Understanding genetics and genetic tests
David M. Luesley, Mark D. Kilby in Obstetrics & Gynaecology, 2016
Chromosomal disorders are very common and are estimated to affect at least 7.5 percent of all conceptions. However, they usually result in a non-viable pregnancy, so the liveborn frequency is 0.6 percent. About 60 percent of early spontaneous miscarriages have a chromosomal abnormality, 5 percent of late spontaneous miscarriages and 4–5 percent of stillbirths. The clinical features that suggest a chromosomal disorder in a child are: multiple congenital anomalies;short stature including IUGR;learning difficulties;microcephaly;dysmorphism.
Developmental Disorders
Jeremy R. Jass in Understanding Pathology, 2020
Congenital malformations have been known to humankind since the dawn of time. Serious malformations are due to a localised error of structural development occurring in the eight weeks following conception. Milder defects (included in Table 10) develop later. One malformation may lead to another and be caused by genetic factors, by environmental factors or by a combination of the two. The genetic causes are classified into chromosomal and single gene disorders. A chromosomal disorder implies an abnormality that can be visualised by the technique of preparing a chromosome spread from a dividing cell and examining the stained chromosomes under a microscope (karyotyping). Abnormalities may include an extra chromosome (e.g. trisomy 21 causing Down’s syndrome), an absent chromosome (e.g. XO causing Turner’s syndrome), deletion of part of a chromosome, inversion of part of a chromosome or a translocation of one part of a chromosome to another. Chromosomal disorders usually arise during gametogenesis and are generally not transmitted since affected individuals either die at birth or are sterile.
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
There are a number of abnormalities of CHROMOSOMES recognized in humans. Some 4% of all recognized pregnancies involve a foetus with a chromosome abnormality. However, most spontaneously terminate and only some 0.5% of live births involve infants with chromosome abnormalities. A proportion of these will be severe enough to limit life, but infants with a number of recognized conditions do survive and enjoy healthy lives. The majority of the cases of chromosome abnormality involve DOWN SYNDROME or TRISOMY 21, but there are many others: see for example FRAGILE x SYNDROME, KLINEFELTER'S SYNDROME (XXY syndrome), PHENYLKETONURIA, XYY SYNDROME, TURNER'S SYNDROME and TRIPLE x SYNDROME (XXX syndrome)
Do steviol glycosides affect the oxidative and genotoxicity parameters in BALB/c mice?
Published in Drug and Chemical Toxicology, 2022
Şemsi Gül Yılmaz, Aslı Uçar, Serkan Yılmaz
Our findings indicated that the SG doses used apparently did not have in vivo genotoxic effects but did exerted weak genotoxicity which is most probably related to the increased oxidative damage. The biochemical data obtained in this study was consistent with the chromosome abnormality results. However, SG had mitogenic effects in all doses. The consumption of stevia is increasing on a daily basis because it is classed as a natural sweetener and considered safe by some researchers and authorities. In addition to this study, which is among the pioneering studies to determine the safety of SG consumption, it is necessary that further investigations are conducted to clarify the reliability of SG compounds, particularly in the field of research on tumor development, and thus determine if the intake of stevia by consumers should be limited or not. Such future investigations should be conducted using different study organisms.
Why classical cytogenetics still matters in acute myeloid leukemia
Published in Expert Review of Hematology, 2020
Vladimir Lj Lazarevic, Bertil Johansson
Thirdly, it is important to take into account that the cytogenetic risk groups have all been defined cytogenetically and that all published outcome data are based on chromosomal analyses. For example, CK AML is defined as three or more unrelated chromosome abnormalities and MK AML corresponds to the presence of one-single autosomal monosomy in association with at least one additional monosomy or structural chromosome abnormality [4]. If other techniques with a higher resolution, such as SNP array and WGS, are applied to detect CK and MK AML, then many more structural chromosome changes will be identified and hence, by necessity, increase the frequencies of these subgroups, unless care is taken to try to deduce which abnormalities ought to have been identified cytogenetically. Thus, cytogenetic definitions cannot be directly applied to WGS, something that has to be resolved before applying WGS for risk stratification.
Perinatal outcomes of pregnancies with prenatally diagnosed foetal congenital heart disease
Published in Journal of Obstetrics and Gynaecology, 2022
Riza Madazlı, Ebru Alıcı Davutoglu, Verda Alpay, Didem Kaymak, Hakan Erenel, Funda Oztunc
In our series of foetal structural CHD, 14.9% of cases were found to have a chromosomal abnormality, an incidence comparable to that in other reports (Körner et al. 1997; Song et al. 2009). Trisomy 21 was the most common chromosomal abnormality and the following anomalies according to the frequency were trisomy 18, 13 and 22q11 microdeletion, consistent with previous data (Perolo et al. 2001; Song et al. 2009; Dolk et al. 2011). Certain foetal CHD are more likely to be associated with chromosomal abnormalities, with the most common chromosome abnormality detected in the AVSD group (%42.3) which is in accordance with the literature (Boldt et al. 2002; Devadasan et al. 2018). For other lesions such as heterotaxy syndrome, TGA and DILV/RV, we did not find a chromosomal abnormality, similar to those reported by Song et al. (2009).
Related Knowledge Centers
- Cell Division
- Genetic Testing
- Karyotype
- Meiosis
- Monosomy
- Chromosome
- Gene
- Mitosis
- Species
- Aneuploidy