Fewer ovulatory cycles, potentially resulting from longer oral contraceptive pill use, was associated with healthy fetal karyotypes among patients of advanced reproductive age.

The International Journal of Gynecology and Obstetrics regrets that, in the above article, an error appeared in the Results section of the Abstract;Instead of "lower estimated ovulation number," "higher estimated ovulation number" should be written. The corrected sentence appears as follows:Shorter mean length of oral contraceptive pill use before trisomic pregnancy (P<0.001) and a higher estimated ovulation number (P=0.012) were identified among patients with pregnancies with fetal trisomies.The International Journal of Gynecology and Obstetrics would like to apologize for any inconvenience caused.

Introduction In 2008, Hultén et al hypothesized that maternal ovarian trisomy 21 mosaicism might be the primary causative factor for fetal Down syndrome. We hypothesize that this theory can be extended to trisomy 13. Material and methods We collected fetal ovarian tissue from seven female fetuses between 16 and 23 gestational weeks, following the termination of the pregnancy for non‐genetic reasons. All procedures were performed with informed consent and ethical approval from the local ethics committee. We used touch preparation techniques from fetal ovarian tissues and an anti‐stromal antigen 3 antibody against the meiosis‐specific stromal antigen 3 protein to differentiate between germ cells, ovarian stromal cells and the cells entering their first meiotic prophase. We used fluorescence in situ hybridization analysis to determine chromosome 13 numbers in each cell. Results We were able to detect a proportion of trisomy 13 cells in all cases. The average incidence of trisomy 13 cells was 2.04% in stromal antigen 3‐positive and 0.91% in the stromal antigen 3‐negative cells. The number of the trisomic cells increased significantly with gestational age (for stromal antigen 3‐positive cells r = 0.93, P = 0.0038, for stromal antigen 3‐negative cells r = 0.85, P = 0.0071). Conclusions This study indicates that besides trisomy 21, the Oocyte Mosaicism Selection model could be extended to trisomy 13 as well. The crucial factor for trisomy 13 seems to be the pre‐meiotic/mitotic trisomy 13 mosaicism, leading to a so‐called secondary meiotic nondisjunction of those oocytes having three copies of chromosome 13.

Down syndrome is the most common autosomal chromosomal abnormality. According to the classical interpretation, it is the result of meiotic nondisjunction. Its occurrence is more common in advanced maternal age. Despite intensive research, pathophysiology of this genetic disorder is not fully understood. According to recent studies, a different kind of mechanism may be found in the background of trisomy 21 than was previously considered. Based on the ovarian mosaicism model, the cause of trisomy 21 (or any common trisomy) is a segregation error of a chromosome in premeiotic mitosis. The cell entering meiosis will be an oocyte with preexisting trisomy, where its (so-called "secondary") nondisjunction is essential. Maturation of the trisomic oocytes appears to fall behind the disomic oocytes, resulting in their relative accumulation in the ovaries as time progresses. The ratio of trisomic/disomic cells becomes less favorable in maternal maturity. If ovulation is inhibited - although the number of oocytes will continue to decline due to apoptosis - it can be assumed that the trisomic/disomic oocyte ratio remains more favorable with the progression of age. In our summary report, presenting and updating our previous data, we would like to propose that - according to ovarian mosaicism model - long-term oral contraception in the anamnesis may be beneficial in pregnancies with advanced maternal age. Orv Hetil. 2018; 159(28): 1146-1152.

Az új generációs szekvenálási eljárások fejlődésével a génszekvenálás új korszaka köszöntött be, amely a noninvazív aneuploidiavizsgálatokat is forradalmasította. Összefoglaló közleményükben a szerzők a teljesebb kép érdekében bizonyos első generációs szekvenálási módszerek leírása után lépésről lépésre ismertetik az egyes új generációs eljárások eltérő elméleti és technikai hátterét. Közleményük második felében a fejlett szekvenálási eljárásokat igénylő, magzati szabad DNS segítségével történő noninvazív praenatalis tesztelésre helyezik a hangsúlyt: a vizsgálat elméleti alapjainak és konkrét technikai kivitelezésének összefoglalása után ismertetik a vizsgálat jelenlegi szerepét és használhatósá-gát az aneuploidiadiagnosztikában. Megállapítják, hogy a noninvazív praenatalis tesztelés a jelenleg leghatékonyabb aneuploidiaszűrő módszer magas kockázatú terhesek esetén, hatékonysága pedig alacsony kockázatú terhességek esetén is tanulmányokkal igazolható. Orv. Hetil., 2015, 156(26), 1041-1048. Kulcsszavak: új generációs szekvenálás, szabad DNS, noninvazív praenatalis tesztelés Next generation sequencing and its applications in non-invasive prenatal testing of aneuploidiesThe development of the new generation sequencing techniques brought a new era in the fi eld of DNA sequencing, that also revolutionized the prenatal screening for aneuploidy. In order to provide a more complete view, the authors describe some fi rst generation methods as well as the theoretical and technical background of the next generation methods. In the second part of this review, the authors focuse on non-invasive prenatal testing, which is a fetal cellfree DNA based method requiring advanced sequencing procedures. After discussing the theoretical and technical background, the authors review current application and utility of non-invasive prenatal testing. They conclude that non-invasive prenatal testing is the most effective screening test in high risk pregnancies and its effi ciency can be justifi ed in studies involving low risk pregnancies as well.Keywords: next generation sequencing, cell-free DNA, non-invasive prenatal testing Babay, L. É., Horányi, D., Rigó, J. Jr., Nagy, Gy. R. [Next generation sequencing and its applications in non-invasive prenatal testing of aneuploidies]. Orv. Hetil., 2015, 156(26), 1041-1048. (Beérkezett: 2015 elfogadva: 2015. május 14.) Rövidítések A = adenin; ATP = adenozin-trifoszfát; C = citozin; CRT = (cyclic reversible termination) ciklikus reverzíbilis termináció; ddNTP = didezoxinukleotid-trifoszfát; DNS = dezoxiribonukleinsav; dNTP = dezoxinukleotid-trifoszfát; FF = magzati frakció; G = guanin; GE = genomegység; MPS = (massively parallel sequencing) masszív párhuzamos szekvenálás; NCV = (normalized chromosome value) normalizált kromoszomális érték; NGS = (next generation sequencing) új generációs szekvenálás; NIPT = nem invazív praenatalis tesztelés; PCR = (polymerase chain reaction) polimeráz lánc-reakció; s-MPS = (shotgun massively parallel sequencing) teljes