What is the pathological mechanism of Turner's syndrome?
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It sucks that people say that a Barr Body is an inactivated X-chromosome, because actually there are some genes that remain active on the Barr Body.  They are similar to the genes on the Y-chromosome in males.  Without these minor genes, we will die.  In fact, about 98% of Turner's syndrome affected embryo's spontaneously abort in the fetus.  Most don't live long at all after birth.  The thing is that we aren't sure why without those few genes we die.
82465
Its caused by the gene that causes down syndrome.  They normally will have round faces, small eyes, be short, with poochy abdomines and many other simulariaties to one another.  Hope this helps.  By the way the techincal term for what they look like is mongaloid
296104
Any process resulting in the breakage of chromosomes or the loss or rearrangement of pieces of chromosomes
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There are a couple of ways to get extra chromosomes.  Probably the most common way is related to something called "non-disjunction" during meiosis, the process by which the body makes sex cells.  When the sex cells are being produced, the number of chromosomes are doubled and then get splint into four gametes.  If they don't split up correctly, you can end up with a cell that has either too many or too few chromosomes.  If this sex cell goes on to produce a fetus, it will have either too many or too few chromosomes.
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Don't ride this mom so hard for being concerned about her child's well being.  The fact that the pediatrician has ordered tests rather than offer reassurance says there may be something there.  Like any disease or syndrome, Turner's can present with a spectrum of severity.  There may be some other clues like widely spaced nipples or slight neck webbing in addition to short stature and delay of menarche, that is concerning the physician.  Turner's is an absence of the second sex chromosome, so the person has 45 chromosomes and is referred to as XO, with the O meaning absence of the second X chromosome.  They can live long and meaningful lives, but don't have the capability to reproduce.  There may be slight cognitive impairment or none at all.  Best wishes on this, but even if she has Turner's remember that there are lots of worse things she could be diagnosed with.
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umm, though i'm not sure what the question really says- i think you are asking about genetic diseases involved with chromosome number, if i'm right the following stands, if not then ignore it. \nif you have less or more chromosomes than 46 you will not survive far past fertilization, at least thats what i understand- either that, or you would be a different species- unable to produce a fertile offspring with a human.\n\nHowever there is a lot of confusion around Down's syndrome. This is caused by non-disjunction of chromosomes during meiosis, and creates trisomy genotypes on chromosome 21. \n\nTrisomy and non-disjunction can also occur on chromosome 17- causing another disease, which i have momentarily forgotten the name of. sorry.
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From what I have read, it appears that it is autosomal dominant and is not X-linked as the gene most likely responsible lies on chromosome 1.\nHope this helps
832734
A karyotype can tell two sorts of information to a genetic counselor about an unborn child. First, it can show the sex of the child (XX=girl, XY=boy). Secondly, it can tell the counselor if there are any chromosomal abnormalities with the unborn child. One more common abnormality seen is Down's Syndrome, which occurs from an extra # 13 chromosome. Turner's Syndrome is when there is only one X sex chromosome. Klienfelter's Syndrome occurs when a fetus inherits 2 X and 1 Y sex chromosome (XXY). Patau's Syndrome is an extra # 18 chromosome. These are the sorts of things a karyotype can tell a genetic counselor.\nGood luck with your assignment!
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Chromosome 4 RingChromosome 4 Ring is a rare disorder that is typically characterized by loss (deletion) of genetic material from both ends of the fourth chromosome & joining of the chromosomal ends to form a ring.\n\n \nGeneral Discussion \n\nChromosome 4 Ring is a rare disorder that is typically characterized by loss (deletion) of genetic material from both ends of the 4th chromosome and joining of the chromosomal ends to form a ring. Associated symptoms and findings may vary greatly, depending on the location of lost genetic material and/or other factors. Some affected infants may have a low birth weight; growth retardation; delays in the acquisition of skills requiring the coordination of mental and physical activities (psychomotor retardation); an abnormally small head (microcephaly); a broad, "beaked" nose; and/or various additional physical abnormalities that are present at birth (congenital anomalies). However, cases have also been reported in which Chromosome 4 Ring is primarily associated with growth retardation, with no major physical anomalies and normal psychomotor development. Chromosome 4 Ring is usually caused by spontaneous (de novo) errors very early in the development of the embryo that appear to occur randomly for unknown reasons (sporadically).\n\n.\n\nResources \n\nChildren's Craniofacial Association \n\n13140 Coit Road\n\nSuite 307\n\nDallas, TX 75240\n\nUSA\n\nTel: 2145709099\n\nFax: 2145708811\n\nTel: 8005353643\n\nEmail: csmith@ccakids.com\n\nInternet: http://www.ccakids.com\n\n\n\nMarch of Dimes Birth Defects Foundation\n\n1275 Mamaroneck Avenue\n\nWhite Plains, NY 10605\n\nTel: (914)428-7100\n\nFax: (914)997-4763\n\nTel: (888)663-4637\n\nEmail: Askus@marchofdimes.com\n\nInternet: http://www.marchofdimes.com\n\n\n\nThe Arc (a national organization on mental retardation)\n\n1010 Wayne Ave\n\nSuite 650\n\nSilver Spring, MD 20910\n\nTel: (301)565-3842\n\nFax: (301)565-3843\n\nTel: (800)433-5255\n\nTDD: (817)277-0553\n\nEmail: info@thearc.org\n\nInternet: http://www.thearc.org/
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Fragile X is a serious genetic disorder.  It is caused by mutation of the X chromosome.  The outcome can be significant and debilitating.  It can affect males and females differently.  Males may have enlarged ears, large testicles, long face, and skeletal problems.  This is along with hearing loss, speech issues, and ADD issues as well.  Both will have cognitive delays.  Women have similar physical issues as the men, but usually not as severe.
