Finally, we note that the dual fluorescence flow cytometric assay for recombination in DF cells is quantitatively responsive to DNA double strand breaks and the manipulation of DNA repair pathways, indicating that this is a robust gateway system that could be adapted to the analysis of Alu-mediated homologous recombination in the human BRCA1 locus in breast tumors (6) and other diseases including FA (9,128), or more generally to probe the causes and consequences of DSBs in human cells (129). The gene discussed is BRCA1; the disease is breast neoplasm.