FA (Fanconi anaemia) is a hereditary disease characterized by congenital malformations, progressive bone marrow failure and an extraordinary elevated predisposition to develop cancer. In the present manuscript we describe an anomalous high level of the proinflammatory cytokine IL-1β (interleukin-1β) present in the serum of FA patients. The elevated levels of IL-1β were completely reverted by transduction of a wild-type copy of the FancA cDNA into FA-A (FA group A) lymphocytes. Although the transcription factor NF-κB (nuclear factor-κB) is a well established regulator of IL-1β expression, our experiments did not show any proof of elevated NF-κB activity in FA-A cells. However, we found that the overexpression of IL-1β in FA-A cells is related to a constitutively activated PI3K (phosphoinositide 3-kinase)-Akt pathway in these cells. We provide evidence that the effect of Akt on IL-1β activation is mediated by the inhibition of GSK3β (glycogen synthase kinase 3β). Finally, our data indicate that the levels of IL-1β produced by FA-A lymphoblasts are enough to promote an activation of the cell cycle in primary glioblastoma progenitor cells. Together, these results demonstrate that the constitutive activation of the PI3K-Akt pathway in FA cells upregulates the expression of IL-1β through an NF-κB-independent mechanism and that this overproduction activates the proliferation of tumour cells.