Subscribe to the BioNews newsletter for free

Login
Advanced Search

Search for
BioNews

Like the Progress Educational Trust on Facebook



 

New human genome maps identify large regions of genetic variability

06 May 2008

By Dr Rachael Panizzo

Appeared in BioNews 456

A new study, published in the journal Nature, has mapped the genome of eight individuals and revealed large regions of genetic variability. An international collaboration led by Evan Eichler at the Howard Hughes Medical Institute compared the genome of four African, two Asian, and two European individual against the reference DNA sequence from the Human Genome Project, and identified large segments of DNA that were variable between individuals, from thousands to hundreds of thousands of base pairs long. A base pair is one 'chemical letter' of DNA code. This study illustrates the complexity of the human genome at the structural level, and the variability identified may lead to new genetic associations with diseases such as autism, diabetes, heart disease, and epilepsy.

The researchers identified nearly 1700 sites of structural variability in the genome: the deletion, insertion, inversion, or multiple copies of large segments of DNA or genes. At some sites, the DNA of each individual was different, while at others only some individuals varied. Fifty per cent of the DNA segments were previously unrecognised as areas of large variability within the genome, and 525 of the identified DNA segments were absent from the original HGP reference genome. 'These results strongly argue that the human genome sequence is still incomplete,' Eichler concluded, adding: 'This represents uncharted territory that can now be examined in more detail to determine the function of these new segments of the human genome with respect to disease and gene activity.'

Sites of small scale, single base pair genetic variation have been well characterised in the human genome, and these are used in clinical applications detecting the genetic risk of disease. Previous studies have also described the existence of mechanisms for the large-scale genetic variability, without describing their exact location or frequency in the genome. In this research, Eichler and his colleagues developed a new sequencing technology, and succeeded in systematically mapping the whole genome of the eight individuals, identifying what type of genetic variability exists at which sites within the human genome. Eichler stressed that high quality genetic mapping was key to identify these large structural differences between individuals. In the research paper, the authors speculated that this new technique would be a 'prelude to future individual genome sequencing projects', an additional tool in building more comprehensive maps of genetic variability in individuals.

Why some sites within the genome are prone to large-scale changes between individuals is currently not understood, but researchers believe that the sites are unstable or rapidly evolving. Regions of high copy numbers of genes are more prone to genetic variability. The new genome maps will be a valuable resource for the genetics community, and will allow researchers to investigate the processes that shape the human genome and human evolution, and may lead to new genetic associations with disease.

SOURCES & REFERENCES
ScienceDaily | 02 May 2008
 
Howard Hughes Medical Institute | 05/2008
 

RELATED ARTICLES FROM THE BIONEWS ARCHIVE

30 November 2009 - by Dr Will Fletcher 
The first genetic historical map of the Han Chinese has been published in the American Journal of Human Genetics by scientists from the Genome Institute of Singapore (GIS). Based on genome-wide variation in 8,200 individuals, the new map has provided many insights into the evolutionary history and population structure of the Han Chinese which is the largest ethnic population in the world. The map is of great importance as it has helped uncover subtle differences in the genetic ...

30 October 2007 - by Ailsa Stevens 
The International HapMap Consortium, a public-private effort to identify and catalogue genetic similarities and differences in humans, this month unveiled its second-generation version of the human genome; a map three times more detailed than the original version released in 2005. The new map will help scientists to...
10 September 2007 - by Dr Jess Buxton 
The scientist who lead the private effort to sequence the human genome has revealed his own complete genetic make-up. The unveiling of J. Craig Venter's genome in the open access journal PloS Biology marks the first time that the complete DNA sequence of an individual has...
27 November 2006 - by Dr Laura Bell 
New research from 13 different research centres in Britain and the US has revealed an unsuspected amount of variation between each individual's DNA. The research, published simultaneously in the journals Nature, Nature Genetics and Genome Research gives a much more comprehensive picture of human genetic variation...

HAVE YOUR SAY
Be the first to have your say.

You need to or  to add comments.

By posting a comment you agree to abide by the BioNews terms and conditions


- click here to enquire about using this story.

Published by the Progress Educational Trust

CROSSING FRONTIERS

Public Conference
London
8 December 2017

Speakers include

Professor Azim Surani

Professor Magdalena Zernicka-Goetz

Professor Robin Lovell-Badge

Sally Cheshire

Professor Guido Pennings

Katherine Littler

Professor Allan Pacey

Dr Sue Avery

Professor Richard Anderson

Dr Elizabeth Garner

Dr Andy Greenfield

Dr Anna Smajdor

Dr Henry Malter

Vivienne Parry

Dr Helen O'Neill

Dr César Palacios-González

Philippa Taylor

Fiona Fox

Sarah Norcross

Sandy Starr


BOOK HERE

Good Fundraising Code

Become a Friend of PET HERE and give the Progress Educational Trust a regular donation