The percentages of perforin+ cells in fresh CD8 lymphocytes of the PL and MM groups were significantly higher than those of the HV group (mean ± S.D., 38.8 ± 26.3, 44.2 ± 24.9, and 17.8 ± 14.5, resp). The gene discussed is PRF1; the disease is Miyoshi myopathy.