FASLG and autoimmune lymphoproliferative syndrome: The typical biomarker for ALPS is an increased number of a normally uncommon population of “double-negative TCRαβ + CD3 + CD4- CD8- T cells” (DNTs); other characteristic laboratory abnormalities include defective lymphocyte apoptosis, elevated levels of interleukin (IL) IL-10, IL-18, vitamin B12, and soluble FAS-ligand (sFASL) [1].