Since the Fas/Fas ligand apoptotic system is involved in regulating the survival of normal neutrophils, it has been hypothesised that LGLL-associated neutropaenia might be partially mediated by dysregulation of the Fas ligand, which is thought to be a possible trigger of the neutrophil apoptotic mechanism [28,29]. This evidence concerns the gene FAS and T-cell large granular lymphocyte leukemia.