The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
M G Katzjaffe - One of the best experts on this subject based on the ideXlab platform.
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chromosome errors involving large metacentric and Submetacentric Chromosomes are more common in young infertility patients
Fertility and Sterility, 2014Co-Authors: S Mccormick, J Stevens, A Schneiderman, R Smith, W B Schoolcraft, M G KatzjaffeAbstract:OBJECTIVE: Advanced maternal age (AMA) is the most significant risk factor associated with oocyte aneuploidy. Women at 40 years of age have a 50% reduction in fecundity compared to women a decade younger, including a significant increase in pregnancy loss. Chromosome analysis of pre-implantation embryos has revealed that all 23 pairs of Chromosomes are involved in both chromosome gains and losses. The aim of this study was to evaluate the classification of blastocyst chromosome errors in association with maternal age at the time of infertility treatment. DESIGN: Research study. MATERIALS AND METHODS: Infertility patients consented, with IRB approval, to an IVF cyclewith comprehensive chromosome screening (CCS). All embryos were cultured to the blastocyst stage with a trophectoderm biopsy performed for CCS using either SNP microarray or quantitative PCR (RMA-NJ). Aneuploid blastocysts from infertility patients were divided among two groups: Group A1⁄4maternal age<35 years (n1⁄41,091 aneuploid blastocysts) and Group B 1⁄4 maternal age R40 years (n1⁄43,624 aneuploid blastocysts). Chromosome aneuploidy results were analyzed using Chi square test with p value of 0.05 for significance. RESULTS: Predictably, a significant difference was observed for the incidence of aneuploidy relative to AMA (Group A 1⁄4 33% vs. Group B 1⁄473%; P<0.0001). Interestingly, the classification of these chromosome errors was significantly different between the two maternal age groups. AMA infertility patients (Group B) displayed a significant increase in errors (71.2% vs. 63.3% in Group A; p<0.0001) involving small metacentric and acrocentric Chromosomes (13-22) that are observed in clinical pregnancy losses. Conversely, younger infertility patients (Group A) showed a significant increase in errors (16.5% vs. 13.5% in Group B; p1⁄40.01) involving the large metacentric and Submetacentric Chromosomes (1-5), which are not typically observed in miscarriages but predominantly result in implantation failure. CONCLUSION: The frequency and classification of chromosome errors in human blastocysts were significantly different between AMA (R40 years) and younger infertility patients (<35 years), reflecting potential alternative mechanisms associated with aneuploidy generation. These results indicate a clinical advantage of blastocyst aneuploidy screening for younger infertility patients with a history of recurrent implantation failure.
S Mccormick - One of the best experts on this subject based on the ideXlab platform.
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chromosome errors involving large metacentric and Submetacentric Chromosomes are more common in young infertility patients
Fertility and Sterility, 2014Co-Authors: S Mccormick, J Stevens, A Schneiderman, R Smith, W B Schoolcraft, M G KatzjaffeAbstract:OBJECTIVE: Advanced maternal age (AMA) is the most significant risk factor associated with oocyte aneuploidy. Women at 40 years of age have a 50% reduction in fecundity compared to women a decade younger, including a significant increase in pregnancy loss. Chromosome analysis of pre-implantation embryos has revealed that all 23 pairs of Chromosomes are involved in both chromosome gains and losses. The aim of this study was to evaluate the classification of blastocyst chromosome errors in association with maternal age at the time of infertility treatment. DESIGN: Research study. MATERIALS AND METHODS: Infertility patients consented, with IRB approval, to an IVF cyclewith comprehensive chromosome screening (CCS). All embryos were cultured to the blastocyst stage with a trophectoderm biopsy performed for CCS using either SNP microarray or quantitative PCR (RMA-NJ). Aneuploid blastocysts from infertility patients were divided among two groups: Group A1⁄4maternal age<35 years (n1⁄41,091 aneuploid blastocysts) and Group B 1⁄4 maternal age R40 years (n1⁄43,624 aneuploid blastocysts). Chromosome aneuploidy results were analyzed using Chi square test with p value of 0.05 for significance. RESULTS: Predictably, a significant difference was observed for the incidence of aneuploidy relative to AMA (Group A 1⁄4 33% vs. Group B 1⁄473%; P<0.0001). Interestingly, the classification of these chromosome errors was significantly different between the two maternal age groups. AMA infertility patients (Group B) displayed a significant increase in errors (71.2% vs. 63.3% in Group A; p<0.0001) involving small metacentric and acrocentric Chromosomes (13-22) that are observed in clinical pregnancy losses. Conversely, younger infertility patients (Group A) showed a significant increase in errors (16.5% vs. 13.5% in Group B; p1⁄40.01) involving the large metacentric and Submetacentric Chromosomes (1-5), which are not typically observed in miscarriages but predominantly result in implantation failure. CONCLUSION: The frequency and classification of chromosome errors in human blastocysts were significantly different between AMA (R40 years) and younger infertility patients (<35 years), reflecting potential alternative mechanisms associated with aneuploidy generation. These results indicate a clinical advantage of blastocyst aneuploidy screening for younger infertility patients with a history of recurrent implantation failure.
