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Computerized Library System Essaychromosomal aberrations atomic number 18 disruptions in the conventionalism chromosomal content of a mobile ph unrivalled and ar a major(ip) pee of heritable formers in humans, such as plenty syndrome, although most aberrations support little to no effect. Some chromosome defectiveities do non cause disease in carriers, such as translocations, or chromosomal inversions, although they whitethorn lead to a gameer(prenominal) chance of bearing a child with a chromosome disorder. freakish numbers of chromosomes or chromosome sets, called aneuploidy, may be lethal or may give rise to genic disorders. Genetic counseling is offered for families that may carry a chromosome rearrangement. The gain or loss of DNA from chromosomes raft lead to a variety of genetic disorders. Human examples include * Cri du chat, which is caused by the deletion of part of the oblivious arm of chromosome 5. Cri du chat means telephone of the cat in French t he condition was so- recognised because affected babies produce high-pitched cries that sound like those of a cat. Affected individuals have wide-set center fields, a small head and jaw, hash step forward to sober mental health issues, and are very short.* batch syndrome, the most common trisomy, prevalently caused by an special copy of chromosome 21 (trisomy 21). Characteristics include decreased muscle tone, stockier build, asymmetrical skull, slanting eyes and wacky to moderate developmental dis magnate.51 * Edwards syndrome, or trisomy-18, the second-most-common trisomy.citation neededSymptoms include motor retardation, developmental disability and numerous congenital anomalies causation serious health problems. Ninety percent of those affected die in infancy. They have characteristic clutch hands and all overlapping fingers. * Isodicentric 15, to a fault called idic(15), partial tetrasomy 15q, or inverted duplication 15 (inv dup 15). * Jacobsen syndrome, which is v ery idealistic. It is also called the terminal 11q deletion disorder.52Those affected have normal intelligence or mild developmental disability, with light expressive language skills. Most have a exhaust disorder called Paris-Trousseau syndrome. * Klinefelters syndrome (XXY). Men with Klinefelter syndrome are usually sterile, and tend to be taller and have longer arms and legs than their peers. Boys with the syndrome are often shy and quiet, and have a higher incidence of speech delay and dyslexia. Without testosterone treatment, some may develop gynecomastia during puberty. * Patau Syndrome, also called D-Syndrome or trisomy-13. Symptoms are somewhat standardized to those of trisomy-18, without the characteristic folded hand.* Small trim marker chromosome. This means in that location is an unneeded, abnormal chromosome. Features regard on the origin of the spear carrier genetic material. Cat-eye syndrome and isodicentric chromosome 15 syndrome (or Idic15) are both caused by a supernumerary marker chromosome, as is Pallister-Killian syndrome. * Triple-X syndrome (XXX). XXX girls tend to be tall and thin and have a higher incidence of dyslexia. * Turner syndrome (X instead of XX or XY). In Turner syndrome, female sexual characteristics are present but underdeveloped. Females with Turner syndrome often have a short stature, low hairline, abnormal eye features and bone development and a caved-in appearance to the chest. * XYY syndrome. XYY boys are usually taller than their siblings.Like XXY boys and XXX girls, they are more than likely to have learning difficulties. * Wolf-Hirschhorn syndrome, which is caused by partial deletion of the short arm of chromosome 4. It is characterized by severe growth retardation and severe to profound mental health issues. Cri du chat syndrome, also known as chromosome 5p deletion syndrome, 5p minus syndrome or Lejeunes syndrome, is a rare genetic disorder callable to a missing part ofchromosome 5. Its name is a French t erm (cat-cry or call of the cat) referring to the characteristic cat-like cry of affected children. It was basic described by Jrme Lejeune in 1963.1 The condition affects an estimated 1 in 50,000 live births, strikes all ethnicities, and is more common in females by a 43 ratio.Signs and symptomsThe syndrome gets its name from the characteristic cry of affected infants, which is similar to that of a meowing kitten, due to problems with the larynx and nervous system. About 1/3 of children lose the cry by age 2. Other symptoms of cri du chat syndrome may include* provide problems because of difficulty swallowing and sucking.* low birth weight and poor growth.* severe cognitive, speech, and motor delays.* behavioral problems such as hyperactivity, aggression, tantrums, and repetitive movements.* unusual facial features which may change over time.* excessive drooling.* constipation.-GeneticsCri du chat syndrome is due to a partial deletion of the short arm of chromosome number 5, also called 5p monosomy. Approximately 90% of cases results from a sporadic, or randomly-occurring, de novo deletion. The remaining 10-15% are due to unequal segregation of a parental balanced translocation where the 5p monosomy is often accompanied by a trisomic portion of the genome. These individuals may have more severe disease than those with set-apart monosomy of 5p. Most cases involve total loss of the most distant 20-10% of the material on the short arm. fewer than 10% of cases have other rare cytogenetic aberrations (e.g., interstitial deletions, mosaicisms, rings and de novo translocations).The deleted chromosome 5 is parental in origin in about 80% of de novo cases. Loss of a small region in draw 5p15.2 (cri du chat little region) correlates with all the clinical features of the syndrome with the