Study of DNA methylation patterns of imprinted genes in children born after assisted reproductive technologies reveals no imprinting errors: A pilot study

Abstract

Abstract. Assisted reproductive technology (ART) includingin vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) have been shown to be associated with abnormal genomic imprinting, thus increasing the incidence of imprinting disorders such as Beckwith-Wiedemann syndrome (BWS) and Angelman syndrome (AS) in ART-conceived children. Furthermore, a recent study described abnormal DNA methylation in clinically normal children conceived by ART. However, data from different studies are conflicting or inconclusive. This study examined DNA methylation patterns of multiple imprinted genes in children born after ART to primarily evaluate the impact of ART on genomic imprinting. A total of 101 newborns conceived by ART (40 ICSI and 61 IVF) and 60 naturally conceived newborns were involved in our study. After obtaining the approval of the Institutional Ethics Committee, umbilical cord blood was collected from each infant. Genomic DNA was isolated from each blood sample and treated using sodium bisulfite. Subsequently, using methylation-specific PCR (MS-PCR), we analyzed six differentially methylated regions (DMRs) including KvDMR1, SNRPN, MEST, MEG3, TNDM and XIST. Meanwhile, information regarding twin pregnancies, gestational age, and birth weight of the neonates was documented. None of the cases presented with phenotypic abnormalities. Children conceived by ART were more likely to have low birth weight and to be born before term, compared with children conceived spontaneously. However, 7 months to 3 years of clinical follow-up showed that none of the children had clinical symptoms of any imprinting diseases. Furthermore, the MS-PCR results showed that all 161 children had normal DNA methylation patterns at six DMRs despite the different mode of conception. Our data did not indicate a higher risk of DNA-methylation defects in children born after ART. However, further studies using quantitative methods are needed to confirm these results.

DNA methylation in spermatogenesis and male infertility

“…However, patients with oligoasthenoteratozoospermia with a partial hypomethylation of H19 presented a reduced fertilization rate following intracytoplasmic sperm injection (ICSI). A previous analysis of the methylation status of ICSI infants with a low birth weight revealed hypermethylation at the MEST gene in one of the infants included in the study (119,120).…”

Non-Genetic Inheritance, Fertility and Assisted Reproductive Technologies

“…Again whether these effects of ICSI are a result of genetic or epigenetic factors are unclear. Although a recent study did demonstrate that the dsyregulation in methylation in placentas from ICSI conceived children were more altered compared to IVF children [76], another study determined no increased risk of DNA methylation changes at 6 differentially methylated regions (DMRs) in children conceived by either IVF or ICSI [85]. However, a key limitation to date is the small size of studies which may be underpowered to detect minor differences.…”

12 Heredity in the Epigenetic Era: Are We Facing a Politics of Reproductive Obligations?

“…For example, some studies suggest that the use of the (potentially immature) sperm derived for fertilization by intracellular sperm injection might predispose embryos to a suite of imprinting-related problems such as Beckwith-Weidemann, Angelman's, or Prader-Willi syndromes (Feng et al 2011, Li et al 2011. Despite anecdotal accounts of the aforementioned effects, preliminary studies have failed to reveal imprinting effects upon the small suit of genes analyzed (Zheng et al 2011). However, others have argued that even a brief exposure of egg and sperm to the artificial environment of a Petri dish in a lab incubator engenders subtle risks that will only become apparent when a comprehensive analysis of the entire "epigenome" is attempted (Johnson 2005).…”