Folate stress as a contributing factor to Fanconi anemia

Abstract Fanconi Anemia (FA) is a rare chromosomal instability disorder characterized by progressive bone marrow failure, congenital abnormalities, and a heightened cancer predisposition. With at least 22 identified FA genes, biallelic mutations in any one of these genes disrupt the FA pathway, a specialized DNA repair mechanism, leading to disease pathogenesis. FA cells are hypersensitive to DNA interstrand crosslinks (ICLs), which have been linked to endogenous aldehydes and oxidative stress, both contributing factors to FA pathogenesis. Our previous work identified replication stress as a significant driver of FA pathology, demonstrating that FA-deficient cells are particularly vulnerable to persistent replication stress. Here, we reveal that folate deficiency, a condition impairing DNA synthesis, repair, and methylation, constitutes a previously unrecognized contributing factor to FA. We show that folate stress causes aberrant DNA replication in FA-deficient cells, leading to chromosomal loss and proliferation delay. Mechanistically, the FA pathway is activated under folate stress and engages a break-induced replication (BIR)-like process to mitigate replication-associated damage. Importantly, feeding Fancl −/− mice a folate-deficient diet induced bone marrow failure, recapitulating a hallmark FA symptom. Our findings suggest that folate supplementation may offer a potential strategy for ameliorating FA symptoms.