Blockbusters in the World of Evolutionary Genetics

In lieu of a dearth of Hollywood movie blockbusters this summer, apparently geneticists are trying to take up the slack by premiering some astounding finds in the world of basic genetics research. Two papers in particular have caught my eye, both published in the journal, Nature. Both have widespread implications for understanding evolutionary trends in genetic inheritance as well as predictive value in deciphering how genotype-to-phenotype occurs, something of great relevance to conditions with genetic underpinnings.

The first study by Yang et al. (2015) reports on an interesting phenomenon regarding genetic variability and its previously-unknown relationship to mutation vulnerability. The team found while studying the genome of certain plant and insect populations that heterozygosity in areas in which chromosomal crossover occurred tended to increase the rate of mutations, both large and small, in those areas. What that means is that if you inherit two different copies of a gene, one from your mother, one from your father, and that gene happened to lie in a region in which genetic material is usually exchanged and spliced between your maternally-inherited and paternally-inherited chromosomes, the likelihood of mutations occurring in your genome in those regions increases significantly.

Crossing_Over_1

The team also found that these areas of the genome tended to be under greater pressure from balancing or positive selection, which promotes and ensures polymorphisms for the same gene. Whereas, genes under natural or negative selection had lower crossing-over and mutation rates.

This may be particularly relevant for the human population given the rate at which we are now intermixing due to the internationalization of our larger culture, whereas at one point polymorphisms may have been more locally confined. As such, we may in fact expect to see a minor increase in conditions related to mutations in those vulnerable areas.

The other study by Jordan et al. (2015) reports that, surprisingly, a number of disease-causing mutations in humans are found in other species but without detrimental effect. Because of this, the team hypothesized that the other species may house additional variants within the same gene that essentially negate the effect of the deleterious mutation.

They went on to develop a model of genetic interaction to predict whether a second intra-gene variant was the protective factor, studying two human disease-related genes. They discovered that in both cases there was a benign residue that was responsible for the silencing of the deleterious mutation and that this residue was found in the other unaffected species.

The model that this team has developed, alongside the awareness of so simple a genetic pattern that could underlie a subset of disease states, may help scientists to better understand a wider spectrum of pathogeneses and how and when intervention may be possible.

Well, some great stuff from the world of genetics research this summer. Hope the trend continues!

 

One response to “Blockbusters in the World of Evolutionary Genetics

  1. ‘Abstract
    Mutations generate sequence diversity and provide a substrate for selection. The rate of de novo mutations is therefore of major importance to evolution. Here we conduct a study of genome-wide mutation rates by sequencing the entire genomes of 78 Icelandic parent-offspring trios at high coverage. We show that in our samples, with an average father’s age of 29.7, the average de novo mutation rate is 1.20 × 10(-8) per nucleotide per generation. Most notably, the diversity in mutation rate of single nucleotide polymorphisms is dominated by the age of the father at conception of the child. The effect is an increase of about two mutations per year. An exponential model estimates paternal mutations doubling every 16.5 years. After accounting for random Poisson variation, father’s age is estimated to explain nearly all of the remaining variation in the de novo mutation counts. These observations shed light on the importance of the father’s age on the risk of diseases such as schizophrenia and autism’.

    http://www.ncbi.nlm.nih.gov/pubmed/22914163

    All males generate sperm mutations throughout their lives and sperm mutations increase with advancing age.:

    http://www.ncbi.nlm.nih.gov/pubmed/20931230

    Where do they come from? Benzene is one contributing factor for sperm aneuploidy eg. Down syndrome, Klinefelter syndrome:

    http://cerch.org/benzene-exposure-near-the-us-permissible-limit-is-associated-with-sperm-aneuploidy-june-2010/

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s