Syndromes Down syndrome

Keywords Receptors, nicotinic Parkinson s disease Alzheimer s disease Schizophrenia Autism Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) CHRNA5 CHRNA3 Nicotine dependence Tourette s syndrome Down syndrome... 

Down syndrome Down syndrome is the leading cause of mental retardation, occurring in about 1 of every 800 live births the mother s age strongly influences its occurrence. Mental and physical problems, including heart and eye defects, are the result of the formation of three chromosomes (trisomy), usually number 21, instead of a pair. 

Microscopically the brains of AzD patients often show neuronal loss and some atrophy, much as in Down Syndrome, as well as widened sulci and narrowed gyri. Since,... 

A number of family mutations of the APP gene on chromosome 21 have been found, generally in early-onset AzD patients in different countries, all of which lead to increased jS-amyloid production. Also chromosome 21 is abnormally trisomic in Down Syndrome and most Down sufferers develop AzD if they reach 40 years. In transgenic mice, expressing familial AzD mutations of APP, the overexpression of APP is accompanied by increased amyloid deposition but whether this is due to the mutation or overexpression of APP is uncertain. Also not all the animals show memory loss and that tends to precede the amyloid disposition. 

P. Kamoun, M.C. Belardinelli, A. Chabli, K. Lallouchi, and B. Chadefaux-Vekemans, Endogenous hydrogen sulfide overproduction in Down syndrome. Am. J. Med. Genet. A 116, 310-311 (2003). 

Important studies were performed by Trush and coworkers [42], who showed the advantages of applying lucigenin-amplified CL for the measurement of superoxide production by mitochondria in unstimulated monocytes and macrophages as well as by isolated mitochondria [43,44]. Later on, these authors have shown that mitochondrial superoxide production measured by lucigenin-amplified CL increased in the liver of rats treated with the promoter of hepatocarcinogenesis ethinyl estradiol [45], in liver from obese mice [46], and in children with Down syndrome [47]. 

Del Bo, R., Comi, G. R, Giorda, R. etal. The 129 codon polymorphism of the prion protein gene influences earlier cognitive performance in Down syndrome subjects. /. Neurol. 250 688-692,2003. 

Masters, C. L., Simms, G., Weinman, N. A., Multhaup, G., McDonald, B. L., and Beyreuther, K. (1985). Amyloid plaque core protein in Alzheimer disease and Down syndrome. Proc. Natl. Acad. Sci. USA 82, 4245—4249. 

The most common form of aneuploidy is trisomy, or the presence of an extra chromosome in each cell. "Tri-" is Greek for "three" people with trisomy have three copies of a particular chromosome in each cell instead of the normal two copies. Down syndrome is an example of a condition caused by trisomy—people with Down syndrome typically have three copies of chromosome 21 in each cell, for a total of 47 chromosomes per cell. 

Although it is possible to inherit some types of chromosomal abnormalities, most chromosomal disorders (such as Down syndrome and Turner syndrome) are not passed from one generation to the next. 

The toxicity of C60 has been found to be related to its ability to cause oxidative stress (Oberdorster, 2004 and Sayes et al., 2005, 2007). However, literature describing the toxicity of C60 is contradictoiy. The first report on C60 cytotoxicity originated from Tsuchiya et al. who found that C60 inhibited cell proliferation and differentiation dose-dependently in mouse midbrain cells treated at -400 pg/ml for six days. Tsuchiya et al. proposed that reactive oxygen species (ROS) contributed to C60 cytotoxicity. The ROS generation and embryo head abnormalities suggested that C60 may contribute to brain and neuronal diseases such as Down syndrome, Alzheimer s, and Parkinson s disease (Tsuchaiya, 1996). The research that... 

Down Syndrome People with Down syndrome have 3 chromosomes, a trisomy, of chromosome 21. The result is lower cognitive ability and physical stature. The disorder also causes affected people to have a higher incidence of heart, intestinal, and thyroid problems. 

D. The couple has an increased risk of producing a child with Down syndrome. 

Down syndrome (choice D) typically is the result of a new mutation. When it is transmitted by an affected female, it acts like a dominant mutation and thus would not be affected by consanguinity. 

Clinical Coirelate Maternal Age, Risk of Down Syndrome, and Prenatal Dia wsis... 

The increased risk of trisomy with advanced maternal age motivates more than half of pregnant women in North America to undergo prenatal diagnosis (most commonly, amniocentesis or chorionic villus sampling, discussed in Oiapter 6). Down syndrome can also be screened by assaying maternal serum levels of a-fetoprotein, chorionic gonadotropin, and unconjugated estriol. This so-called triple screen can detect approximately 70% of fetuses with Down syndrome. 

A 26-year-old woman has produced two children with Down syndrome, and she has also had two miscarriages. Which of the following would be the best explanation ... 

Although the risk for Down syndrome increases if a woman has had a previous child, there is no evidence that the risk increases if a more distant relative, such as a first cousin, is affected (choice A). 

Although there is conclusive evidence for an increased risk of Down syndrome with advanced maternal age, there is little or no evidence for a paternal age effect on Down syndrome risk (choice B),... 

An extra copy of material from chromosome 14 or 18 (choice D) could result in a miscarriage, but neither would produce children with Down syndrome, which is caused by an extra copy of the long arm of chromosome 21. 

This is now a routine part of prenatal care, and it will detect some malformations and genetic diseases (e.g., nearly aU cases of anencephaly, most cases of open spina bifida, some types of reduced stature conditions, many congenital heart defects). However, the sensitivity of ultrasound diagnosis is low for many conditions (e.g., Down syndrome), and it fails to detect many genetic and biochemical abnormalities. 

The cause of Alzheimer s disease is unknown, but genetic factors clearly play a role. One clue supporting this view is provided by the observation that individuals with Down syndrome, a common cause of mental retardation, frequently develop a dementia similar to Alzheimer s disease during early adulthood. Vascular dementia, which is also called multi-infarct dementia, results from the accumulation of tiny strokes. Individually, these strokes or infarcts are too small to cause any noticeable problem, but as they accumulate, they produce deficits similar to Alzheimer s disease. Other neurological diseases such as Parkinson s disease, Pick s disease, and Huntington s disease cause slow deterioration of the brain that ultimately leads to a degenerative dementia. 

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