Considering the pyrimidines of the Watson-Crick base pairs, there are only six different possible substitutions: C>A, C>G, C>T, T>A, T>C, T>G.
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DNA substitution mutations are of two types. Transitions are interchanges of two-ring purines (A↔G) or of one-ring pyrimidines (C↔T): they therefore involve bases of similar shape. Transversions are interchanges of purine for pyrimidine bases, which therefore involve exchange of one-ring and two-ring structures.
Type | SNV classes |
---|---|
Ti | C>T, T>C |
Tv | C>A, C>G, T>A, T>G |
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Number of genetic alternations detected within an individual.
VAF is used to infer whether a variant comes from somatic cells or inherited from parents when a matched normal sample is not provided. A variant is potentially a germline mutation if the VAF is approximately 50% or 100%.
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