Seven placental transcripts characterize HELLP-syndrome

Area of Science:

• Obstetrics and Gynecology
• Molecular Biology
• Genetics

Background:

• Gestational hypertensive diseases, including early-onset preeclampsia (PE) and Hemolysis, Elevated Liver enzymes and Low platelets (HELLP) syndrome, are major causes of maternal and perinatal mortality.
• The human placenta plays a critical role in the development of these conditions, but the underlying molecular mechanisms remain incompletely understood.

Purpose of the Study:

• To investigate differences in placental gene expression between normotensive pregnant women and those with PE and HELLP syndrome.
• To identify a distinct molecular signature for HELLP syndrome within placental tissue.
• To determine if HELLP syndrome is a variant of PE or a separate disease entity based on placental gene expression.

Main Methods:

• Serial Analysis of Gene Expression (SAGE) profiling to compare placental tissue from control, HELLP, and PE pregnancies.
• Quantitative real-time PCR (sqPCR) to validate the expression levels of differentially expressed transcripts.
• Nearest centroid classification to identify a molecular signature and assess its discriminatory power.

Main Results:

• Comparison of SAGE profiles identified 404 differentially expressed transcripts between control and HELLP/PE placentas.
• A specific molecular signature for HELLP syndrome was identified, characterized by upregulated expression of FLT1, LEP, PAPPA2, WWTR1 and downregulated expression of CTNNAL, GSTP1, S100A8.
• This signature discriminated HELLP placentas from control and PE placentas with a 24% misclassification rate, independent of risk factors.

Conclusions:

• The identified placental molecular signature suggests that HELLP syndrome is a distinct disease entity, not merely a variant of PE.
• These findings provide a foundation for further molecular analysis and understanding of PE and HELLP syndrome.
• The multigenic nature of these disorders is highlighted by the diverse molecular pathways implicated.