Neighboring-nucleotide effects on single nucleotide polymorphisms: a study of 2.6 million polymorphisms across the human genome.

Zhao Z, Boerwinkle E
Genome Res. 2002 12 (11): 1679-86

PMID: 12421754 · PMCID: PMC187558 · DOI:10.1101/gr.287302

We investigated substitution patterns and neighboring-nucleotide effects for 2,576,903 single nucleotide polymorphisms (SNPs) publicly available through the National Center for Biotechnology Information (NCBI). The proportions of substitutions were A/G, 32.77%; C/T, 32.81%; A/C, 8.98%; G/T, 9.06%; A/T, 7.46%; and C/G, 8.92%. The two nucleotides immediately neighboring the variable site showed major deviation from genome-wide and chromosome-specific expectations, although lesser biases extended as far as 200 bp. On the 5' side, the biases for A, C, G, and T were 1.43%, 4.91%, -1.70%, and -4.62%, respectively. These biases were -4.44%, -1.59%, 5.05%, and 0.99%, respectively, on the 3' side. The neighboring-nucleotide patterns for transitions were dominated by the hypermutability effects of CpG dinucleotides. Transitions were more common than transversions, and the probability of a transversion increased with increasing A + T content at the two adjacent sites. Neighboring-nucleotide biases were not consistent among chromosomes, with Chromosomes 19 and 22 standing out as different from the others. These data provide genome-wide information about the effects of neighboring nucleotides on mutational and evolutionary processes giving rise to contemporary patterns of nucleotide occurrence surrounding SNPs.

MeSH Terms (8)

Base Composition Chromosomes, Human, Pair 19 Chromosomes, Human, Pair 22 Genome, Human Humans Nucleotides Polymorphism, Single Nucleotide Sequence Analysis, DNA

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