Individual differences caused by shuffled chunks of DNA in the hu...( New Haven Conn. A study by Yale re...)

New Haven, Conn. A study by Yale researchers offers a new view of what causes the greatest genetic variability among individuals suggesting that it is due less to single point mutations than to the presence of structural changes that cause extended segments of the human genome to be missing, rearranged, or present in extra copies.

The focus for identifying genetic differences has traditionally been on point mutations or SNPs changes in single bases in individual genes, said Michael Snyder, the Cullman Professor of Molecular, Cellular & Developmental Biology and senior author of the study, which was published in Science Express. Our study shows that a considerably greater amount of variation between individuals is due to rearrangement of big chunks of DNA.

Although the original human genome sequencing effort was comprehensive, it left regions that were poorly analyzed. Recently, investigators found that even in healthy individuals, many regions in the genome show structural variation. This study was designed to fill in the gaps in the genome sequence and to create a technology to rapidly identify structural variations between genomes at very high resolution over extended regions.

We were surprised to find that structural variation is much more prevalent than we thought and that most of the variants have an ancient origin. Many of the alterations we found occurred before early human populations migrated out of Africa, said first author Jan Korbel, a postdoctoral fellow in the Department of Molecular Biophysics & Biochemistry at Yale.

To look at structural variants that were shared or different, DNA from two females one of African descent and one of European descent was analyzed using a novel DNA-based methodology called Paired-End Mapping (PEM). Researchers broke up the g
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