We all have hundreds of DNA flaws, UK geneticists say

Everyone has on average 400 flaws in their DNA, a UK study suggests. Most are “silent” mutations and do not affect health, although they can cause problems when passed to future generations. Others are linked to conditions such as cancer or heart disease, which appear in later life, say geneticists.

The evidence comes from the 1,000 Genomes project, which is mapping normal human genetic differences, from tiny changes in DNA to major mutations.

In the study, 1,000 seemingly healthy people from Europe, the Americas and East Asia had their entire genetic sequences decoded, to look at what makes people different from each other, and to help in the search for genetic links to diseases.

The new research, published in The American Journal of Human Genetics, compared the genomes of 179 participants, who were healthy at the time their DNA was sampled, with a database of human mutations developed at Cardiff University.

It revealed that a normal healthy person has on average about 400 potentially damaging DNA variations, and two DNA changes known to be associated with disease.

"Ordinary people carry disease-causing mutations without them having any obvious effect," said Dr Chris Tyler-Smith, a lead researcher on the study from the Wellcome Trust Sanger Institute, Cambridge.

He added: “In a population there will be variants that have consequences for their own health.”

The research gives an insight into the “flaws that make us all different, sometimes with different expertise and different abilities, but also different predispositions in diseases,” said Prof David Cooper of Cardiff University, the other lead researcher of the study.

Global Genome Effort Seeks Genetic Roots of Disease

By decoding the genomes of more than 1,000 people whose homelands stretch from Africa and Asia to Europe and the Americas, scientists have compiled the largest and most detailed catalog yet of human genetic variation. The massive resource will help medical researchers find the genetic roots of rare and common diseases in populations worldwide.

The 1000 Genomes Project involved some 200 scientists at Washington University School of Medicine in St. Louis and other institutions. Results detailing the DNA variations of individuals from 14 ethnic groups are published Oct. 31 in the journal Nature. Eventually, the initiative will involve 2,500 individuals from 26 populations.

“With this resource, researchers have a roadmap to search for the genetic origins of diseases in populations around the globe,” says one of the study’s co-principal investigators, Elaine Mardis, PhD, co-director of The Genome Institute at Washington University. “We estimate that each person carries up to several hundred rare DNA variants that could potentially contribute to disease. Now, scientists can investigate how detrimental particular rare variants are in different ethnic groups.”