However, when comparing the frequencies of the different T cell subsets within the total CD8− (CD4) (Fig. 4a and S3A) and CD8+ (Fig. 4b and S3B) T cell population, percentages of naïve CD8− (CD4) (Fig. 4a and S3A) and naïve CD8+ (Fig. 4b and S3B) T cells were significantly reduced for NBS patients as compared with HI at the youngest age. This evidence concerns the gene CD4 and Nijmegen breakage syndrome.