نتایج جستجو برای: 21 trisomy
تعداد نتایج: 251021 فیلتر نتایج به سال:
The presence of 47 chromosomes in mongoloids, due to the trisomy of a small acrocentric chromosome in the 21-22 group (Denver system) was demonstrated by Lejeune et al. 1 1 in 1959, and since that time has been confirmed by numerous authors (Beçak 2 ) . The production of this trisomy is explained by a defect in the process by which the homologous chromosomes or sister chromatids should dislocat...
Genetics The presence of a complete or partial third copy of human chromosome 21 (Hsa21) is the cause of DS. Partial copy should include all or part of the long arm of Hsa21.This excess of genetic material leads to a dysregulated expression of certain genes. The functional impact of these changes could be a direct result of the action of the proteins expressed in excess by the Hsa21 genes, or i...
To assess the association between recombination and nondisjunction of chromosome 21, we analyzed cytogenetic and DNA markers in 104 trisomy 21 individuals and their parents. Our DNA marker studies of parental origin were informative in 100 cases, with the overwhelming majority (94) being maternal in origin. This value is significantly higher than the 75%-80% maternal nondisjunction rate typical...
down’s syndrome, or 21 trisomy, is the most common autosomal abnormality, with incidence of 1 per 815 live births in iran. worldwide reports indicate that about 95% are regular trisomy, or nondisjunction, 1% are mosaic and 4% due to translocation. however, these values show a geographical variation. a cytogenetic study of down's syndrome, or trismoy 21, was carried out on 366 cases (202 males a...
OBJECTIVE To determine the value of measuring fetal ear length at 11-14 weeks of gestation in screening for chromosomal defects. METHODS The fetal ear length was measured in 450 fetuses immediately before chorionic villus sampling for karyotyping at 11-14 weeks of gestation. RESULTS The median gestational age was 12 (range, 11-14) weeks. The fetal ear was successfully examined in all cases....
OBJECTIVE The aim of this study is to identify potential biomarkers for fetal trisomy 21 from previous publications using proteomic techniques and examine the potential value of such biomarkers in early screening for this aneuploidy. METHODS This was a case-control study of 25 pregnancies with fetal trisomy 21 and 50 euploid controls undergoing first-trimester screening for aneuploidies by a ...
OBJECTIVE To report the performance of massively parallel sequencing (MPS) based prenatal noninvasive fetal trisomy test based on cell-free DNA sequencing from maternal plasma in a routine clinical setting in China. METHOD The MPS-based test was offered as a prenatal screening test for trisomies 21 and 18 to pregnant women in 49 medical centers over 2 years. A total of 11,263 participants wer...
OBJECTIVES Measurement of the shortening fraction of the left ventricle (SFLV) is an objective way to assess systolic performance. The aim of the study was to compare first trimester SFLV values in euploid fetuses to those in fetuses with trisomy 21. METHODS We measured SFLV in 56 fetuses from 11 weeks to 13 weeks 6 days. The left ventricular diastolic diameter (LVDD) and left ventricular sys...
The syncytiotrophoblast (ST) is one of the major components of the human placenta, as it is involved in feto-maternal exchanges and the secretion of pregnancy-specific hormones. The aim of this study was to elucidate the formation and function of the ST in trisomy 21 (Down's syndrome). We first used the in vitro model of cytotrophoblast differentiation into ST. Cytotrophoblasts were isolated fr...
OBJECTIVES To investigate the potential value of choroid plexus cyst, intracardiac echogenic focus, hydronephrosis and hyperechogenic bowel as markers of trisomy 21 at 11 + 0 to 13 + 6 weeks. METHODS We examined three-dimensional volumes from 228 fetuses with trisomy 21 and 797 chromosomally normal fetuses at 11 + 0 to 13 + 6 weeks of gestation. We looked for choroid plexus cysts with a minim...
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