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Lihui Li - One of the best experts on this subject based on the ideXlab platform.
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chromosomal localization of genes conferring desirable agronomic traits from agropyron cristatum chromosome 1p
PLOS ONE, 2017Co-Authors: Qingfeng Li, Jinpeng Zhang, Yuqing Lu, Xinming Yang, Xiuquan Li, Lihui LiAbstract:Agropyron cristatum (L.) Gaertn. (2n = 4x = 28, PPPP), a wild relative of common wheat, possesses many potentially valuable genes for wheat breeding. To transfer these genes into wheat, a series of wheat-A. cristatum derivatives have been obtained in our laboratory. In this study, a wheat-A. cristatum derivative II-3-1 was obtained, which was proven to contain a 1P (1A) disomic substitution and 2P disomic addition line with 40 wheat chromosomes and two pairs of A. cristatum chromosomes by genomic in situ hybridization (GISH) and molecular markers analysis. By further backcrossing with the wheat parent Fukuhokomugi (Fukuho) and self-fertilization, three different lines were separated from II-3-1, including wheat-A. cristatum 1P disomic addition line II-3-1a, 2P disomic addition line II-3-1b and 1P (1A) disomic substitution line II-3-1c. Because 2P addition line had been reported before, we aimed to investigate 1P disomic addition line II-3-1a and wheat-A. cristatum 1P (1A) disomic substitution line II-3-1c. Analysis of different genetic populations demonstrated that 1P chromosome harbored multiple agronomic traits, such as elevated spike length, increased tillering ability, reduced plant height and spikelet density. Besides, bristles on the glume ridges as an important morphological marker was located on 1P chromosome. Therefore, the novel 1P addition and substitution lines will be used as important genetic materials to widen the genetic resources of wheat.
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chromosomal localization of genes conferring desirable agronomic traits from wheat agropyron cristatum disomic addition line 5113
PLOS ONE, 2016Co-Authors: Qingfeng Li, Jinpeng Zhang, Yuqing Lu, Xinming Yang, Xiuquan Li, Yajun Xi, Lihui LiAbstract:Creation of wheat-alien disomic addition lines and localization of desirable genes on alien chromosomes are important for utilization of these genes in genetic improvement of common wheat. In this study, wheat-Agropyron cristatum derivative line 5113 was characterized by genomic in situ hybridization (GISH) and specific-locus amplified fragment sequencing (SLAF-seq), and was demonstrated to be a novel wheat-A. cristatum disomic 6P addition line. Compared with its parent Fukuhokomugi (Fukuho), 5113 displayed multiple elite agronomic traits, including higher uppermost internode/plant height ratio, larger flag leaf, longer spike length, elevated grain number per spike and spikelet number per spike, more kernel number in the middle spikelet, more fertile tiller number per plant, and enhanced resistance to powdery mildew and leaf rust. Genes conferring these elite traits were localized on the A. cristatum 6P chromosome by using SLAF-seq markers and biparental populations (F1, BC1F1 and BC1F2 populations) produced from the crosses between Fukuho and 5113. Taken together, chromosomal localization of these desirable genes will facilitate transferring of high-yield and high-resistance genes from A. cristatum into common wheat, and serve as the foundation for the utilization of 5113 in wheat breeding.
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production and identification of wheat agropyron cristatum 2p translocation lines
PLOS ONE, 2016Co-Authors: Huanhuan Li, Jinpeng Zhang, Liqiang Song, Mingjie Lv, Lihui LiAbstract:Agropyron cristatum (L.) Gaertn. (2n = 28, PPPP), a wild relative of common wheat, possesses many potentially valuable traits that can be transferred to common wheat through breeding programs. The wheat-A. cristatum disomic addition and translocation lines can be used as bridge materials to introduce alien chromosomal segments to wheat. Wheat-A. cristatum 2P disomic addition line II-9-3 was highly resistant to powdery mildew and leaf rust, which was reported in our previous study. However, some translocation lines induced from II-9-3 have not been reported. In this study, some translocation lines were induced from II-9-3 by 60Co-γ irradiation and gametocidal chromosome 2C and then identified by cytological methods. Forty-nine wheat-A. cristatum translocation lines were obtained and various translcoation types were identified by GISH (genomic in situ hybridization), such as whole-arm, segmental and intercalary translocations. Dual-color FISH (fluorescent in situ hybridization) was applied to identify the wheat chromosomes involved in the translocations, and the results showed that A. cristatum 2P chromosome segments were translocated to the different wheat chromosomes, including 1A, 2A, 3A, 4A, 5A, 6A, 7A, 3B, 5B, 7B, 1D, 4D and 6D. Many different types of wheat-A. cristatum alien translocation lines would be valuable for not only identifying and cloning A. cristatum 2P-related genes and understanding the genetics and breeding effects of the translocation between A. cristatum chromosome 2P and wheat chromosomes, but also providing new germplasm resources for the wheat genetic improvement.
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genetic rearrangements of six wheat agropyron cristatum 6p addition lines revealed by molecular markers
PLOS ONE, 2014Co-Authors: Junji Su, Jinpeng Zhang, Liqiang Song, Xinming Yang, Xiuquan Li, Lihui LiAbstract:Agropyron cristatum (L.) Gaertn. (2n = 4x = 28, PPPP) not only is cultivated as pasture fodder but also could provide many desirable genes for wheat improvement. It is critical to obtain common wheat–A. cristatum alien disomic addition lines to locate the desired genes on the P genome chromosomes. Comparative analysis of the homoeologous relationships between the P genome chromosome and wheat genome chromosomes is a key step in transferring different desirable genes into common wheat and producing the desired alien translocation line while compensating for the loss of wheat chromatin. In this study, six common wheat–A. cristatum disomic addition lines were produced and analyzed by phenotypic examination, genomic in situ hybridization (GISH), SSR markers from the ABD genomes and STS markers from the P genome. Comparative maps, six in total, were generated and demonstrated that all six addition lines belonged to homoeologous group 6. However, chromosome 6P had undergone obvious rearrangements in different addition lines compared with the wheat chromosome, indicating that to obtain a genetic compensating alien translocation line, one should recombine alien chromosomal regions with homoeologous wheat chromosomes. Indeed, these addition lines were classified into four types based on the comparative mapping: 6PI, 6PII, 6PIII, and 6PIV. The different types of chromosome 6P possessed different desirable genes. For example, the 6PI type, containing three addition lines, carried genes conferring high numbers of kernels per spike and resistance to powdery mildew, important traits for wheat improvement. These results may prove valuable for promoting the development of conventional chromosome engineering techniques toward molecular chromosome engineering.
Nagy, Gyula Richárd - One of the best experts on this subject based on the ideXlab platform.
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A terhességet megelőzően alkalmazott hosszabb távú orális fogamzásgátlás mint a magzati 21-es triszómia lehetséges kockázatcsökkentő tényezője idős anyai életkorban vállalt terhességben = Longer oral contraception history as a possible preventive factor against fetal trisomy 21 in advanced maternal age pregnancies
'Akademiai Kiado Zrt.', 2018Co-Authors: Horányi Dániel, Abay, Lilla Éva, Győrffy Alázs, Nagy, Gyula RichárdAbstract:Abstract: 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
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A terhességet megelőzően alkalmazott hosszabb távú orális fogamzásgátlás mint a magzati 21-es triszómia lehetséges kockázatcsökkentő tényezője idős anyai életkorban vállalt terhességben = Longer oral contraception history as a possible preventive factor against fetal trisomy 21 in advanced maternal age pregnancies
'Akademiai Kiado Zrt.', 2018Co-Authors: Horányi Dániel, Abay, Lilla Éva, Győrffy Alázs, Nagy, Gyula RichárdAbstract:Absztrakt: A Down-szindróma a leggyakrabban előforduló autoszomális kromoszóma-rendellenesség. A klasszikus értelmezés szerint a meiosis során létrejövő nondiszjunkció következménye. Előfordulása idősebb anyai életkorban gyakoribb. A genetikai rendellenesség kórélettana az intenzív kutatások ellenére sem teljesen tisztázott. Az újabb kutatások szerint egy másfajta mechanizmus állhat a 21-es triszómia hátterében, mint amilyet eddig gondoltunk. A petefészekmozaicizmus-modell alapján a 21-es triszómia (vagy bármely gyakori triszómia) a kromoszóma praemeioticus mitózisban bekövetkező szegregációs hibájára vezethető vissza. A meiosisba lépő örökítősejt tehát már egy eleve triszómiás petesejt lesz, melynek így a későbbiekben a szükségszerű (úgynevezett „szekunder”) nondiszjunkciója zajlik. A triszómiás petesejtek érésükben lemaradni látszanak a diszómiás (azaz normális) petesejtekhez képest. Az idő előrehaladtával a petefészekben relatíve felhalmozódnak: a triszómiás/diszómiás petesejtek aránya kedvezőtlenebb lesz előrehaladott anyai életkorban. Ha gátoljuk az ovulációt – bár az apoptózis miatt a petesejtek száma továbbra is csökkenni fog –, feltételezhető, hogy a triszómiás/diszómiás petesejtek aránya nem romlik, idősebb anyai életkorban is kedvezőbb marad. Összefoglaló közleményünkben – korábbi adataink bemutatásával és kiegészítésével – arra szeretnénk rámutatni, hogy a petefészekmozaicizmus-modell alapján idősebb anyai életkorban vállalt terhesség esetén előnyös lehet az anamnézisben szereplő hosszabb távú orális fogamzásgátlás. Orv Hetil. 2018; 159(28): 1146–1152. | Abstract: 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
Stuart H Orkin - One of the best experts on this subject based on the ideXlab platform.
