Prospective screening for pediatric mitochondrial trifunctional protein defects in pregnancies complicated by liver disease.

Context: Acute fatty liver of pregnancy (AFLP) and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome are serious complications of pregnancy. Studies in families with recessively inherited mitochondrial trifunctional protein defects documented an association between these maternal illnesses and fetal deficiency of long-chain 3-hydroxyacyl coenzyme A dehydrogenase; this enzyme resides in the alpha subunit of the trifunctional protein and catalyzes the third step in long-chain fatty acid beta oxidation.

Objective: To estimate the frequency of fetal long-chain 3-hydroxyacyl coenzyme A dehydrogenase deficiency in pregnancies complicated by AFLP or HELLP syndrome.

Design, Setting, And Subjects: Cohort study in which 108 consecutive blood samples from women who developed AFLP or HELLP syndrome, from their offspring, or from their partners were referred to our laboratory for molecular screening from January 1997 to December 2001. Twenty-seven women had AFLP and 81 had HELLP syndrome. We screened the DNA for mutations in the alpha subunit of the trifunctional protein.

Main Outcome Measure: Presence of mutations that cause 3-hydroxyacyl coenzyme A dehydrogenase deficiency in the offspring.

Results: We detected mutations causing pediatric long-chain 3-hydroxyacyl coenzyme A dehydrogenase deficiency in 5 families (19%) with maternal history of AFLP (95% confidence interval, 9%-54%). The maternal allele carried a prevalent glutamic acid 474 to glutamine (E474Q) mutation. The paternal allele carried the E474Q mutation in 3 families and a stop codon mutation in the other 2 families. Only 1 woman with HELLP syndrome was heterozygous for the E474Q mutation; no mutations were detected in the newborn.

Conclusion: The association between AFLP and the E474Q mutation in the fetus is significant. Screening newborns for this mutation in pregnancies complicated by AFLP could allow early diagnosis and treatment in newborns and genetic counseling and prenatal diagnosis in subsequent pregnancies in affected families.