title: Mitochondrial DNA analysis and numerical chromosome condition in human oocytes and polar bodies.
abstract: To investigate the mitochondrial DNA (mtDNA) segregation in human oocytes, the level of heteroplasmy in the three products of meioses, polar bodies (PBs) and corresponding oocytes, was assessed by studying the hypervariable region I (HVRI) of the D-loop region. The DNA from 122 PBs and 51 oocytes from 16 patients was amplified by whole genome amplification (WGA). An aliquot of the WGA product was used to assess aneuploidy, and another aliquot to study mtDNA. The HVRI was amplified and sequenced with an efficiency of 75.4 and 63%, respectively, in PBs, and of 100% in oocytes. The comparison with the mtDNA sequences from blood of the individual donors showed full correspondence of polymorphisms with the matching oocytes, whilst in PBs the degree of concordance dropped to 89.6%. Haplogroups were inferred for all 16 patients. Of the 89 diagnosed PBs from the 13 patients belonging to macrohaplogroup R, 23 were euploid and 66 aneuploid. The incidence of total anomalies was significantly lower in haplogroup H (6.5%) when compared with haplogroups J and T (17.6 and 13.4% respectively; P < 0.001). In haplogroup J, hypoaneuploidy occurred more frequently than hyperaneuploidy. In the three patients belonging to haplogroup N*, 81% of PBs were aneuploid with similar rates of chromosome hypoaneuploidy and hyperaneuploidy. The presence of mtDNA base changes confined to PBs could reflect a selection mechanism against severe mtDNA mutations, while permitting a high evolution rate that could result in bioenergetic diversity. The different susceptibility to aneuploidy by some haplogroups strongly supports this hypothesis.
authors.affiliation: SISMER Reproductive Medicine Unit, V. Mazzini 12, 40138 Bologna, Italy luca.gianaroli@sismer.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Gianaroli
authors.affiliation: Alma Mater Studiorum, University of Bologna, V. Zamboni 33, 40126 Bologna, Italy.
authors.forename: Donata
authors.initials: D
authors.lastname: Luiselli
authors.affiliation: SISMER Reproductive Medicine Unit, V. Mazzini 12, 40138 Bologna, Italy.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Crivello
authors.affiliation: Alma Mater Studiorum, University of Bologna, V. Zamboni 33, 40126 Bologna, Italy.
authors.forename: Martin
authors.initials: M
authors.lastname: Lang
authors.affiliation: SISMER Reproductive Medicine Unit, V. Mazzini 12, 40138 Bologna, Italy.
authors.forename: Anna Pia
authors.initials: AP
authors.lastname: Ferraretti
authors.affiliation: Alma Mater Studiorum, University of Bologna, V. Zamboni 33, 40126 Bologna, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: De Fanti
authors.affiliation: SISMER Reproductive Medicine Unit, V. Mazzini 12, 40138 Bologna, Italy.
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Magli
authors.affiliation: Alma Mater Studiorum, University of Bologna, V. Zamboni 33, 40126 Bologna, Italy European School of Genetic Medicine, V. di Gaibola 16, 40136 Bologna, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Romeo
mesh_terms: D000328:Adult; D002875:Chromosomes; D004272:DNA, Mitochondrial / Q000032:analysis*; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000235:genetics / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D059705:Polar Bodies / Q000378:metabolism*
chemical_list: D004272:DNA, Mitochondrial
keywords: haplogroups; meiosis; mitochondrial DNA; oocyte aneuploidy; polar bodies