The characteristics of ALT cells that have been explored to date include the appearance of heterogenous telomere length; high rates of telomeric sister chromatid exchange (T-SCE) [6]; the presence of extra-chromosomal telomeric DNA, such as C-Circle and T-Circle; and the presence of ALT-associated PML (promyelocytic leukemia) bodies (APBs) [7]. This evidence concerns the gene GPT and acute promyelocytic leukemia.