Identical phenotype in patients with somatic and germline CD95 mutations requires a new diagnostic approach to autoimmune lymphoproliferative syndrome.

In a patient with a somatic mutation in the CD95 gene, the long-term evolution of the clinical phenotype was indistinguishable from that of patients with autoimmune lymphoproliferative syndrome caused by germline CD95 mutations. A new diagnostic algorithm for autoimmune lymphoproliferative syndrome is suggested incorporating studies on sorted TCRalpha/beta+CD3+CD8-CD4- T cells.