The Hidden Causes of Mutational Signatures in Tumors

Ludmille Alexandrov is an assistant professor at the University of California, San Diego. He used a mathematical method called blind source separation to identify mutational signatures in tumours. By 2013 he had extracted 20 distinct fingerprints from nearly 5 million mutations in more than 7,000 tumours covering 30 of the most common forms of cancer. That number rose in 2015 to at least 30 unique mutational fingerprints, each caused by a different agent. An even larger analysis of nearly 85 million mutations in around 25,000 cancers raised the number of fingerprints to around 65 - although probably only around 50 of those are truly unique.