Fig. 1

Overview of FA pathway genes identified in eukaryotic lineages. Representative species include mammals (Homo sapiens, Mus musculus, and Gallus gallus), amphibian (African clawed toad, Xenopus laevis), fish (zebrafish, Danio rerio), sea squirt (Ciona intestinalis), insect (Drosophila melanogaster), worm (Caenorhabditis elegans), yeast (Saccharomyces cerevisiae), and plant (Arabidopsis thaliana). FANC genes are grouped into three classes. Group I includes nine genes that encode proteins that form the FA core complex; group II encodes FANCD2 and FANCI that form the D2/I complex; group III comprises eight genes that encode FA effector proteins that function downstream of D2/I complex. Lower eukaryotes tend to be missing orthologues of the FA core complex genes. A = FANCA, B = FANCB, C = FANCC, D2 = FANCD2, E = FANCE, F = FANCF, G = FANCG, I = FANCI, L = FANCL, M = FANCM, D1 = BRCA2/FANCD1, J = BRIP1/FANCJ, N = PALB2/FANCN, O = RAD51C/FANCO, P = SLX4/FANCP, Q = ERCC4/FANCQ/XPF, R = RAD51/FANCR, S = BRCA1/FANCS, T = UBE2T/FANCT. If we extend this gene family update to include prokaryotes, it might be noted that, whereas no orthologs of any of the 19 eukaryotic FANC genes exist in prokaryote genomes, RAD51 (as a nineteenth FANC member in living organisms) qualifies as a homologue of bacterial RecA