Genetic Testing and Modified Diets May Save Babies Born With Genetic Defect Study Shows

June 16, 1999

Genetic testing and dietary modification may save the lives of children born with a defect in the gene controlling fatty acid breakdown, a Wake Forest University Baptist Medical Center physician reported in the June 3 issue of the New England Journal of Medicine.

Jamal A. Ibdah, M.D., Ph.D., assistant professor of internal medicine (gastroenterology), said screening women who develop a type of liver disease late in pregnancy — and their newborns — for the genetic defect could be lifesaving for the newborn.

Ibdah and his colleagues identified the genetic defect in 24 infants or toddlers who had come in with liver, heart or muscular abnormalities suggestive of defects in the body''s use of fatty acids — which ordinarily are used to supply energy and for other essential functions. Eight of the infants died — seven almost immediately and the other died 18 months later, despite treatment.

"The remaining 16 patients are alive and are currently being treated with dietary modification," Ibdah said. "Eight of the surviving children are now older than 5 years and attending school."

The key to survival was a change in the diets of the affected children. "Dietary treatment in these and other fatty acid oxidation disorders dramatically reduces morbidity and mortality."

Ibdah said for infants with the genetic defect, special formulas are available that both reduce the amount of fat and change the types of fat that the babies get. Older children must follow a special diet that accomplishes the same thing.

He said family histories showed previously unexplained sudden deaths in six siblings.

"The major finding in our study is that of the 24 mothers, 15 developed severe liver disease while carrying the babies," said Ibdah.

The research team speculates that the genetic defect in the fetus causes an accumulation of products of fatty acids produced by the fetus or the placenta that are particularly toxic to the liver of the mother. Further, they said this effect may be exaggerated by the decreased ability of the mother to use fatty acids for energy during pregnancy.

Ibdah said one of the liver disorders, called acute fatty liver of pregnancy, "is a devastating disorder associated with substantial maternal and neonatal morbidity and mortality."

He said the disease occurs in roughly one in every 14,000 pregnancies, and the mortality rate for the mother and babies ranges from 10 to 50 percent.

Some women develop a different, but apparently related disorder, which doctors call HELLP [Hemolysis, Elevated Liver enzymes and Low Platelets]. HELLP is a more common maternal illness of late pregnancy, occurring in about one in every 200 pregnancies, Between 1 and 3 percent of the mothers die, while between 20 and 35 percent of the infants die in severe cases.

Of the 15 mothers with liver disease in the study, 11 had acute fatty liver, while four had HELLP.

Testing those mothers, their partners and the infants for the defect soon after birth could mean early diagnosis in the infant before problems can develop, essentially avoiding the complications. "We can save the babies by screening for this genetic defect," Ibdah said. "Screening can also help physicians better advise these mothers regarding the risk of future pregnancies."

The genetic test is available at the Wake Forest University Baptist Medical Center and at some other academic medical centers

The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases and the American Digestive Health Foundation. The team also included investigators from the University of Texas Southwestern Medical Center in Dallas, the Mayo Clinic and the Washington University School of Medicine in St. Louis.


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