Congenital disorder of glycosylation Ia (CDGIa) is an autosomal recessive disease that is caused by mutations in the gene PMM2 encoding phosphomannomutase, an enzyme that synthesizes mannose-1-phosphate, an important intermediate for the N-glycan biosynthesis. Here, we investigated the susceptibility of CDGIa fibroblasts to cell death induction. CDGIa fibroblasts were more sensitive than control fibroblasts to staurosporine-induced apoptosis. Supplementation with mannose, which corrects N-glycosylation in CDGIa fibroblasts, did not abrogate their higher sensitivity to staurosporine. These results show that the sensitivity of CDGIa fibroblasts to apoptosis is not directly related to their defective N-glycosylation.