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Causes\n \nX-linked recessive inheritanceThe fragile X syndrome is a genetic disorder caused by mutation of the FMR1 gene on the X chromosome. Mutation at that site is found in 1 out of about every 4000 males and 1 out of about every 6000 females.\n\nNormally, the FMR1 gene contains between 6 and 53 repeats of the CGG codon (trinucleotide repeats). In people with the fragile X syndrome, the FMR1 allele has over 230 repeats of this codon.\n\nExpansion of the CGG repeating codon to such a degree results in a methylation of that portion of the DNA, effectively silencing the expression of the FMR1 protein.\n\nThis methylation of the FMR1 locus in chromosome band Xq27.3 is believed to result in constriction and fragility of the X chromosome at that point, a phenomenon that gave the syndrome its name.\n\nMutation of the FMR1 gene leads to the transcriptional silencing of the fragile X-mental retardation protein, FMRP. In normal individuals, FMRP binds and facilitates the translation of a number of essential neuronal RNAs. In fragile X patients, however, these RNAs are not translated into proteins. The various sequelae of fragile X syndrome .\n\n[edit]\nTransmission of the Fragile X\nThe diagram (right) of X-linked recessive inheritance is not entirely inappropriate but it markedly oversimplifies the situation and does not provide a sufficient foundation for genetic counseling about the fragile X syndrome.\n\nBecause males normally have only one copy of the X chromosome, those males with significant trinucleotide expansion at the FMR1 locus are symptomatic. They are mentally retarded and may show various physical features of the fragile X syndrome.\n\nFemales have two X chromosomes and thus have double the chance of having a working FMR1 allele. Females carrying one X chromosome with an expanded FMR1 gene can have some signs and symptoms of the disorder or be normal.\n\nMales with the fragile X cannot transmit it to any of their sons (since males contribute a Y chromosome, not an X, to their male offspring.)\n\nFemales carrying one copy of the fragile X can transmit it to their sons or daughters. Sons who receive the fragile X are at high risk for mental retardation. Daughters who receive the fragile X may appear normal or they may be mentally retarded, usually to a lesser degree than boys with the syndrome.\n\nIt can begin at birth
91404
Insulin resistance, excessive androgen production, hypothyroidism, hyperprolactinemia, cushings disease.  I think I read that it is also caused from a genetic mutation Syndrome X.  Not for sure on the last one.
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I don't, but fyi Down's Syndrome is caused by trans-located chromosomes, a.k.a. non-disjunction.  It's likely there are some parents on Y!A with one.
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The 46, XX male syndrome is a rare sex chromosomal disorder in man [1]. It mostly occurs due to unequal crossing over between X and Y chromosomes during meiosis [2]. A 32 year old XX male with normal male phenotype and normal adrenarchal hair pattern, bilateral atrophic testes, normal phallus presented with azoospermia and infertility. The gonadotrophins were elevated. Cytogenetic and molecular analysis using FISH with X and SRY probe showed a 46,XX (SRY negative) chromosomal constitution.\n\nDefinition:\nXX male syndrome occurs when the affected individual appears as a normal male, but has female chromosomes. Two types of XX male syndrome can occur: those with detectable SRY gene and those without detectable SRY (Sex determining region Y). SRY is the main genetic switch for determining that a developing embryo will become male.\n\nDescription:\nXX male syndrome is a condition in which the sex chromosomes of an individual do not agree with the physical sex of the affected person. Normally there are 46 chromosomes, or 23 pairs of chromosomes, in each cell. The first 22 pairs are the same in men and women. The last pair, the sex chromosomes, is two X chromosomes in females (XX) and an X and a Y chromosome in males (XY).\n\nIn XX male syndrome, the person has female chromosomes but male physical features. The majority of persons with XX male syndrome have the Y chromosome gene SRY attached to one of their X chromosomes. The rest of the individuals with XX male syndrome do not have SRY detectable in their cells. Hence, other genes on other chromosomes in the pathway for determining sex must be responsible for their male physical features.\n\nGenetic profile:\nIn XX male syndrome caused by the gene SRY, a translocation between the X chromosome and Y chromosome causes the condition. A translocation occurs when part of one chromosome breaks off and switches places with part of another chromosome. In XX male syndrome, the tip of the Y chromosome that includes SRY is translocated to the X chromosome. As a result, an embryo with XX chromosomes with a translocated SRY gene will develop the physical characteristics of a male. Typically, a piece of the Y chromosome in the pseudoautosomal region exchanges with the tip of the X chromosome. In XX male syndrome, this crossover includes the SRY portion of the Y.