The immunophenotypic analysis confirmed a lower percentage of CD4 T-cells [median 38% (IQR: 25–45) vs. 51% (IQR: 34–53), n = 7, and n = 14, respectively, p = 0.02] associated with a relative increase in the proportion of CD8 [median 44% (IQR: 34–54) vs. 30% (IQR: 26–38), n = 7, and n = 14, respectively, p = 0.01] and no differences in the proportion of DNT in CD4 lymphopenic ALPS-FAS patients compared to matched control ALPS-FAS patients without CD4 T-cells lymphopenia (Figure 3C). Here, CD4 is linked to autoimmune lymphoproliferative syndrome.