Parents pass on 30 changed genes each to their children
Source: Agencies |
March 12, 2010, Friday
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CHILDREN inherit about 30 changed genes from each parent, fewer than had been thought, according to a first detailed look at the blueprint for human life in a family.
Yet that was enough to pass on an inherited illness in that family. And a separate study of an individual genome located the cause of another inherited disease.
That blueprint for life, called DNA, contains about 22,000 genes and researchers calculated the number of changes by analyzing the genes of a mother, father and their son and daughter.
The result, reported in yesterday's edition of the journal Science, found that the children had about 30 mutations from each parent for a total of 60 changes passed to the offspring.
Scientists had previously thought a child had about 75 mutated genes from the parents.
The rate probably will vary somewhat, depending on the age of the parents, said co-author Lynn B. Jorde, chairman of the Department of Human Genetics at the University of Utah School of Medicine.
Most mutations are thought to be unimportant, but the rate at which things change is considered critical, helping explain the gradual development of changes.
Jorde and the senior author David J. Galas of the Institute of Systems Biology in Seattle, Washington, studied a family in which the parents had no genetic abnormalities, but each carried recessive genes that resulted in their son and daughter being born with two extremely rare conditions - Miller's syndrome and primary ciliary dyskinesia.
Miller's syndrome, which causes face and limb malformations, has been diagnosed in only two families in the world. PCD is a condition in which the tiny hair-like structures that are supposed to move mucus out of airways in the lungs do not function. The chances of having PCD are estimated at one in 10,000.
Jorde said the odds of someone having both PCD and Miller's syndrome are less than one in 10 billion.
"We were very pleased and a little surprised at how much additional information can come from examining the full genomes of the same family," Galas said in a statement.
"Comparing the sequences of unrelated individuals is useful, but for a family the results are more accurate. We can now see all the genetic variations, including rare ones, and can construct the inheritance of every piece of the chromosomes, which is critical to understanding the traits important to health and disease."
Meanwhile, a separate report in the New England Journal of Medicine disclosed that Dr James Lupski of Baylor College of Medicine in Texas had sequenced his own complete genome and identified the gene involved in his form of Charcot-Marie-Tooth syndrome, which affects the function of nerves in limbs, hands and feet.
Lupski said he has known for 40 years that he had a disease caused by a recessive gene. Now he has found it.
Yet that was enough to pass on an inherited illness in that family. And a separate study of an individual genome located the cause of another inherited disease.
That blueprint for life, called DNA, contains about 22,000 genes and researchers calculated the number of changes by analyzing the genes of a mother, father and their son and daughter.
The result, reported in yesterday's edition of the journal Science, found that the children had about 30 mutations from each parent for a total of 60 changes passed to the offspring.
Scientists had previously thought a child had about 75 mutated genes from the parents.
The rate probably will vary somewhat, depending on the age of the parents, said co-author Lynn B. Jorde, chairman of the Department of Human Genetics at the University of Utah School of Medicine.
Most mutations are thought to be unimportant, but the rate at which things change is considered critical, helping explain the gradual development of changes.
Jorde and the senior author David J. Galas of the Institute of Systems Biology in Seattle, Washington, studied a family in which the parents had no genetic abnormalities, but each carried recessive genes that resulted in their son and daughter being born with two extremely rare conditions - Miller's syndrome and primary ciliary dyskinesia.
Miller's syndrome, which causes face and limb malformations, has been diagnosed in only two families in the world. PCD is a condition in which the tiny hair-like structures that are supposed to move mucus out of airways in the lungs do not function. The chances of having PCD are estimated at one in 10,000.
Jorde said the odds of someone having both PCD and Miller's syndrome are less than one in 10 billion.
"We were very pleased and a little surprised at how much additional information can come from examining the full genomes of the same family," Galas said in a statement.
"Comparing the sequences of unrelated individuals is useful, but for a family the results are more accurate. We can now see all the genetic variations, including rare ones, and can construct the inheritance of every piece of the chromosomes, which is critical to understanding the traits important to health and disease."
Meanwhile, a separate report in the New England Journal of Medicine disclosed that Dr James Lupski of Baylor College of Medicine in Texas had sequenced his own complete genome and identified the gene involved in his form of Charcot-Marie-Tooth syndrome, which affects the function of nerves in limbs, hands and feet.
Lupski said he has known for 40 years that he had a disease caused by a recessive gene. Now he has found it.
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