[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.


RESULTS
Although the incidence of IGF-II imprinting loss was higher in normal twin placentas than in singleton ones (20.6% vs 8.7%), there was no statistical significance. There were no significant differences between twins conceived by assisted reproductive technology and those conceived spontaneously (17.9% vs 24.4%), and between dizygotic and monozygotic twins (22.4% vs 16.7%). The incidence of IGF-II imprinting loss in placenta of female twins was statistically higher than that of male ones (26.4% vs 9.8%).


CONCLUSIONS
The risk of IGF-II gene imprinting loss is higher in female twins and has no relationship with assisted reproductive technology and zygosity.
Luo
Yan-min
YM
Department of Obstetrics and Gynecology, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, 510080 PR China. gzlyanmin@yahoo.com.cn
Fang
Qun
Q
Zhuang
Guang-lun
GL
Liang
Run-cai
RC
Liu
Qiu-ling
QL
D000328:Adult; D005260:Female; D018392:Genomic Imprinting / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008297:Male; D008423:Maternal Age; D010920:Placenta / Q000378:metabolism*; D011110:Polymorphism, Genetic; D011247:Pregnancy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014427:Twins / Q000235:genetics*; D055815:Young Adult
D007335:Insulin-Like Growth Factor II