In Nature Genetics this week, two research groups present studies describing genomic alteration patterns for different tumor types. One team, led by Memorial-Sloan Kettering researchers, provided a hierarchical classification of 3,299 tumors from 12 cancer types from The Cancer Genome Atlas Pan-Cancer dataset. Notably, they identified a separation between tumors with primarily point mutations, which trigger changes in protein sequences, and those with primarily copy number alterations, in which the cell has an abnormal number of copies of one or several genomic regions. In the other paper, investigators from the Broad Institute and elsewhere characterized non-germline copy number alterations in 11 cancer types and 4,934 primary cancer specimens from the same dataset. They found whole-genome doubling in 37 percent of cancers, which was associated with higher rates of all non-germline copy number alterations.
Meanwhile, in Nature Methods, a group from the European Molecular Biology Laboratory describes a new approach for dealing with technical noise in single-cell RNA-sequencing experiments. The statistical method distinguishes between "true biological variability from the high levels of technical noise" in such experiments and quantifies the "statistical significance of observed cell-to-cell variability in expression strength on a gene-by-gene basis," the researchers say.