nijmegen breakage syndrome: By comparing absolute numbers of T cell subsets of NBS patients and HI, it became clear that NBS patients showed reduced numbers of naïve (Fig. 3a, b), memory (Fig. 3c, d), and effector cells (Fig. 3e, f) for both CD8− (CD4) and CD8+ T cells, with most significant effects seen in the naïve and effector T cells.