Expression of the imprinted IGF2 and H19 genes in the endometrium of cases with unexplained infertility

As genomic imprinting plays a critical role in the development of the placenta, the aim of this study was to detect whether the expression levels of the imprinted genes IGF2 and H19 in the endometrium differ between infertile and fertile women.

Total RNA was extracted from 30 (15 unexplained infertile and 15 fertile) women's endometrial tissue. cDNA was synthesized from total RNAs of each sample. IGF2 and H19 mRNA expression levels were measured quantitatively using the Real Time PCR method. In order to determine the allelic expression of IGF2 and H19, genomic DNA was extracted from endometrial tissues.

When compared with the control group, increased mRNA expression of IGF2 was detected (1.5-fold change, P=0.015) in the unexplained infertility group. In contrast, H19 expression was lower in the infertility group as compared to the control group (4-fold change, P<0.0001). Restriction analysis of cDNA-derived PCR product showed that all patients and controls indicated monoallelic expression of IGF2 and H19.

Our results showed that altered expression of these imprinted genes might affect implantation and that their timely and appropriate activation is important for proper functioning. To understand the molecular epigenetic basis of implantation and placental development, genomic imprinted genes should be further investigated.