exception of the catlike cry, which maps to band 5p15.3 (catlike critical region). The results suggest that 2 noncontiguous critical regions contain genes involved in this conditi ons etiology. Two genes in these regions, Semaphorine F (SEMA5A) and delta catenin(CTNND2), are potentially involved in cerebral development. The deletion of the telomerase reverse transcriptase (hTERT) gene localized in 5p15.33 may contribute to the phenotypic changes in cri du chat syndrome as well.people with cri du chat syndromeDown syndrome (DS) or Downs syndrome, also known as trisomy 21, is achromosomal condition caused by the presence of all or part of a third copy ofchromosome 21.1 Down syndrome is the most common chromosome abnormality in humans.2 It is typicly associated with a delay in cognitive ability (mental retardation, or MR) and physical growth, and a particular set of facial characteristics.1 The average IQ of young adults with Down syndrome is around 50, compared to children without the condition with an IQ of 100.13 (MR has historically been defined as an IQ below 70.) A braggart(a) proportion of individuals with Down syndrome have a severe degree of intellec tual disability.GeneticsKaryotype for trisomy Down syndrome. visor the three copies of chromosome 21 Down syndrome disorders are based on having too more copies of the genes located on chromosome 21. In general, this leads to an overexpression of the genes.54 Understanding the genes involved may help to target medical treatment to individuals with Down syndrome. It is estimated that chromosome 21 contains 200 to 250 genes.55 Recent research has identified a region of the chromosome that contains the main genes responsible for the pathogenesis of Down syndrome.56 The extra chromosomal material can come about in several distinct ways. A typical human karyotype is designated as 46,XX or 46,XY, indicating 46 chromosomes with an XX arrangement typical of females and 46 chromosomes with an XY arrangement typical of males.57 In 12% of the observed Down syndromes.58 some of the cells in the body are normal and other cells have trisomy 21, this is called mosaic Down syndrome (46,XX/47,XX, +21).5960 Trisomy 21Trisomy 21 (47,XX,+21) is caused by a meiotic nondisjunction event. With nondisjunction, agamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 21 the gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo now has 47 chromosomes, with three copies of chromosome 21. Trisomy 21 is the cause of approximately 95% of observed Down syndromes, with 88% coming from nondisjunction in the agnatic gamete and 8% coming from nondisjunction in the paternal gamete.58 The actual Down syndrome critical region encompasses chromosome bands 21q22.1-q22.3.61Edwards syndrome (also known as Trisomy 18 (T18) or Trisomy E) is a genetic disordercaused by the presence of all or part of an extra 18th chromosome. It is named after John H. Edwards, who first described the syndrome in 1960.1 It is the second most commonautosomal trisomy, after Down syndrome, that carries to term. Edwards syndrome occurs in around one in 6 ,000 live births and around 80 percent of those affected are female.2 The majority of fetuses with the syndrome die before birth.2The incidence increases as the mothers age increases. The syndrome has a very low rate of survival, resulting from heart abnormalities, kidney malformations, and other internal reed organ disorders.Signs and symptomsChildren born with Edwards syndrome may have some or all of the following characteristics kidney malformations, structural heart defects at birth (i.e., ventricular septal defect, atrial septal defect, patent ductus arteriosus), intestines protruding outside the body (omphalocele), esophageal atresia, mental retardation, developmental delays, growth deficiency, feeding difficulties, breathing difficulties, and arthrogryposis (a muscle disorder that causes multiple joint contractures at birth).34 Some physical malformations associated with Edwards syndrome include small head (microcephaly) accompanied by a prominent spine portion of the head (occiput) low-set, malformed ears abnormally small jaw (micrognathia) cleft lip/cleft roof of the mouth upturned nose narrow eyelid folds (palpebral fissures) widely spaced eyes (ocular hypertelorism) drooping of the upper eyelids (ptosis) a short breast bone clenched hands choroid rete cysts underdeveloped thumbs and or nails,absent radius, weave of the second and third toes clubfoot or Rocker bottom feet and in males, undescended testicles. of choroid plexus cysts, which are pockets of fluid on the brain. These are not problematic in themselves, but their presence may be a marker for trisomyGeneticsEdwards syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on the 18th chromosome, either in whole (trisomy 18) or in part (such as due to translocations). The additional chromosome usually occurs beforeconception. The effects of the extra copy vary greatly, depending on the extent of the extra copy, genetic history, and chance. Ed wards syndrome occurs in all human populations but is more prevalent in female offspring.7 A healthy egg and/or sperm cell contains individual chromosomes, each of which contributes to the 23 pairs of chromosomes needed to form a normal cell with a typical human karyotype of 46 chromosomes. numerical errors can arise at either of the two meiotic divisions and cause the failure of a chromosome to discriminate into the daughter cells (nondisjunction). This results in an extra chromosome, making the haploid number 24 sort of than 23. Fertilization of testis or insemination by sperm that contain an extra chromosome results in trisomy, or three copies of a chromosome rather than two.8 Trisomy 18 (47,XX,+18) is caused by a meiotic nondisjunction event. With nondisjunction, a gamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 18 the gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo has 47 chromosomes, with t hree copies of chromosome 18.with edwards syndromeIsodicentric 15, also called idic(15), partial tetrasomy 15q, or inverted duplication 15 (inv dup 15), is a chromosome abnormalityin which a child is born with extra genetic material from chromosome 15. People with idic(15) are typically born with 47 chromosomes in their body cells, instead of the normal 46. The extra chromosome is made up of a piece of chromosome 15 that has been duplicated passim like a mirror image. It is the presence of this extra genetic material that is thought to account for the symptoms seen in some people with idic(15). Individuals with idic(15) have a total of four copies of this chromosome 15 region instead of the usual two copies (1 copy each on the maternal and paternal chromosomes).The extra chromosome is rarely found in mosaic state, i.e. some of the cells carry the marker chromosome. However, mostly because of the markers instability and tendency to be lost during cell division (mitosis), some cells are completely normal with 46 chromosomes. Occasionally, cells may have more than one idic(15), resulting in 48 or 49 chromosomes in all or some of their cells. A similar clinical picture albeit to a milder degree could be expected in individuals that have the extra chromosome 15 material as an interstitial duplication not as a marker chromosome thus having 46 chromosomes.12Signs and symptomsIndividuals with idic(15) have delays in language development and motor skills such as walking or school term up. Other traits may include low muscle tone (hypotonia), seizures, short stature, and mental retardation. Distinctive facial features associated with idic(15) may include epicanthal folds (skin folds at the inner corners of the eyes), a flattened nasal bridge, button nose, and a high arched palate (roof of the mouth). Some individuals with idic(15) also have features of autism, such as problems with communication, social interactions, and repetitive and uninspired behaviors (e.g., lin ing up toys, playing with a toy in the same manner over and over again, hand flapping, rocking back and forth). These are some mild features but with a severe person there may be more such as inability to talk at all.GeneticsGenerally, idic(15) is not acquire it is said to appear de novo in one member of the family, by chance. In most cases, the abnormal chromosome is generated in the mothers germ cells oocytes. This finding is due to ascertainment bias i.e. cases with maternally derived idic(15) usually have clinical findings and close in attention but those with paternally derived idic(15) usually do not. Thus, established cases are usually patients with maternally inherited idic (15).4 . The smallest markers appear to be harmless and they may go undetected. However, if they are large enough to contain a number of important genes, they may result in idic(15) syndrome which is characterized by mental retardation, autism and other neurological symptoms.5 sensation of the regions responsible for the symptoms of idic(15)syndrome is the critical PWS/AS-region named after the Prader-Willi and/or Angelman syndromes.Jacobsen Syndrome, also known as 11q deletion disorder, is a rare congenital disorder resulting from deletion of a terminal region of chromosome 11 that includes band 11q24.1. It can cause intellectual disabilities, a distinctive facial appearance, and a variety of physical problems including heart defects and a bleeding disorder. The syndrome was first identified by Danish physician Petra Jacobsen,1 and is believed to occur in approximately 1 out of every 100,000 births.Possible characteristics* Heart defects* Mild to severe intellectual disabilities* Low-platelets (thrombocytopenia)* Facial/skeletal (dysplasia)* Wide-set eyes caused by trigonocephaly* Folding of the skin near the eye (epicanthus)* Short, upturned nose (anteverted nostrils)* Thin lips that curve inward* Displaced fadeout chin (retrognathia)* Low-set, misshapen ears* Permanent upward curvature of the pinkie and ring fingers (camptodactyly)* Large great toes/ mould toesKlinefelters syndrome, 47, XXY, or XXY syndrome is a condition in which a human has an extra X chromosome. While females have an XX chromosomal makeup, and males an XY, affected individuals have at least two X chromosomes and at least one Y chromosome.1 Because of the extra chromosome, individuals with the condition are usually referred to as XXY Males, or 47, XXY Males.2 This chromosome constitution (karyotype) exists in roughly between 1500 to 11000 live male births34 but many of these people may not show symptoms. The physical traits of the syndrome become more apparent after the plan of attack of puberty, if at all.5 In humans, 47,XXY is the most common sex chromosome aneuploidy in males6 and the second most common condition caused by the presence of extra chromosomes. Other mammals also have the XXY syndrome, including mice.Patau syndrome, also known as trisomy 13 and trisomy D, is a chromos omalabnormality, a syndrome in which a patient has an additional chromosome 13 due to anondisjunction of chromosomes during meiosis. Some are caused by Robertsonian translocations, while others are caused by mosaic Patau syndrome. The extra chromosome 13 disrupts the normal course of development, cause heart and kidney defects, amongst other features characteristic of Patau syndrome.vague Like allnondisjunction conditions (such as Down syndrome and Edwards syndrome), the risk of this syndrome in the offspring increases with maternal age at pregnancy, with about 31 years being the average.1 Patau syndrome affects somewhere between 1 in 10,000 and 1 in 21,700 live births.