Leukoencephalopathy with vanishing white matter (VWM) is an inherited childhood white matter disorder, caused by mutations in the genes encoding eukaryotic initiation factor 2B (eIF2B). The present study showed that, while the eIF2B activity was reduced in VWM lymphoblasts, the expression levels of the eIF2B subunits were similar to control lymphoblast lines. The mutations in eIF2B did not affect the interaction with eIF2. Strikingly, no apparent differences for the regulation of protein synthesis, measured by [³⁵S]-methionine incorporation, were found between control and VWM lymphoblasts. Western blotting showed that, in some VWM cells, exposure to heat shock caused a decrease in the expression of specific eIF2B subunits. Most importantly, the increase in phosphorylation of eIF2α in response to heat shock was lower in VWM lymphoblasts than in control cells. These findings could form part of the explanation for the episodes of rapid and severe deterioration in VWM patients that are precipitated by febrile infections.