The evidence of autoantibodies against CD4-T-cells in ALPS-FAS led us to further characterize the phenotypic and functional features of Tfh in such immunological context, as this T-cell subsets is a key regulator of the B-cell function (24) that has never been previously investigated in patients with ALPS-FAS. The gene discussed is CD4; the disease is autoimmune lymphoproliferative syndrome.