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Chromosome errors involving large metacentric and Submetacentric Chromosomes are more common in young infertility patients
Fertility and Sterility, 2014Co-Authors: S Mccormick, J Stevens, A Schneiderman, R Smith, W B Schoolcraft, Mandy G. Katz-jaffeAbstract:OBJECTIVE: Advanced maternal age (AMA) is the most significant risk factor associated with oocyte aneuploidy. Women at 40 years of age have a 50% reduction in fecundity compared to women a decade younger, including a significant increase in pregnancy loss. Chromosome analysis of pre-implantation embryos has revealed that all 23 pairs of Chromosomes are involved in both chromosome gains and losses. The aim of this study was to evaluate the classification of blastocyst chromosome errors in association with maternal age at the time of infertility treatment. DESIGN: Research study. MATERIALS AND METHODS: Infertility patients consented, with IRB approval, to an IVF cyclewith comprehensive chromosome screening (CCS). All embryos were cultured to the blastocyst stage with a trophectoderm biopsy performed for CCS using either SNP microarray or quantitative PCR (RMA-NJ). Aneuploid blastocysts from infertility patients were divided among two groups: Group A1⁄4maternal age
T. Haaf - One of the best experts on this subject based on the ideXlab platform.
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Species-specific evolution of repeated DNA sequences in great apes
Chromosome Research, 2001Co-Authors: R. Toder, F. Grützner, T. Haaf, E. BauschAbstract:DNA sequencing reveals that the genomes of the human, gorilla and chimpanzee share more than 98% homology. Comparative chromosome painting and gene mapping have demonstrated that only a few rearrangements of a putative ancestral mammalian genome occurred during great ape and human evolution. However, interspecies representational difference analysis (RDA) of the gorilla between human and gorilla revealed gorilla-specific DNA sequences. Cloning and sequencing of gorilla-specific DNA sequences indicate that there are repetitive elements. Gorilla-specific DNA sequences were mapped by fluorescence in-situ hybridization (FISH) to the subcentromeric/centromeric regions of three pairs of gorilla Submetacentric Chromosomes. These sequences could represent either ancient sequences that got lost in other species, such as human and orang-utan, or, more likely, recent sequences which evolved or originated specifically in the gorilla genome.
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Cytogenetics of the genus Leporinus (Pisces, Anostomidae). 1.Karyotype analysis, heterochromatin distribution and sex Chromosomes
Chromosome Research, 1997Co-Authors: M. R. Koehler, T. Haaf, D. Dehm, M. Guttenbach, I. Nanda, W. F. Molina, P. M. Galetti, M. SchmidAbstract:Cytogenetic analyses (Giemsa staining, C-banding, AgNO3 labelling of nucleolus organizer regions (NORs) and staining with base-specific fluorochromes) were performed on the South American fish species Leporinus friderici, L. obtusidens and L. elongatus. The overall karyotypic structure, position of NORs, as well as the amount,distribution and composition of constitutive heterochromatin were determined. Particular attention was given to the highly differentiated ZZ/ZW sex chromosome system of L. obtusidens and L. elongatus. Sharing the apparently ancient macroscopic karyotype of Anostomidae, all three species have 2n=54 meta- or Submetacentric Chromosomes. NORs were found exclusively on chromosome pair 2, which may represent the ancestral NOR-bearing chromosome of the anostomid karyotype. Observed differences in the relative position of NORs along chromosome 2 and variations in the amount and distribution of constitutive heterochromatin throughout the karyotype were most probably caused by heterochromatin-mediated chromosome rearrangements. Detailed analysis of the morphologically similar heteromorphic ZZ/ZW sex Chromosomes of L. obtusidens and L. elongatus allowed detection of differences in the DNA composition of the largely heterochromatic W Chromosomes. However, since these and the W Chromosomes of three other Leporinus species exhibit homologies with respect to their relative size, centromere position and amount and distribution of heterochromatin, it is concluded that they evolved from the same ancestral W chromosome.
