OBJECTIVETo study the imprinting status of IGF2 and phenotypes of loss of imprinting (LOI) in cord blood of neonates of Chinese Han population and to investigate relative factors to LOI.

METHODSCord blood of 1010 Chinese Han newborns were collected and the imprinting status of IGF2 was detected by reverse transcription-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.

RESULTSOf all cases, 42.8% (432/1010) were heterozygous 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, chi square is 4.69). There were no difference in birth weight (BW) between normal imprinting and LOI groups. But if the newborn'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, chi square is 4.89). In groups with BW being less than 2500 g and more than/equal to 4000 g, the LOI newborn's blood glucose was decreased significantly after 2 hrs (P< 0.01, t is 7.47 and 10.9).

CONCLUSIONIn newborns of Chinese Han population, 21.6% showed IGF2 LOI in cord blood. IGF2 LOI may have some influences on fetal growth. Paternal age is associated with LOI.