Major criteria are >5 × 109/L of T-PLL lymphocytes in peripheral blood or bone marrow, T-cell clonality, and abnormalities of 14q32 or Xq28 or expression of TCL1A/B or MTCP1. Minor criteria include abnormalities of chromosome 11 (11q22.3; ATM); abnormalities of chromosome 8 (idic(8), t(8; 8), trisomy 8q); abnormalities of chromosomes 5, 12, 13, and 22 or complex chromosome; and involvement of T-PLL specific site (splenomegaly or effusion) [6]. The gene discussed is ATM; the disease is Splenomegaly.