Screening Certain Infants Can Be Lifesaving, Wake Forest Study Shows
WINSTON-SALEM, N.C. – Investigators at Wake Forest University Baptist Medical Center have demonstrated for the first time that screening newborn infants for a particular genetic defect can be lifesaving when their mothers develop a rare complication of pregnancy.
"It allowed early diagnosis and dietary treatment in affected infants before symptoms appeared," said Jamal A. Ibdah, M.D., Ph.D., the principal investigator, writing in the Nov. 6 issue of the Journal of the American Medical Association.
In a study of 108 women who developed liver problems unique to pregnancy, 27 fit a diagnosis of what is called acute fatty liver of pregnancy. The investigators detected a mutation in infants born to five families, or 19 percent, of the women with acute fatty liver.
"I want the public to know that although this is a rare disorder, the treatment of it is simple and can prevent a death," said Ibdah, associate professor of internal medicine (gastroenterology). "Saving the life of one baby is enough."
The fetus''s genetic defect -- which occurs about once in 40,000 babies -- blocks the body''s use of most fatty acids, the key component in most fat. Fatty acids are ordinarily used to supply energy and for other essential functions. But in these pregnancies, unused fatty acids spill over through the placenta into the mother''s bloodstream and have a toxic effect on the mother''s liver, said Ibdah. (Acute fatty liver of pregnancy also has other causes.)
It is the newborns of these mothers that need to be screened, Ibdah said. "The best time for screening is at birth since the babies manifest the disease at a few months of age."
"The association between acute fatty liver of pregnancy and the mutation is significant," the researchers said. "It is critically important that pediatricians, perinatologists, obstetricians and gastroenterologists be informed of this association." Screening the babies "allows early diagnosis and treatment in the newborn and genetic counseling and prenatal diagnosis in subsequent pregnancies in affected families."
The prenatal diagnosis may show that the baby is completely free of the mutation, or that they have only one copy of the defective gene from either the mother or the father. These babies will not develop the disorder. It is only when the baby has defective genes from both the mother and the father that the disease develops in the mother during pregnancy and in the baby a few months after birth.
Once diagnosed, these babies are placed on special diets that reduce the amount of fat and change the type of fat, which counteracts the effect of the gene mutation.
For instance, these babies can metabolize coconut oil, Ibdah said. These babies also need to avoid fasting.
Ibdah had reported in the New England Journal of Medicine in June 1999 that he and his colleagues had identified the genetic defect in 24 infants or toddlers who had come in with liver, heart or muscular abnormalities that suggested their bodies were not using fatty acids properly. Seven infants died almost immediately and another one about 18 months later. The remaining babies were given the special diet in formulas; older children follow similar diets.
They documented long-term survival of the children on the special diet. Now, said Ibdah, they are reporting that moving in quickly by screening infants born to mothers with acute fatty liver of pregnancy before symptoms develop can be lifesaving -- though children with this defect will need to remain on special diets.
The 108 women in the study were referred from 27 states.
Besides Ibdah, the research team includes Zi Yang, M.D., Jennifer Yamade, M.D. and Yiwen Zhao, all of Wake Forest and Arnold W. Strauss M.D. from the Department of Pediatrics at Vanderbilt University School of Medicine in Nashville.
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