Fanconi anemia group D2 protein is a protein that in humans is encoded by the FANCD2 gene. The Fanconi anemia complementation group (FANC) currently includes FANCA, FANCB, FANCC, FANCD1 (also called BRCA2), FANCD2 (this gene), FANCE, FANCF, FANCG, and FANCL.2177211651ENSG00000144554ENSMUSG00000034023Q9BXW9Q80V62NM_001018115NM_033084NM_001319984NM_001033244NM_001347350NP_001018125NP_001306913NP_149075NP_001028416NP_001334279Fanconi anemia is a genetically homozygous recessive disorder characterized by chromosomal instability, hypersensitivity to DNA crosslinking agents, increased chromosomal breakage, and defective DNA repair. The members of the Fanconi anemia complementation group do not share sequence similarity; they are related by their assembly into a common nuclear protein complex. This gene encodes the protein for complementation group D2. This protein is monoubiquitinated in response to DNA damage, resulting in its localization to nuclear foci with other proteins (BRCA1 and BRCA2) involved in homology-directed DNA repair (see Figure: Recombinational repair of DNA double-strand damages). A nuclear complex containing FANCA, FANCC, FANCF and FANCG proteins is required for the activation of the FANCD2 protein to the mono-ubiquitinated isoform. Mono-ubiquination of FANCD2 is essential for repairing DNA interstrand crosslinks.Humans with a FANCD deficiency display hypogonadism, male infertility, impaired spermatogenesis, and reduced female fertility. Similarly, mice deficient in FANCD2 show hypogonadism, impaired fertility and impaired gametogenesis.Tobacco smoke suppresses the expression of FANCD2, which codes for a DNA damage 'caretaker' or repair mechanism.FANCD2 has been shown to interact with: