Consequently, ALT tumours are generally defined according to a combination of two or more markers [2], including i) the presence of long and heterogeneous telomeres and of extrachromosomal telomeric DNA (e.g. c-circle DNA); ii) the occurrence of spontaneous and telomeric-localized DNA damage; iii) the presence of ALT-associated promyelocytic leukaemia (PML) bodies (APB), a subset of PML nuclear bodies containing telomeric DNA and telomere-associated proteins/DNA repair factors; iv) the absence of TA and v) the loss/reduced expression and/or mutations of the chromatin remodeler ATRX [3, 4]. The gene discussed is PML; the disease is neoplasm.