November 14, 2014

Provided by Michael McCarthy, University of Washington Health Sciences/UW Medicine

New technology closes many gaps in mapping that have long resisted sequencing

Thousands of never-before-seen genetic variants in the human genome have been uncovered using a new sequencing technology. These discoveries close many human genome mapping gaps that have long resisted sequencing.

The technique, called single-molecule, real-time DNA sequencing (SMRT), may now make it possible for researchers to identify potential genetic mutations behind many conditions whose genetic causes have long eluded scientists, said Evan Eichler, professor of genome sciences at the University of Washington, who led the team that conducted the study.

We now have access to a whole new realm of genetic variation that was opaque to us before, Eichler said. He and his colleagues reported their findings Nov. 10 in the journal Nature.

To date, scientists have been able to identify the genetic causes of only about half of inherited conditions. This puzzle has been called the missing heritability problem. One reason for this problem may be that standard genome sequencing technologies cannot map many parts of the genome precisely.

These approaches map genomes by aligning hundreds of millions of small, overlapping snippets of DNA, typically about 100 bases long, and then analyzing their DNA sequences to construct a map of the genome.

This approach has successfully pinpointed millions of small variations in the human genome. These variations arise from substitution of a single nucleotide base, called a single-nucleotide polymorphisms or SNP.

The standard approach also made it possible to identify very large variations, typically involving segments of DNA that are 5,000 bases long or longer. But for technical reasons, scientists had previously not been able to reliably detect variations whose lengths range from about 50 bases to 5,000 bases in length.

Original post:

Thousands Of Never-Before-Seen Human Genome Variations Uncovered