Considering the increased amount of genomic instability seen in MM, the disregulated CD40/interleukin-4 (IL-4) pathway in MM cells [23], and the role of Ku in DNA DSBR and non-homologous end-joining (NHEJ), we investigated the presence of Ku86 and its variants in MM cells, and compared them to T lymphocytes and other cell lines. The gene discussed is XRCC5; the disease is Miyoshi myopathy.