title: Concurrent nucleotide substitution mutations in the human genome are characterized by a significantly decreased transition/transversion ratio.
abstract: There is accumulating evidence that the number of multiple-nucleotide substitutions (MNS) occurring in closely spaced sites in eukaryotic genomes is significantly higher than would be predicted from the random accumulation of independently generated single-nucleotide substitutions (SNS). Although this excess can in principle be accounted for by the concept of transient hypermutability, a general mutational signature of concurrent MNS mutations has not so far been evident. Employing a dataset (N = 449) of "concurrent" double MNS mutations causing human inherited disease, we have identified just such a mutational signature: concurrently generated double MNS mutations exhibit a >twofold lower transition/transversion ratio (termed RTs/Tv ) than independently generated de novo SNS mutations (<0.80 vs. 2.10; P = 2.69 × 10(-14) ). We replicated this novel finding through a similar analysis employing two double MNS variant datasets with differing abundances of concurrent events (150,521 variants with both substitutions on the same haplotypic lineage vs. 94,875 variants whose component substitutions were on different haplotypic lineages) plus 5,430,874 SNS variants, all being derived from the whole-genome sequencing of seven Chinese individuals. Evaluation of the newly observed mutational signature in diverse contexts provides solid support for the postulated role of translesion synthesis DNA polymerases in transient hypermutability.
authors.affiliation: Beijing Genomics Institute (BGI)-Shenzhen, Shenzhen, China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Zhu
authors.forename: David N
authors.initials: DN
authors.lastname: Cooper
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhao
authors.forename: Ye
authors.initials: Y
authors.lastname: Wang
authors.forename: Ruihong
authors.initials: R
authors.lastname: Liu
authors.forename: Qibin
authors.initials: Q
authors.lastname: Li
authors.forename: Claude
authors.initials: C
authors.lastname: Férec
authors.forename: Yiming
authors.initials: Y
authors.lastname: Wang
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Chen
mesh_terms: D030342:Genetic Diseases, Inborn / Q000235:genetics; D015894:Genome, Human; D006801:Humans; D009711:Nucleotides / Q000378:metabolism*; D017354:Point Mutation
chemical_list: D009711:Nucleotides
keywords: multiple nucleotide substitutions; spontaneous germline mutations; translesion synthesis DNA polymerases