Following the previous identification of a heterozygous mutation of PRF1 in an autoimmune lymphoproliferative syndromes (ALPS) patient, in 2006 Clementi et al. analyzed 14 ALPS and 28 Dianzani autoimmune lymphoproliferative disease (DALD) cases and found a different amino-acid substitution in 2 of 14 ALPS and 6 of 28 DALD. The gene discussed is PRF1; the disease is autoimmune lymphoproliferative syndrome.