Placental regulation of insulin-like growth factor axis in monochorionic twins with chronic twin-twin transfusion syndrome

Imprinting and Promoter Usage of Insulin-Like Growth Factor II in Twin Discordant Placenta

Case reports from infant twins suggest that abnormal genomic imprinting may be one of the important causes of twin discordance, but it is unknown whether abnormal genomic imprinting occurs in the placenta. Therefore, we sought to determine the relationship between the imprinting of insulin-like growth factor II (IGF-II) in placenta and twin discordance. We analyzed the imprinting and promoter usage of IGF-II in placenta of normal twins (T0 group), weight discordance (T1 group), and phenotype discordance (T2 group). We found the incidence of loss of imprinting (LOI) for IGF-II was higher in the T2 group than that in the T0 and T1 groups, while there was no difference between T0 and T1 groups. The transcripts of promoter 3 were lower in the T2 group than in the T0 and T1 groups, and lower in the twin placenta with LOI than in those with normal imprinting. Our findings indicate that the promoter 3 specific LOI of the IGF-II gene may be closely related with phenotype discordance, not weight discordance.

Twin-to-twin transfusion syndrome: an antiangiogenic state?

OBJECTIVE

An imbalanced chronic blood flow between the donor and recipient twin through placental vascular anastomoses is the accepted pathophysiology of twin-to-twin transfusion syndrome (TTTS). Vascular endothelial growth factor receptor-1 (VEGFR-1) mRNA is overexpressed only in the syncytiotrophoblast of the donor twin in some cases of TTTS. This study was conducted to determine maternal plasma concentrations of placental growth factor (PlGF), soluble VEGFR-1, and soluble endoglin (s-Eng) in monochorionic-diamniotic pregnancies with and without TTTS.

STUDY DESIGN

This case-control study included monochorionic-diamniotic pregnancies between 16-26 weeks with and without TTTS. Maternal plasma concentrations of PlGF, sVEGFR-1, and s-Eng were determined with ELISA. A P value < .05 was considered statistically significant.

RESULTS

Patients with TTTS had higher median plasma concentrations of s-Eng (14.8 ng/mL vs 7.8 ng/mL; P < .001) and sVEGFR-1 (6383.1 pg/mL vs 3220.1 pg/mL; P < .001]; and lower median plasma concentrations of PlGF (115.5 pg/mL vs 359.3 pg/mL; P = .002) than those without TTTS.

CONCLUSION

We propose that an antiangiogenic state may be present in some cases of TTTS.