FANCD2 and Fanconi anemia: The central complex in this pathway is formed by the Fanconi anemia complementation group D2 (Fancd2), a core component of the Fanconi anemia complex, and FAI (FANCI) proteins forming the FANC1-FANCD2 (ID) complex that are phosphorylated by ATR (ataxia telangiectasia and Rad3-related).