M. Schmid - One of the best experts on this subject based on the ideXlab platform.
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Cytogenetics of the genus Leporinus (Pisces, Anostomidae). 1.Karyotype analysis, heterochromatin distribution and sex Chromosomes
Chromosome Research, 1997Co-Authors: M. R. Koehler, T. Haaf, D. Dehm, M. Guttenbach, I. Nanda, W. F. Molina, P. M. Galetti, M. SchmidAbstract:Cytogenetic analyses (Giemsa staining, C-banding, AgNO3 labelling of nucleolus organizer regions (NORs) and staining with base-specific fluorochromes) were performed on the South American fish species Leporinus friderici, L. obtusidens and L. elongatus. The overall karyotypic structure, position of NORs, as well as the amount,distribution and composition of constitutive heterochromatin were determined. Particular attention was given to the highly differentiated ZZ/ZW sex chromosome system of L. obtusidens and L. elongatus. Sharing the apparently ancient macroscopic karyotype of Anostomidae, all three species have 2n=54 meta- or Submetacentric Chromosomes. NORs were found exclusively on chromosome pair 2, which may represent the ancestral NOR-bearing chromosome of the anostomid karyotype. Observed differences in the relative position of NORs along chromosome 2 and variations in the amount and distribution of constitutive heterochromatin throughout the karyotype were most probably caused by heterochromatin-mediated chromosome rearrangements. Detailed analysis of the morphologically similar heteromorphic ZZ/ZW sex Chromosomes of L. obtusidens and L. elongatus allowed detection of differences in the DNA composition of the largely heterochromatic W Chromosomes. However, since these and the W Chromosomes of three other Leporinus species exhibit homologies with respect to their relative size, centromere position and amount and distribution of heterochromatin, it is concluded that they evolved from the same ancestral W chromosome.
R Smith - One of the best experts on this subject based on the ideXlab platform.
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chromosome errors involving large metacentric and Submetacentric Chromosomes are more common in young infertility patients
Fertility and Sterility, 2014Co-Authors: S Mccormick, J Stevens, A Schneiderman, R Smith, W B Schoolcraft, M G KatzjaffeAbstract:OBJECTIVE: Advanced maternal age (AMA) is the most significant risk factor associated with oocyte aneuploidy. Women at 40 years of age have a 50% reduction in fecundity compared to women a decade younger, including a significant increase in pregnancy loss. Chromosome analysis of pre-implantation embryos has revealed that all 23 pairs of Chromosomes are involved in both chromosome gains and losses. The aim of this study was to evaluate the classification of blastocyst chromosome errors in association with maternal age at the time of infertility treatment. DESIGN: Research study. MATERIALS AND METHODS: Infertility patients consented, with IRB approval, to an IVF cyclewith comprehensive chromosome screening (CCS). All embryos were cultured to the blastocyst stage with a trophectoderm biopsy performed for CCS using either SNP microarray or quantitative PCR (RMA-NJ). Aneuploid blastocysts from infertility patients were divided among two groups: Group A1⁄4maternal age<35 years (n1⁄41,091 aneuploid blastocysts) and Group B 1⁄4 maternal age R40 years (n1⁄43,624 aneuploid blastocysts). Chromosome aneuploidy results were analyzed using Chi square test with p value of 0.05 for significance. RESULTS: Predictably, a significant difference was observed for the incidence of aneuploidy relative to AMA (Group A 1⁄4 33% vs. Group B 1⁄473%; P<0.0001). Interestingly, the classification of these chromosome errors was significantly different between the two maternal age groups. AMA infertility patients (Group B) displayed a significant increase in errors (71.2% vs. 63.3% in Group A; p<0.0001) involving small metacentric and acrocentric Chromosomes (13-22) that are observed in clinical pregnancy losses. Conversely, younger infertility patients (Group A) showed a significant increase in errors (16.5% vs. 13.5% in Group B; p1⁄40.01) involving the large metacentric and Submetacentric Chromosomes (1-5), which are not typically observed in miscarriages but predominantly result in implantation failure. CONCLUSION: The frequency and classification of chromosome errors in human blastocysts were significantly different between AMA (R40 years) and younger infertility patients (<35 years), reflecting potential alternative mechanisms associated with aneuploidy generation. These results indicate a clinical advantage of blastocyst aneuploidy screening for younger infertility patients with a history of recurrent implantation failure.
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Chromosome errors involving large metacentric and Submetacentric Chromosomes are more common in young infertility patients
Fertility and Sterility, 2014Co-Authors: S Mccormick, J Stevens, A Schneiderman, R Smith, W B Schoolcraft, Mandy G. Katz-jaffeAbstract:OBJECTIVE: Advanced maternal age (AMA) is the most significant risk factor associated with oocyte aneuploidy. Women at 40 years of age have a 50% reduction in fecundity compared to women a decade younger, including a significant increase in pregnancy loss. Chromosome analysis of pre-implantation embryos has revealed that all 23 pairs of Chromosomes are involved in both chromosome gains and losses. The aim of this study was to evaluate the classification of blastocyst chromosome errors in association with maternal age at the time of infertility treatment. DESIGN: Research study. MATERIALS AND METHODS: Infertility patients consented, with IRB approval, to an IVF cyclewith comprehensive chromosome screening (CCS). All embryos were cultured to the blastocyst stage with a trophectoderm biopsy performed for CCS using either SNP microarray or quantitative PCR (RMA-NJ). Aneuploid blastocysts from infertility patients were divided among two groups: Group A1⁄4maternal age
