Gene Therapy Could One Day Prevent Facial Birth Defects
Feb. 22, 2000 (Washington) -- Researchers have developed a method to potentially block the development of cleft palate and other forms of facial birth defects by injecting specific gene products, or proteins, during a key time of development. The results, presented at the annual meeting of the American Association for the Advancement of Science, could lead to gene therapy to correct these birth defects in the womb, experts say.
In rare cases a fetus can develop a severe defect of the face and head called holoprosencephaly. The most severe cases develop only one eye in the middle of the forehead and a large snout-like protrusion, known as a proboscis, where the nose should be, says lead researcher Jill Helms, DDS, PhD. Helms is an assistant professor of orthopedic surgery at the University of California, San Francisco.
Most fetuses with this disorder die, but one in 16,000 infants is born with a less severe -- but still devastating -- form of the disorder. These infants have a cleft lip and palate, which can be partially corrected by surgery. Like other facial birth defects, this one is also associated with brain abnormalities.
The researchers knew that pregnant women who received too much vitamin A, such as those taking the acne medicine Accutane (a modified version of vitamin A), were much more likely to give birth to children with this birth defect. Since little was known about the signals that control face and brain development, Helms and her colleagues began searching for an animal that developed a similar disorder.
At first, the researchers faced a problem: They needed an animal in which they could see the effects of various treatments at all stages of development.
The answer was to use chickens. Too little vitamin A also causes birth defects, and the research team noticed that depriving developing chickens of retinoic acid -- a breakdown product of vitamin A -- caused chicks to develop without the front of the brain and without a beak -- the same parts of the head and face that are affected in humans with the disorder.