BOSTON (UPI) -- Drugs that prevent the transmission of
the AIDS virus from infected mothers to their newborns appear to
cause mutations in the babies' DNA at twice the rate seen in
normal children, researchers said Friday.
"We really don't know what this means as far as future problems,
such as the risk of cancer," said Vernon Walker, research
scientist at the Lovelace Respiratory Research Institute,
"However, it does indicate that warnings about future health
problems that were promulgated by the Food and Drug
Administration about use of these drugs in pregnant women were
justified," he told United Press International.
So far, Walker said during a news briefing Friday at the annual
meeting of the American Association for the Advancement of
Science, there are no cases in which cancer related to use of the
drugs has been reported in the children.
Walker said all children are born with a few DNA mutations. In
his study, the average number of mutations among 68 children
unexposed to the antiretroviral drugs used to treat patients with
the virus was 1.3 per million cells.
However among those 71 babies whose mothers took zidovudine or
AZT and/or lamuvidine or 3TC to prevent transmission of the human
immunodeficiency virus, there were an average of 2.6 mutations
per million cells -- twice as many.
In another way of measuring the effect of the drugs on the
newborns, Walker said about 3 percent of the unexposed children
had mutations that indicate an abnormal protein was created by
the DNA damage. Among children born to mothers who took AZT or
both drugs, these types of mutations occurred in 9 percent to 14
percent of the babies.
"Both those figures are significantly greater than the unexposed
children," Walker said.
AZT and 3TC are drugs in the class of nucleoside reverse
transcriptase inhibitors. The drugs integrate into the DNA of the
virus, crippling its ability to reproduce. However, the drugs
also incorporate themselves into the DNA of normal cells and this
change may be transmitted to offspring.
"DNA damage accumulates through a person's lifetime," Walker
said. "These babies whose mothers received AZT and 3TC have the
accumulated DNA mutations one would expect to see in teenagers."
He noted because treatment of pregnant women infected with HIV,
which causes AIDS, prevents transmission of the virus, the
benefit appears to far outweigh the possibility of a risk of
serious disease, such as cancer, down the road. Children who took
AZT in early studies, done to show it could prevent virus
transmission, now are about around 7 years old.
"But," Walker said, "these studies show that the transmission of
these mutations are more than just theoretical."
Stephanie Bird, special assistant to the provost at Massachusetts
Institute of Technology in Cambridge and a health ethicist, said
the findings indicate there is an ethical problem in treating
mothers with the drugs.
She said damage to DNA not only can result in cancer, but might
also cause heart and other developmental abnormalities.
Bird suggested if the it turns out consequences later on are
severe, parents would have to weigh the possibility of not taking
the drugs and then treating children who are born infected with
Walker noted about 25 percent of babies born to untreated mothers
have HIV at birth.
With effective treatment, that number is virtually nil.
"Nobody has focused at all on what these drugs may be doing,"
said Rochelle Diamond, chair of the National Organization of Gay
and Lesbian Scientists and a member of the professional staff at
California Institute of Technology, Pasadena. "Would-be parents
need to know that there is a minimal risk in taking these drugs."