title: DNA methylation imprinting errors in spermatogenic cells from maturation arrest azoospermic patients.
abstract: Imprinting errors have been described in spermatozoa from infertile patients with oligozoospermia and azoospermia. However, little is known about methylation of imprinted genes in other spermatogenic cells from azoospermic patients. Therefore, we aimed to evaluate the methylation status of single CpGs located in the differentially methylated regions (DMRs) of two imprinted genes, one paternally (H19) and one maternally (MEST) methylated, in primary spermatocytes of azoospermic patients presenting complete (MAc, n = 7) and incomplete (MAi, n = 8) maturation arrest, as well as in other spermatogenic cells from MAi patients that presented focus of complete spermatogenesis in some seminiferous tubules. We observed H19 imprinting errors in primary spermatocytes from one MAi patient and MEST imprinting errors in one MAi and two MAc patients. Additionally, H19 imprinting errors were observed in elongated spermatids/spermatozoa from one MAi patient. Nevertheless, no statistical differences were found for H19 and MEST global methylation levels (percentage of methylated and unmethylated CpGs, respectively) between patients with complete and incomplete MA and also between MA groups and a control group. These results provide further evidence that imprinting errors occur in spermatogenic cells from patients presenting impaired spermatogenesis, as we and others have previously described in ejaculated and testicular spermatozoa. As paternal imprinting errors can be transmitted to the embryo by the sperm cell, they can provide a possible explanation for poor embryo development and/or low pregnancy rates as correct expression of imprinted genes is crucial for embryo and placental development and function. Therefore, in cases with male factor infertility where unsuccessful in vitro fertilization (IVF) treatments are recurrent, analysis of imprinting marks in spermatozoa might be a useful diagnostic tool.
authors.affiliation: Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal.|I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
authors.forename: P I
authors.initials: PI
authors.lastname: Marques
authors.affiliation: Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal.|I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
authors.forename: S
authors.identifier: 0000-0003-1128-833X
authors.initials: S
authors.lastname: Fernandes
authors.affiliation: Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal.|I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Carvalho
authors.affiliation: Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal.|I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.|Centre for Reproductive Genetics A Barros, Porto, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Barros
authors.affiliation: Centre for Reproductive Genetics A Barros, Porto, Portugal.|Department of Microscopy, Laboratory of Cell Biology, Multidisciplinary Unit for Biomedical Research-UMIB, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Porto, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Sousa
authors.affiliation: Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal.|I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
authors.forename: C J
authors.identifier: 0000-0002-5658-3773
authors.initials: CJ
authors.lastname: Marques
mesh_terms: D053713:Azoospermia / Q000151:congenital* / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D018392:Genomic Imprinting / Q000235:genetics*; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics*; D062085:RNA, Long Noncoding / Q000235:genetics*; D013094:Spermatozoa
chemical_list: C094335:H19 long non-coding RNA; D011506:Proteins; D062085:RNA, Long Noncoding; C103637:mesoderm specific transcript protein
keywords: 
  H19
  ; DNA methylation; MEST/PEG1; azoospermia; epigenetics; genomic imprinting; maturation arrest; spermatogenesis