ORIGINAL ARTICLE Mitochondrial D310 mutation as clonal marker for solid tumors

Abstract Patients with multiple tumors, either synchronous or metachronous, can have metastatic disease or suffer from mul-tiple independent primary tumors. While proper diagnosis of these patients is important for prognosis and treatment, this can be challenging using only clinical and histological criteria. The aim of the present study was to evaluate the value of mitochon-drial D310 mutation analysis in diagnostic questions regarding tumor clonality for awide range of tumor types. Sanger sequenc-ing of D310 was performed on a diagnostic cohort of 382 pa-tients with 857 tumors that were previously analyzed using rou-tine molecular analysis on genomic DNA. The D310 mononu-cleotide repeat was frequently somatically mutated (56/321, 17 %) in several tumor types, including breast, head and neck, gynecological, lung, colorectal, and skin tumors. For 84/327 (26 %) patients, a D310 mutation was detected in at least one of their tumors; for these patients, D310 can be used to deter-mine the clonal relationship between their multiple tumors. Clonality assessments based on mitochondrial DNA (mtDNA) and routine genomic DNA analysis were concordant in 52/73 (71 %) patients. We conclude that D310 mutation status might aid in determining clonality of clinically challenging synchro-nous or metachronous tumors. To this end, next generation sequencing targeted genomic DNA assays should be complemented with mtDNA markers, such as the D310 repeat