The role of USP44 in the Fanconi anemia DNA repair pathway was investigated using chromosome analysis of wild-type or Usp44-knockout cells after exposure to mitomycin C. Results: We identified 146 proteins that were selectively retrieved by the USP44 construct and compared with cells expressing the BioID ligase alone, including 15 gene products encoded by genes on tier 1 of the COSMIC Cancer Gene Census, including BRCA2. The gene discussed is USP44; the disease is Fanconi anemia.