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).

[Characteristics of IGF-II gene imprinting in twin placentas].

Objective: To compare insulin-like growth factor II (IGF-II) gene imprinting in twin placentas with singleton ones and to determine whether imprinting was influenced by assisted reproductive technology, zygosity and fetal sex.

Methods: One hundred and sixty cases of twin placentas and 42 cases of singleton ones were recruited. Allele-specific IGF-II expression was determined by reverse transcription-PCR combined with analysis of an Apa I-sensitive restriction fragment length polymorphism.

[Perinatal outcome of discordant twin pregnancies].

Objective: To discuss peripartum obstetrics events and perinatal outcomes of discordant twin pregnancies.

Methods: Discordant growth was defined as the intrapair difference in birth weight more than 20%. Ninety-six discordant twin pregnancies (observed group) and 349 concordant ones (control group) were compared in pregnant complications and perinatal outcomes.