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downregulation of endothelin receptor b contributes to defective b cell lymphopoiesis in trisomy 21 pluripotent stem cells
Scientific Reports, 2018Co-Authors: Glenn A Maclean, Jennifer Mceldoon, Jialiang Huang, Jeremy Allred, Matthew C Canver, Stuart H OrkinAbstract:Individuals with Trisomy 21 (T21) exhibit numerous hematological abnormalities, including reductions in numbers of circulating B and T lymphocytes. To elucidate molecular mechanisms underlying these phenotypes, we differentiated human isogenic disomic and trisomic pluripotent cells, and observed that trisomic cells showed defects in B cell, but not T cell differentiation. Global gene expression of differentiated, trisomic B cells revealed reduced expression of genes encoding endothelin signaling components, namely the Endothelin Receptor B (EDNRB), and its ligand Endothelin1 (EDN1). Depletion of EDNRB mRNA in cord blood-derived CD34+ cells led to defective B cell differentiation, supporting a hypothesis that low EDNRB expression in T21 contributes to intrinsic lymphoid defects. Further evidence for the role of the EDNRB pathway in B cell differentiation was obtained through CRISPR/Cas9 gene targeting in disomic and trisomic iPS cells. Knockout of EDNRB in both cell backgrounds reduced the capacity for B cell differentiation. Collectively, this work identifies downregulation of EDNRB as a causative factor for impaired B lymphocyte generation in trisomic cells, which may contribute to defects in immune function associated with T21. Furthermore, a novel role for endothelin signaling in regulation of B cell development has been identified.
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downregulation of endothelin receptor b contributes to defective b cell lymphopoiesis in trisomy 21 pluripotent stem cells
Scientific Reports, 2018Co-Authors: Glenn A Maclean, Jennifer Mceldoon, Jialiang Huang, Jeremy Allred, Matthew C Canver, Stuart H OrkinAbstract:Individuals with Trisomy 21 (T21) exhibit numerous hematological abnormalities, including reductions in numbers of circulating B and T lymphocytes. To elucidate molecular mechanisms underlying these phenotypes, we differentiated human isogenic disomic and trisomic pluripotent cells, and observed that trisomic cells showed defects in B cell, but not T cell differentiation. Global gene expression of differentiated, trisomic B cells revealed reduced expression of genes encoding endothelin signaling components, namely the Endothelin Receptor B (EDNRB), and its ligand Endothelin1 (EDN1). Depletion of EDNRB mRNA in cord blood-derived CD34+ cells led to defective B cell differentiation, supporting a hypothesis that low EDNRB expression in T21 contributes to intrinsic lymphoid defects. Further evidence for the role of the EDNRB pathway in B cell differentiation was obtained through CRISPR/Cas9 gene targeting in disomic and trisomic iPS cells. Knockout of EDNRB in both cell backgrounds reduced the capacity for B cell differentiation. Collectively, this work identifies downregulation of EDNRB as a causative factor for impaired B lymphocyte generation in trisomic cells, which may contribute to defects in immune function associated with T21. Furthermore, a novel role for endothelin signaling in regulation of B cell development has been identified.
Jinpeng Zhang - One of the best experts on this subject based on the ideXlab platform.
