FANCD2 is a central component of the Fanconi anemia DNA repair pathway essential for maintaining chr3 stability 1. The FANCI-FANCD2 complex functions as a sliding clamp that surveys double-stranded DNA and stalls at single-stranded-double-stranded DNA junctions, enabling recognition of stalled replication forks and DNA damage sites 2. FANCD2 participates in multiple DNA repair mechanisms including homologous recombination, interstrand crosslink repair, and replication fork protection 3. Upon monoubiquitination by the FA core complex, FANCD2 recruits repair proteins and coordinates resolution of replication stress-induced DNA damage 4. Beyond canonical repair functions, FANCD2 has emerging roles in regulating R-loop formation through interaction with splicing factor SRSF1, linking DNA damage response to mRNA export 4. Mutations in FANCD2 cause Fanconi anemia complementation group D2, characterized by congenital abnormalities, bone marrow failure, and high cancer susceptibility 5. Notably, pathological FANCD2 activation paradoxically promotes chr3 and extrachromosomal DNA formation, driving cancer drug resistance 6. In cancer cells, MYC multimerization stabilizes FANCD2 at replication forks, limiting DNA damage during S-phase and promoting proliferation under stress 7.