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Stem Cell Biology: An Overview
Published in Jyoti Ranjan Rout, Rout George Kerry, Abinash Dutta, Biotechnological Advances for Microbiology, Molecular Biology, and Nanotechnology, 2022
Down’s syndrome is caused by an extra copy of chromosome 21. Briggs et al. (2013) have utilized the IPSCS research to identify the molecular networks associated with the pathogenesis of Down’s syndrome. IPSCS have been utilized in the field of neurogenerative disorders like Parkinson’s disease (PD) in which there occurs a loss of dopaminergic neurons of substantia nigra. The treatment of PD had always been a difficult task because the neurons have already been lost by the time the PD gets clinically manifested. Due to this, the mechanism of this disease has not been explored. Nguyen et al. have used IPSCS and studied G2019S mutation in leucine-rich repeat of kinase 2 (LRRK2) gene, which has been reported in sporadic and familial PD cases. Hence, disease modeling using IPSCS research provides an improved understanding of the molecular mechanisms driving a disease.
Prospects for limiting access to prenatal genetic information about Down syndrome in light of the expansion of prenatal genomics
Published in The New Bioethics, 2023
Second, many human traits that have a genetic contribution typically arise out of genetic causes from multiple genetic variants across the genome. Phenotypic differences do not always result from simple deterministic genetic causes. Most cases of Down syndrome are caused by a trisomy of the 21st chromosome. Huntington’s disease is caused by a change within a single gene. But other traits such as height or autism spectrum disorder do not usually have such simple identifiable causes. Prenatal genetic information about these more complex genetic traits will thus likely be presented as probabilities. Probabilistic information can be difficult to interpret and difficult for prospective parents to act on – for example if faced with a decision to continue or to terminate a pregnancy, or to implant a particular embryo through IVF, implant a different embryo, or try another IVF cycle. If presented with the information that a fetus or embryo has, for instance, a 15% chance of developing an undesired trait, it might be difficult to determine whether 15% is a high likelihood or a low likelihood. Prenatal whole genome sequencing could yield a huge amount of probabilistic information about traits that have a genetic contribution. Figuring out what to do with the information and determining whether it is meaningful in light of one’s values and a child’s imagined future, would be a burden placed on prospective parents.
Fluoride and human health: Systematic appraisal of sources, exposures, metabolism, and toxicity
Published in Critical Reviews in Environmental Science and Technology, 2020
Humayun Kabir, Ashok Kumar Gupta, Subhasish Tripathy
The literature has reported some correlation between maternal serum and umbilical cord blood plasma F− levels, thus suggesting that F− may cross the placenta and incorporate into the developing embryo (Gupta, Seth, Gupta, & Gavane, 1993; Malhotra, Tewari, Chawla, Gauba, & Dhall, 1993). Usually, the umbilical cord blood F− level is nearly 60% that in maternal blood serum (Shimonovitz et al., 1995). Consequently, embryos developing with high maternal F− intake are at high risk of F− toxicity. High F− intake shows an adverse developmental effect in experimental animals, but human studies have been mostly inconclusive (Doull et al., 2006). Researchers have reported three types of developmental disorders from excess F− intake: closed spina bifida, sudden infant death, and Down’s syndrome (Doull et al., 2006). Two studies in India have reported an increased risk of closed spina bifida (abnormal opening in bone) in school-aged children consuming drinking water with F− above the permissible limit (Gupta, Gupta, Seth, & Chaturvedi, 1995). However, further well-controlled, extensive studies are required to make conclusions regarding the risk of spina bifida, occulta, and F− exposure. The literature contains much less data on sudden infant death. Down’s syndrome is a genetic disorder in which three copies of chromosome 21 instead of two are present in the embryo, thus resulting in both physical and mental disorders. Three studies before 1970 reported the relationship between down syndrome and fluoridation but were flawed because of improper methodology (Lilienfeld, 1969; Rapaport, 1956, 1963 as cited in Doull et al., 2006). Later, several other studies were unable to replicate Rapaport’s findings. In 1980, Erickson (1980) analyzed a population of more than 250,000 individuals from 44 cities and was unable to confirm Rapaport’s conclusions. Although an ad hoc (1991) committee rejected Rapaport’s report, they recommended study of developmental toxicity at multiple dosage levels (USPHS, 1991). A recent study has systematically reviewed the incidence of Down’s syndrome and water F− levels, but the results were inconclusive (Whiting, McDonagh, & Kleijnen, 2001).