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chromosomal localization of genes conferring desirable agronomic traits from agropyron cristatum chromosome 1p
PLOS ONE, 2017Co-Authors: Qingfeng Li, Jinpeng Zhang, Yuqing Lu, Xinming Yang, Xiuquan Li, Lihui LiAbstract:Agropyron cristatum (L.) Gaertn. (2n = 4x = 28, PPPP), a wild relative of common wheat, possesses many potentially valuable genes for wheat breeding. To transfer these genes into wheat, a series of wheat-A. cristatum derivatives have been obtained in our laboratory. In this study, a wheat-A. cristatum derivative II-3-1 was obtained, which was proven to contain a 1P (1A) disomic substitution and 2P disomic addition line with 40 wheat chromosomes and two pairs of A. cristatum chromosomes by genomic in situ hybridization (GISH) and molecular markers analysis. By further backcrossing with the wheat parent Fukuhokomugi (Fukuho) and self-fertilization, three different lines were separated from II-3-1, including wheat-A. cristatum 1P disomic addition line II-3-1a, 2P disomic addition line II-3-1b and 1P (1A) disomic substitution line II-3-1c. Because 2P addition line had been reported before, we aimed to investigate 1P disomic addition line II-3-1a and wheat-A. cristatum 1P (1A) disomic substitution line II-3-1c. Analysis of different genetic populations demonstrated that 1P chromosome harbored multiple agronomic traits, such as elevated spike length, increased tillering ability, reduced plant height and spikelet density. Besides, bristles on the glume ridges as an important morphological marker was located on 1P chromosome. Therefore, the novel 1P addition and substitution lines will be used as important genetic materials to widen the genetic resources of wheat.
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chromosomal localization of genes conferring desirable agronomic traits from wheat agropyron cristatum disomic addition line 5113
PLOS ONE, 2016Co-Authors: Qingfeng Li, Jinpeng Zhang, Yuqing Lu, Xinming Yang, Xiuquan Li, Yajun Xi, Lihui LiAbstract:Creation of wheat-alien disomic addition lines and localization of desirable genes on alien chromosomes are important for utilization of these genes in genetic improvement of common wheat. In this study, wheat-Agropyron cristatum derivative line 5113 was characterized by genomic in situ hybridization (GISH) and specific-locus amplified fragment sequencing (SLAF-seq), and was demonstrated to be a novel wheat-A. cristatum disomic 6P addition line. Compared with its parent Fukuhokomugi (Fukuho), 5113 displayed multiple elite agronomic traits, including higher uppermost internode/plant height ratio, larger flag leaf, longer spike length, elevated grain number per spike and spikelet number per spike, more kernel number in the middle spikelet, more fertile tiller number per plant, and enhanced resistance to powdery mildew and leaf rust. Genes conferring these elite traits were localized on the A. cristatum 6P chromosome by using SLAF-seq markers and biparental populations (F1, BC1F1 and BC1F2 populations) produced from the crosses between Fukuho and 5113. Taken together, chromosomal localization of these desirable genes will facilitate transferring of high-yield and high-resistance genes from A. cristatum into common wheat, and serve as the foundation for the utilization of 5113 in wheat breeding.
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production and identification of wheat agropyron cristatum 2p translocation lines
PLOS ONE, 2016Co-Authors: Huanhuan Li, Jinpeng Zhang, Liqiang Song, Mingjie Lv, Lihui LiAbstract:Agropyron cristatum (L.) Gaertn. (2n = 28, PPPP), a wild relative of common wheat, possesses many potentially valuable traits that can be transferred to common wheat through breeding programs. The wheat-A. cristatum disomic addition and translocation lines can be used as bridge materials to introduce alien chromosomal segments to wheat. Wheat-A. cristatum 2P disomic addition line II-9-3 was highly resistant to powdery mildew and leaf rust, which was reported in our previous study. However, some translocation lines induced from II-9-3 have not been reported. In this study, some translocation lines were induced from II-9-3 by 60Co-γ irradiation and gametocidal chromosome 2C and then identified by cytological methods. Forty-nine wheat-A. cristatum translocation lines were obtained and various translcoation types were identified by GISH (genomic in situ hybridization), such as whole-arm, segmental and intercalary translocations. Dual-color FISH (fluorescent in situ hybridization) was applied to identify the wheat chromosomes involved in the translocations, and the results showed that A. cristatum 2P chromosome segments were translocated to the different wheat chromosomes, including 1A, 2A, 3A, 4A, 5A, 6A, 7A, 3B, 5B, 7B, 1D, 4D and 6D. Many different types of wheat-A. cristatum alien translocation lines would be valuable for not only identifying and cloning A. cristatum 2P-related genes and understanding the genetics and breeding effects of the translocation between A. cristatum chromosome 2P and wheat chromosomes, but also providing new germplasm resources for the wheat genetic improvement.
