Tiny genetic differences have huge consequences

January 19, 2008

A study led by McGill University researchers has demonstrated that small differences between individuals at the DNA level can lead to dramatic differences in the way genes produce proteins. These, in turn, are responsible for the vast array of differences in physical characteristics between individuals.

The study, part of the Genome Regulators in Disease (GRID) Project funded by Genome Canada and Genome Quebec, was led by Dr. Jacek Majewski of McGill University’s Department of Human Genetics and the McGill University and Genome Quebec Innovation Centre, and first-authored by his research associate Dr. Tony Kwan. It was published January 13 in the journal Nature Genetics.

The study was originally initiated by Dr. Tom Hudson, former director of the McGill University and Genome Quebec Innovation Centre, and drew upon the data collected by the vast HapMap (Haplotype Map) Project, a global comparative map of the human genome, which Hudson and his colleagues were instrumental in completing.

This study solves in part the mystery of how a relatively small number of differences within DNA protein coding sequences could be responsible for the enormous variety of phenotypic differences between individuals. It had previously been shown that individual differences reside in simple, relatively small variations in the DNA sequence called single nucleotide polymorphisms (SNPs, often pronounced “snips”), which exist primarily in the “junk code” of the DNA not previously known to have any profound genetic effect.

“There are many SNPs,” explained Dr. Majewski. “If you add them all together, you'd expect that two individuals would differ at more than a million of those positions. So we have a million or more small differences that distinguish you and me, and yet it would be very hard to explain all the phenotypic differences in the way we look, grow, and behave just by the handful of these protein coding differences.”

Majewski and his colleagues have demonstrated that the natural processing of messenger RNA (mRNA), via a process called splicing, is genetically controlled by these SNPs. The SNPs in certain individuals lead to changes in splicing and result in the production of drastically altered forms of the protein. These out-of-proportion consequences may lead to the development of genetic diseases such as cystic fibrosis and Type 1 diabetes.

Source: McGill University

Explore further: Landmark project shows heart disease and arthritis risk raised by genetic changes in blood

Related Stories

New method helps link genomic variation to protein production

November 6, 2012

Scientists have adopted a novel laboratory approach for determining the effect of genetic variation on the efficiency of the biological process that translates a gene's DNA sequence into a protein, such as hemoglobin, according ...

Genetic breakthrough for brain cancer in children

January 30, 2012

An international research team led by the Research Institute of the McGill University Health Centre (RI MUHC) has made a major genetic breakthrough that could change the way pediatric cancers are treated in the future. The ...

Understanding the effects of genes on human traits

July 31, 2013

Recent technological developments in genomics have revealed a large number of genetic influences on common complex diseases, such as diabetes, asthma, cancer or schizophrenia. However, discovering a genetic variant predisposing ...

Recommended for you

UK experts give green light to 'three-parent babies'

November 30, 2016

British scientists on Wednesday approved the use of so-called "three-parent baby" fertility treatments, paving the way for the country to become the first in the world to officially introduce the procedures.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

The_Bill
not rated yet Jan 21, 2008
In conclusion - the large-scale gentic similarities between people accounts for the existence of a single human species, and the "SNIPs" differences account for the variability within the species. Genetics has finally provided an explanation for something many of us have noticed for a very long time now. Congratulations!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.