Browsing by Author "Marjonen, Heidi"

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    In vitro fertilization does not increase the incidence of de novo copy number alterations in fetal and placental lineages
    (Nature Medicine, 2019-11-04) Esteki, Masoud Zamani; Viltrop, Triin; Tšuiko, Olga; Tiirats, Airi; Koel, Mariann; Nõukas, Margit; Žilina, Olga; Teearu, Katre; Marjonen, Heidi; Kahila, Hanna; Meekels, Jeroen; Söderström-Anttila, Viveca; Suikkari, Anne-Maria; Tiitinen, Aila; Mägi, Reedik; Kõks, Sulev; Kaminen-Ahola, Nina; Kurg, Ants; Voet, Thierry; Vermeesch, Joris Robert; Salumets, Andres
    Although chromosomal instability (CIN) is a common phenomenon in cleavage-stage embryogenesis following in vitro fertilization (IVF)1,2,3, its rate in naturally conceived human embryos is unknown. CIN leads to mosaic embryos that contain a combination of genetically normal and abnormal cells, and is significantly higher in in vitro-produced preimplantation embryos as compared to in vivo-conceived preimplantation embryos4. Even though embryos with CIN-derived complex aneuploidies may arrest between the cleavage and blastocyst stages of embryogenesis5,6, a high number of embryos containing abnormal cells can pass this strong selection barrier7,8. However, neither the prevalence nor extent of CIN during prenatal development and at birth, following IVF treatment, is well understood. Here we profiled the genomic landscape of fetal and placental tissues postpartum from both IVF and naturally conceived children, to investigate the prevalence and persistence of large genetic aberrations that probably arose from IVF-related CIN. We demonstrate that CIN is not preserved at later stages of prenatal development, and that de novo numerical aberrations or large structural DNA imbalances occur at similar rates in IVF and naturally conceived live-born neonates. Our findings affirm that human IVF treatment has no detrimental effect on the chromosomal constitution of fetal and placental lineages.
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    rs10732516 polymorphism at the IGF2/H19 locus associates with genotype-specific effects on placental DNA methylation and birth weight of newborns conceived by assisted reproductive technology
    (2018) Marjonen, Heidi; Auvinen, Pauliina; Kahila, Hanna; Tšuiko, Olga; Kõks, Sulev; Tiirats, Airi; Viltrop, Triin; Tuuri, Timo; Söderström-Anttila, Viveca; Suikkari, Anne-Maria; Salumets, Andres; Tiitinen, Aila; Kaminen-Ahola, Nina
    Background Assisted reproductive technology (ART) has been associated with low birth weight of fresh embryo transfer (FRESH) derived and increased birth weight of frozen embryo transfer (FET)-derived newborns. Owing to that, we focused on imprinted insulin-like growth factor 2 (IGF2)/H19 locus known to be important for normal growth. This locus is regulated by H19 imprinting control region (ICR) with seven binding sites for the methylation-sensitive zinc finger regulatory protein (CTCF). A polymorphism rs10732516 G/A in the sixth binding site for CTCF, associates with a genotype-specific trend to the DNA methylation. Due to this association, 62 couples with singleton pregnancies derived from FRESH (44 IVF/18 ICSI), 24 couples from FET (15 IVF/9 ICSI), and 157 couples with spontaneously conceived pregnancies as controls were recruited in Finland and Estonia for genotype-specific examination. DNA methylation levels at the H19 ICR, H19 DMR, and long interspersed nuclear elements in placental tissue were explored by MassARRAY EpiTYPER (n = 122). Allele-specific changes in the methylation level of H19 ICR in placental tissue (n = 26) and white blood cells (WBC, n = 8) were examined by bisulfite sequencing. Newborns’ (n = 243) anthropometrics was analyzed by using international growth standards. Results A consistent trend of genotype-specific decreased methylation level was observed in paternal allele of rs10732516 paternal A/maternal G genotype, but not in paternal G/maternal A genotype, at H19 ICR in ART placentas. This hypomethylation was not detected in WBCs. Also genotype-specific differences in FRESH-derived newborns’ birth weight and head circumference were observed (P = 0.04, P = 0.004, respectively): FRESH-derived newborns with G/G genotype were heavier (P = 0.04) and had larger head circumference (P = 0.002) compared to newborns with A/A genotype. Also, the placental weight and birth weight of controls, FRESH- and FET-derived newborns differed significantly in rs10732516 A/A genotype (P = 0.024, P = 0.006, respectively): the placentas and newborns of FET-derived pregnancies were heavier compared to FRESH-derived pregnancies (P = 0.02, P = 0.004, respectively). Conclusions The observed DNA methylation changes together with the phenotypic findings suggest that rs10732516 polymorphism associates with the effects of ART in a parent-of-origin manner. Therefore, this polymorphism should be considered when the effects of environmental factors on embryonic development are studied.