University of Utah study sheds light on rate of gene mutations

For all of the blame Americans like to foist on their parents for whatever ails them, a researcher at the University of Utah says mom and dad pass far fewer genetic mutations on to their children than previously thought.

Researchers at the U. and other research labs have sequenced the entire genome of a family of four — parents, a daughter and a son. It's the first time that's ever been done, according to Lynn B. Jorde, professor and chair of the U.'s department of human genetics.

He and his colleagues now believe parents pass 30 genetic mutations each along to their children, for a total of 60, he said. Scientists had long believed the total mutations passed to children from parents was 75 from each, or a total of 150.

Jorde said the study is important for two major reasons.

"First, we wanted to get an estimate of the human mutation rate since that's never been estimated directly for the entire genome. Previous estimates were based on much smaller sections of the DNA, but this is for all DNA," Jorde said.

"Also, this family does have genetic disease, and we were interested in which mutation gives rise to the cause of that disease."

The study, led by scientists at the Seattle-based Institute for Systems Biology, is to be published Thursday in the journal Science Express.

The findings "don't change our understanding of whether mutations are passed on to offspring, but they do change our understanding of how frequently new mutations take place," Jorde said.

The work will enable researchers to identify precise locations where parental chromosomes exchange information that creates new combinations of genetic traits in their children.

Jorde said predicting the mutation rate estimate is important "when we look at variation from one person or population to another because one of the questions we always ask is how long would it take for a variation to arise. Now that we know how many there are, we know better what time length is required to give rise to the variation we see."

"The mutation rate is our clock, and every time it ticks we have a new genetic variant," Jorde said. "We need to know how fast the clock ticks."