The main features of ALT-positive cells are the presence of long and heterogeneous telomeres and of extrachromosomal linear and circular telomeric DNA fragments, the occurrence of spontaneous telomeric-localized DNA damage, as well as the presence of ALT-associated promielocytic leukemia bodies (APB), which are subnuclear bodies composed of telomeric DNA, shelterin factors and homologous recombination/DNA repair proteins [9]. The gene discussed is GPT; the disease is leukemia.