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genetic rearrangements of six wheat agropyron cristatum 6p addition lines revealed by molecular markers
PLOS ONE, 2014Co-Authors: Junji Su, Jinpeng Zhang, Liqiang Song, Xinming Yang, Xiuquan Li, Lihui LiAbstract:Agropyron cristatum (L.) Gaertn. (2n = 4x = 28, PPPP) not only is cultivated as pasture fodder but also could provide many desirable genes for wheat improvement. It is critical to obtain common wheat–A. cristatum alien disomic addition lines to locate the desired genes on the P genome chromosomes. Comparative analysis of the homoeologous relationships between the P genome chromosome and wheat genome chromosomes is a key step in transferring different desirable genes into common wheat and producing the desired alien translocation line while compensating for the loss of wheat chromatin. In this study, six common wheat–A. cristatum disomic addition lines were produced and analyzed by phenotypic examination, genomic in situ hybridization (GISH), SSR markers from the ABD genomes and STS markers from the P genome. Comparative maps, six in total, were generated and demonstrated that all six addition lines belonged to homoeologous group 6. However, chromosome 6P had undergone obvious rearrangements in different addition lines compared with the wheat chromosome, indicating that to obtain a genetic compensating alien translocation line, one should recombine alien chromosomal regions with homoeologous wheat chromosomes. Indeed, these addition lines were classified into four types based on the comparative mapping: 6PI, 6PII, 6PIII, and 6PIV. The different types of chromosome 6P possessed different desirable genes. For example, the 6PI type, containing three addition lines, carried genes conferring high numbers of kernels per spike and resistance to powdery mildew, important traits for wheat improvement. These results may prove valuable for promoting the development of conventional chromosome engineering techniques toward molecular chromosome engineering.
Horányi Dániel - One of the best experts on this subject based on the ideXlab platform.
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A terhességet megelőzően alkalmazott hosszabb távú orális fogamzásgátlás mint a magzati 21-es triszómia lehetséges kockázatcsökkentő tényezője idős anyai életkorban vállalt terhességben = Longer oral contraception history as a possible preventive factor against fetal trisomy 21 in advanced maternal age pregnancies
'Akademiai Kiado Zrt.', 2018Co-Authors: Horányi Dániel, Abay, Lilla Éva, Győrffy Alázs, Nagy, Gyula RichárdAbstract:Abstract: 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
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A terhességet megelőzően alkalmazott hosszabb távú orális fogamzásgátlás mint a magzati 21-es triszómia lehetséges kockázatcsökkentő tényezője idős anyai életkorban vállalt terhességben = Longer oral contraception history as a possible preventive factor against fetal trisomy 21 in advanced maternal age pregnancies
'Akademiai Kiado Zrt.', 2018Co-Authors: Horányi Dániel, Abay, Lilla Éva, Győrffy Alázs, Nagy, Gyula RichárdAbstract:Absztrakt: A Down-szindróma a leggyakrabban előforduló autoszomális kromoszóma-rendellenesség. A klasszikus értelmezés szerint a meiosis során létrejövő nondiszjunkció következménye. Előfordulása idősebb anyai életkorban gyakoribb. A genetikai rendellenesség kórélettana az intenzív kutatások ellenére sem teljesen tisztázott. Az újabb kutatások szerint egy másfajta mechanizmus állhat a 21-es triszómia hátterében, mint amilyet eddig gondoltunk. A petefészekmozaicizmus-modell alapján a 21-es triszómia (vagy bármely gyakori triszómia) a kromoszóma praemeioticus mitózisban bekövetkező szegregációs hibájára vezethető vissza. A meiosisba lépő örökítősejt tehát már egy eleve triszómiás petesejt lesz, melynek így a későbbiekben a szükségszerű (úgynevezett „szekunder”) nondiszjunkciója zajlik. A triszómiás petesejtek érésükben lemaradni látszanak a diszómiás (azaz normális) petesejtekhez képest. Az idő előrehaladtával a petefészekben relatíve felhalmozódnak: a triszómiás/diszómiás petesejtek aránya kedvezőtlenebb lesz előrehaladott anyai életkorban. Ha gátoljuk az ovulációt – bár az apoptózis miatt a petesejtek száma továbbra is csökkenni fog –, feltételezhető, hogy a triszómiás/diszómiás petesejtek aránya nem romlik, idősebb anyai életkorban is kedvezőbb marad. Összefoglaló közleményünkben – korábbi adataink bemutatásával és kiegészítésével – arra szeretnénk rámutatni, hogy a petefészekmozaicizmus-modell alapján idősebb anyai életkorban vállalt terhesség esetén előnyös lehet az anamnézisben szereplő hosszabb távú orális fogamzásgátlás. Orv Hetil. 2018; 159(28): 1146–1152. | Abstract: 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