GENETICS 677 Lecture Notes - Lecture 3: Dna Repair, Stomach Cancer, Somatic Hypermutation
Document Summary
Lecture 3: student presentation 1 signatures of mutational processes in human cancer, by a massive number of people. Somatic mutations: variable within and between cancers, childhood cancers carry fewer mutations than adult cancers, chronic exposures to mutagens, location and context contribute to mutations. Limitations: several factors influence the ability to extract mutational signatures. Similarities between mutational processes resulting in the same mutations. Overview of mutations: 6 classes of base substitution, resulting in 96 possible mutations. 21 of 30 cancer types had distinct validated mutational signatures. Others covered most of the possible mutations: signatures 1a and 1b. Characterized by ctot substitutions, found in 25 of 30 cancer classes, possibly caused by elevated rate of spontaneous deamination. Evidence pointed to these being acquired over the lifetime of the patient: signature 2. Characterized by ctog and ctot mutations, found in 16 of 30 cancer classes, possibly caused by defects in base excision repair machinery. Transcriptional strand bias signatures: signature 4, ctoa.
