DNA-dependent ATPase and 5' to 3' DNA helicase required for the maintenance of chromosomal stability. Acts late in the 'Fanconi anemia' pathway, after FANCD2 ubiquitination. Involved in the repair of DNA double-strand breaks by homologous recombination in a manner that depends on its association with BRCA1 (By similarity). ATP + H2O = ADP + H(+) + phosphate Binds 1 [4Fe-4S] cluster. Binds directly to the BRCT domains of BRCA1. Interacts with the CIA complex components CIAO1, CIAO2B and MMS19. Belongs to the DEAD box helicase family. DEAH subfamily.