Substitutions Are Boring: Some Arguments about Parallel Mutations and High Mutation Rates

Press, Maximilian O.; Hall, Ashley N.; Morton, Elizabeth A.; Queitsch, Christine

doi:10.1016/j.tig.2019.01.002

Cited by 50 publications

(40 citation statements)

References 117 publications

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“…In comparison to single nucleotide substitutions, short tandem repeats (STRs) offer a significantly more versatile reservoir of genetic variations that may be necessary for speciation and species-specific phenotypes [1,2]. We have previously reported that approximately 2% of the human protein-coding genes contain STRs of ≥6 repeats in the critical core promoter region [3].…”

Section: Introductionmentioning

confidence: 99%

Natural Selection at the NHLH2 Core Promoter Exceptionally Long CA-Repeat in Human and Disease-Only Genotypes in Late-Onset Neurocognitive Disorder

Afshar¹,

Adelirad²,

Kowsari³

et al. 2020

Gerontology

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Background: Approximately 2% of the human core promoter short tandem repeats (STRs) reach lengths of ≥6 repeats, which may in part be a result of adaptive evolutionary processes and natural selection. A single-exon transcript of the human nescient helix loop helix 2 (NHLH2) gene is flanked by the longest CA-repeat detected in a human protein-coding gene core promoter (Ensembl transcript ID: ENST00000369506.1). NHLH2 is involved in several biological and pathological pathways, such as motivated exercise, obesity, and diabetes. Methods: The allele and genotype distribution of the NHLH2 CA-repeat were investigated by sequencing in 655 Iranian subjects, consisting of late-onset neurocognitive disorder (NCD) as a clinical entity (n = 290) and matched controls (n = 365). The evolutionary trend of the CA-repeat was also studied across vertebrates. Results: The allele range was between 9 and 25 repeats in the NCD cases, and 12 and 24 repeats in the controls. At the frequency of 0.56, the 21-repeat allele was the predominant allele in the controls. While the 21-repeat was also the predominant allele in the NCD patients, we detected significant decline of the frequency (p < 0.0001) and homozygosity (p < 0.006) of this allele in this group. Furthermore, 12 genotypes were detected across 16 patients (5.5% of the entire NCD sample) and not in the controls (disease-only genotypes; p < 0.0003), consisting of at least one extreme allele. The extreme alleles were at 9, 12, 13, 18, and 19 repeats (extreme short end), and 23, 24, and 25 repeats (extreme long end), and their frequencies ranged between 0.001 and 0.04. The frequency of the 21-repeat allele significantly dropped to 0.09 in the disease-only genotype compartment (p <

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Section: Introductionmentioning

confidence: 99%

Natural Selection at the NHLH2 Core Promoter Exceptionally Long CA-Repeat in Human and Disease-Only Genotypes in Late-Onset Neurocognitive Disorder

Afshar¹,

Adelirad²,

Kowsari³

et al. 2020

Gerontology

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“…As such, it will be important to reveal if these variants show functional variability in these genes. Recently, the importance of variation sources resulting in the occurrence of parallel mutations has been highlighted [56].…”

Section: Discussionmentioning

confidence: 99%

Stowaway miniature inverted repeat transposable elements are important agents driving recent genomic diversity in wild and cultivated carrot

et al. 2019

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BackgroundMiniature inverted repeat transposable elements (MITEs) are small non-autonomous DNA transposons that are ubiquitous in plant genomes, and are mobilised by their autonomous relatives. Stowaway MITEs are derived from and mobilised by elements from the mariner superfamily. Those elements constitute a significant portion of the carrot genome; however the variation caused by Daucus carota Stowaway MITEs (DcStos), their association with genes and their putative impact on genome evolution has not been comprehensively analysed.ResultsFourteen families of Stowaway elements DcStos occupy about 0.5% of the carrot genome. We systematically analysed 31 genomes of wild and cultivated Daucus carota, yielding 18.5 thousand copies of these elements, showing remarkable insertion site polymorphism. DcSto element demography differed based on the origin of the host populations, and corresponded with the four major groups of D. carota, wild European, wild Asian, eastern cultivated and western cultivated. The DcStos elements were associated with genes, and most frequently occurred in 5′ and 3′ untranslated regions (UTRs). Individual families differed in their propensity to reside in particular segments of genes. Most importantly, DcSto copies in the 2 kb regions up- and downstream of genes were more frequently associated with open reading frames encoding transcription factors, suggesting their possible functional impact. More than 1.5% of all DcSto insertion sites in different host genomes contained different copies in exactly the same position, indicating the existence of insertional hotspots. The DcSto7b family was much more polymorphic than the other families in cultivated carrot. A line of evidence pointed at its activity in the course of carrot domestication, and identified Dcmar1 as an active carrot mariner element and a possible source of the transposition machinery for DcSto7b.ConclusionStowaway MITEs have made a substantial contribution to the structural and functional variability of the carrot genome.

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“…This highlights the fact that, while not frequently measured or modeled, rates of mutation other than base substitution rates are critical to quantify and understand, as they may be much greater sources of genetic variation, both in terms of frequency and the size of the mutations that occur, than the simple substitution of one nucleotide for another (Press et al 2019). While bsMRs will likely remain the most commonly measured mutation rate, our prediction that there would be little to no correlation between those rate estimates with TE mutation rates bore out ( Figure 4A and B), even though they do positively correlate with microsatellite rates (Ho et al 2020).…”

Section: Correlations With Te Mutation Ratesmentioning

confidence: 99%

Engines of change: Transposable element mutation rates are high and vary widely among genotypes and populations ofDaphnia magna

Bellis

Calkins

et al. 2020

Preprint

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Transposable elements (TEs) represent a large and dynamic portion of most eukaryotic genomes, yet little is known about their mutation rates or the correspondence between rates and long-term patterns of accrual. We compare TE activity over long and short time periods by quantifying TE profiles and mutation rates (with and without minimizing selection) among 9 genotypes from three populations of Daphnia magna sampled along a latitudinal gradient. The patterns of genome-wide variation observed in nature mirror direct estimates of rates and spectra observed in a multi-year laboratory mutation accumulation experiment, where net rates range from -11.98 to 12.79 x 10-5 per copy per generation across genotypes. Overall, gains outnumber losses and both types of events are highly deleterious based on comparing lines with and without selection minimized. The rate and spectrum of TE mutations vary widely among genotypes and across TE families/types, even within the same population. We compare TE mutation rates to previously published rates of base substitution, microsatellite mutation, and gene conversion for the same genotypes, and show a correlation only with the latter. Our study provides strong evidence for the notion that TEs represent a highly mutagenic force in the genome. Furthermore, the variation we observe underscores the need to expand the repertoire of mutations studied to include a wider array of mutation types with different underlying mechanisms in order to better understand the evolution of the mutation rate and the ways in which genetic variation is generated genome wide.

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Substitutions Are Boring: Some Arguments about Parallel Mutations and High Mutation Rates

Cited by 50 publications

References 117 publications

Natural Selection at the NHLH2 Core Promoter Exceptionally Long CA-Repeat in Human and Disease-Only Genotypes in Late-Onset Neurocognitive Disorder

Natural Selection at the NHLH2 Core Promoter Exceptionally Long CA-Repeat in Human and Disease-Only Genotypes in Late-Onset Neurocognitive Disorder

Stowaway miniature inverted repeat transposable elements are important agents driving recent genomic diversity in wild and cultivated carrot

Engines of change: Transposable element mutation rates are high and vary widely among genotypes and populations ofDaphnia magna

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