\n\nIn individuals with XX male syndrome who do not have an SRY gene detectable in their cells, the cause of the condition is not known. Scientists believe that one or more genes that are involved in the development of the sex of an embryo are mutated or altered and cause physical male characteristics in a chromosomally female person. These genes could be located on the X chromosome or on one of the 22 pairs of autosomes that males and females have in common. As of 2001, no genes have been found to explain the female to male sex reversal in people affected with XX male syndrome who are SRY negative. Approximately 20% of XX males do not have a known cause and are SRY negative. It is thought that SRY is a switch point, and the protein that is made by SRY regulates the activity of one or more genes (likely on an autosomal chromosome) that contribute to sex development. Also there have been some studies that demonstrate autosomal recessive and autosomal dominant inheritance for the XX male.\n\nDemographics:\nXX male syndrome occurs in approximately one in 20,000 to one in 25,000 individuals. The vast majority, about 90%, has SRY detectable in their cells. The remaining 10% are SRY negative, although some research indicates that up to 20% can be SRY negative. XX male syndrome can occur in any ethnic background and usually occurs as a sporadic event, not inherited from the person's mother of father. However, some exceptions of more than one affected family member have been reported.\n\nSigns and symptoms:\n\nSRY positive XX male syndrome\nMales with SRY positive XX male syndrome look like and identify as males. They have normal male physic
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Hi there...Wanna read more...please follow the link in the "Sources Box". ;)\n\nHeart Disease:\nMarfan Syndrome\n\nMarfan syndrome is an inherited disease that affects the connective tissue. Connective tissue is the most abundant tissue in the body and is a vital component to supporting the body's organs. Its primary purpose is to hold the body together and provide a framework for growth and development. It provides the strength and support to tendons, cartilage, heart valves and many other parts of the body, as well as strength and elasticity to the blood vessels. \n\nFor people with Marfan syndrome, the chemical makeup of the connective tissue isn't normal and as a result is not as strong as it should be.\n\nBecause connective tissue is found throughout the body, Marfan syndrome can affect many parts, including the bones, eyes, heart and blood vessels, nervous system, skin and lungs. \n\nWhat Causes Marfan Syndrome?\n\nMarfan syndrome is caused by a defect in the gene that encodes the structure of fibrillin and the elastic fibers, major components of connective tissue that appear to contribute to its strength and elasticity.\n\nIn most cases, Marfan syndrome is inherited. The pattern is called "autosomal dominant," meaning it occurs equally in men and women and can be inherited from just one parent with the disorder. People with Marfan syndrome have a 50% chance of passing along the disorder to their children. In rare cases, a new gene defect occurs due to an unknown cause. Marfan syndrome is also referred to as a "variable expression" genetic disorder, since everyone with Marfan syndrome has the same defective gene, but not everyone experiences the same symptoms to the same degree.\n\nMarfan syndrome is present at birth. However, the condition may not be diagnosed until adolescence or young adulthood. It is fairly common, affecting 1 in 5,000 Americans. It is found in people of all races and ethnic backgrounds. \n\nWhat Are the Signs of Marfan Syndrome? \n\nSometimes Marfan syndrome is so mild, few, if any, symptoms occur. In most cases, the disease progresses with age and symptoms become noticeable as the changes in connective tissue occur. \n\nOn the outside, people with Marfan syndrome are often very tall and thin. Their arms, legs, fingers and toes may seem out of proportion, too long for the rest of their body. Their spine may be curved and their breastbone (sternum) may either stick out or be indented inward. Their joints may be weak and easily become dislocated. Often, people with Marfan syndrome have a long, narrow face and the roof of the mouth may be higher than normal, causing the teeth to be crowded. More than half of all people with Marfan syndrome have eye problems.\n\nInternally, many changes occur within the body structures due to the abnormal connective tissue. About 90% of people with Marfan syndrome develop changes in their heart and blood vessels:
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gonosomes.    which are the sex chromosomes ! Hope this is it !! :o)
8297
Down syndrome is caused by trisomy of chromosome 21, that is, an additional chromosome in what should be a pair. This happens when the separation of homologous chromosomes during meiosis is incomplete. Meiosis occurs during gametogenesis, thus if it goes wrong, the resulting gametes will be either one chromosome short or will have one too many chromosomes. If the gamete with 24 chromosomes (23 normal + 1 additional 21) achieves fertilization with a normal gamete, the zigote will have 3 copies of chromosome 21 and will develop into an individual with Down Syndrome. \nSometimes only part of the information in chromosome 21 is repeated, thus there are various "degrees" of development of the syndrome.