Additionally, we identified a mutation in the ABCC1 gene (ATP-binding cassette, sub-family C member 1) in Case 5T (Table 3), which matches a mutation in the same functional pathway in ABCA8 gene (ATP-binding cassette, sub-family A member 8) in a pre-treated HCLc case [32], suggesting occurrence prior to therapy and another potential recurrent gene mutation in HCLc disease. Here, ABCC1 is linked to hairy cell leukemia.