汉族新生儿脐血中IGF2印迹表达状态的调查

loss of imprinting of IGF2 in cord blood of newborns of Chinese Han population

目的 调查汉族新生儿脐血IGF2印迹表达分布特征，表型特征及相关影响因素。方法 连续抽样收集1010份新生儿脐血进行逆转录聚合酶链反应、限制性酶切片段长度多态性分析IGF2印迹状态，并分析印迹丢失（loss of imprinting，LOI）与妊娠特征、新生儿体格指标以及父母、家族史的关系。结果 IGF2第9外显子Apo Ⅰ位点呈杂合者占42．8％（432／1010），杂合子中LOI占21．6％（66／306）。单表达和LOI组间，母亲的平均年龄，孕周，孕前体重指数，孕期增重，孕中、晚期的血红蛋白、红细胞压积以及其它生化指标检测值无明显差异；父亲大于35岁者LOI增高（P〈0．05，χ^2=4．69）。新生儿体重2500～2999g组中，LOI占6．25％（2／32），显著低于3000g以上组（P〈0．05，χ^2=4．89）。2500g以下和4000g以上组，LOI者产后2h血糖显著下降（P〈0．01，t=7．47、10．9）。结论 汉族新生儿脐血中IGF2印迹丢失占21．6％，LOI对出生体重有一定影响，父亲年龄可能影响LOI表达。

Objective To study the imprinting status of IGF2 and phenotypes of loss of imprinting （LOI） in cord bloed of neonates of Chinese Flan population and to investigate relative factors to LOI. Methods Cord blood of 1010 Chinese Flan newborns were collected and the imprinting status of IGF2 was detected by reverse tranescription-PCR （RT-PCR） and restriction fragment length polymorphism. The relationships between LOI and fetal growth indices, features of parents and grandparents, clinical characteristics were analyzed. Results Of all cases, 42.8% （432/1010） were heterozygons for a polymorphism of Apa Ⅰ site in exon 9 of IGF2, while 21.6%（66/306）displayed IGF2 LOI. Maternal factors including average age, gestational age, BMI pre-pregnancy, weight gain during pregnancy and the level of HB, HCT, and other indices of biochemistry in their second and third trimester were not correlated with LOI expression. However in newborns with fathers older than 35 yrs, 31.7 % （19/60） displayed LOI, which was significantly more common than that in newborns with younger fathers （ P 〈 0. 05,χ^2= 4.69）. There were no difference in birth weight （BW） between normal imprinting and LOI groups. But if the newbom＇s weights were in 2500-2999 g, LOI was 6.25%（2/32）, which was significantly lower than that in 3000 g group （ P 〈 0. 05,χ^2 = 4.89）. In groups with BW 〈 2500 g and 4000 g, the LOI newborn＇ s blood glucose was decreased significantly after 2 hrs （ P 〈 0. 01, t = 7.47 and 10.9）. Conclusion In newborns of Chinese Flan population, 21.6% showed IGF2 LOI in cord blood. IGF2 LOI may have some influences on fetal growth. Paternal age is associated with LOI.