Researchers in New Jersey claim that 30 human babies might have been born with genes from three people: their mother, their father — and a third person, whose genes were added in the laboratory.
The researchers call their experiment "the first case of human … genetic modification resulting in normal healthy children."
The team at the Institute for Reproductive Medicine and Science of St. Barnabas in West Orange, N.J. was trying to help infertile women become pregnant.
In each of the 30 cases, something in the mother's egg had prevented her from conceiving naturally. So St. Barnabas researchers extracted material from cells donated by a third woman.
This additional material from the donor's cell somehow allowed the egg to become fertile.
Their first success of having a child born with this cellular transfer technique was published in a medical journal in 1997. But an analysis of the genetic consequences of the method in two babies was only reported in March, in the journal Human Reproduction. DNA tests on two of them show they have a small number of genes that are not from their parents.
The genetic status of the other 28 babies is unknown.
The different genes come from DNA contained in mitochondria — little organs inside cells that create the energy to do life's work. They contain DNA — only about 0.03 percent of the total DNA — so they can make copies of themselves when cells divide. The other 99.97 percent of a cell's DNA comes from the nucleus and the 23 pairs of chromosomes.
A number of scientists question the ethics of the experiment. For the first time, they say, it has been confirmed that children have been born with genetic alterations.