Klinefelter’s syndrome (KF) is the most frequent sex chromosome abnormality with an estimated prevalence of 1 in 500 to 1 in 700 newborn males and 1 in 10 in men with azoospermia.While the majority of cases are an XXY genotype, mosaicisms or other aneuploidies can be detected [1]. [30] XXY males may sit up, crawl, and walk later than other infants; they may also struggle in school, both academically and with sports. e) All of the … Therefore one of the cells in meiosis wasn't given an X chromosome, and when sexual reproduction occurred, only one X chromosome present in the embryo. It was found that most fertile individuals with Klinefelter syndrome exhibit mosaicism, in which some cells are normal (46, XY) but others contain the extra chromosome (47, XXY). Nondisjunction occurs when homologous chromosomes (meiosis I) or sister chromatids (meiosis II) fail to separate during meiosis. [21] It has been estimated that 50% of males with Klinefelter syndrome can produce sperm. An XX egg is produced, which when fertilized with a Y sperm, yields an XXY offspring. Down Syndrome. Approximately 15–20%[38] of males with KS may have a mosaic 47,XXY/46,XY constitutional karyotype and varying degrees of spermatogenic failure. Second, our recent study has provided clear and strong evidence that non-disjunctions of sex chromosomes during meiosis I and II of normal testicular 46-XY spermatogonia/primary spermatocytes do not occur in men with non-mosaic Klinefelter’s syndrome (Yamamoto et al., 2002). • This means that the individual has a trisomy (3 – 2lst chromosomes). Click card to see definition . Advanced reproductive assistance is sometimes possible. The primary features are infertility and small poorly functioning testicles. Females have two X chromosomes (46,XX), and males have one X and one Y chromosome (46,XY). Nondisjunction occurs when homologous chromosomes, in this case the … Therefore, nondisjunction accounts for the presence of a trisomy of sex chromosomes. b) Nondisjunction at meiosis II in the mother. Rarer combinations, such as having five X chromosomes, can also occur. Klinefelter: Klinefelters is a genetic disease caused by what is called "nondisjunction". Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. This probably occurs most commonly in meiosis, but it may occur in mitosis to produce a mosaic individual. In nondisjunction during meiosis 1, the homozygous chromosome fail to pair and exchange genetic material during the metaphase plate. Sometimes, symptoms are more evident and may include weaker muscles, greater height, poor coordination, less body hair, breast growth, and less interest in sex. Nondisjunction M M 31 Exercise 5.2 Errors in Meiosis Can Cause Syndromes Errors in Meiosis Lead to Chromosomal Disorders The process that creates gametes in human reproductive organs is called melosis. Additional chromosomal material can contribute to cardiac, neurological, orthopedic, and other anomalies. Fertilizing a double X egg with a normal sperm also produces an XXY offspring (Klinefelter).[34]. An individual with the karyotype 48, XYYY would have how many Barr bodies? ", "Increased mortality in Klinefelter syndrome", "Mortality in patients with Klinefelter syndrome in Britain: a cohort study". [1] Sometimes, symptoms are more prominent and may include weaker muscles, greater height, poor coordination, less body hair, breast growth, and less interest in sex. Key Words: Klinefelter syndrome, spermatogenesis, meiosis, sperm aneuploidy, TESE The 47,XXY karyotype of Klinefelter syndrome spontaneously arises when paired X chromosomes fail to separate (nondisjunction in stage I or II of meiosis, during oogenesis or spermatogenesis). Variants of Klinefelter syndrome (such as 48,XXXY, 49,XXXXY) are much rarer, occurring in 1 in 50,000 to 1 in 85,000 or fewer newborns. [9], The genetic variation is irreversible, thus there is no causal therapy. Nondisjunction Exercise 5.2 Errors in Meiosis Can Cause Syndromes Meiosis 1 Meiosis II Meiosts Y9 n+1 n+1 B ES — nondisjunction during meiosis n-1 Errors in Meiosis Lead to Chromosomal Disorders The process that creates gametes in human reproductive organs is called meiosis. (Fertil Steril 2012;98:253–60. Nondisjunction is the term used to describe when the genetic material is unevenly distributed between the daughter cells during meiosis I or between the haploid gametes at the end of meiosis II, and is the cause for most chromosomal disorders, including Klinefelter's. Klinefelter Syndrome (XXY). Klinefelter’s syndrome is a non-disjunction chromosomal condition of the sex chromosomes. [54], The syndrome was named after American endocrinologist Harry Klinefelter, who in 1942 worked with Fuller Albright and E. C. Reifenstein at Massachusetts General Hospital in Boston, Massachusetts, and first described it in the same year. Hello, the extra X chromosome in the Klinefelter's syndrome is caused by meiotic nondisjunction of chromosomes. This is similar to the maternal case except that after meiosis I, in one cell will be two YY chromosomes while the other cell will be two XX chromosomes. [9] KS is diagnosed by the genetic test known as a karyotype. [17][27] In contrast to these potentially increased risks, rare X-linked recessive conditions are thought to occur less frequently in XXY males than in normal XY males, since these conditions are transmitted by genes on the X chromosome, and people with two X chromosomes are typically only carriers rather than affected by these X-linked recessive conditions. Nondisjunction means that a pair of homologous chromosomes has failed to separate or segregate at anaphase so that both chromosomes of the pair pass to the same daughter cell. [6] About half of affected males have a chance of fathering children with the help of assisted reproductive technology, but this is expensive and not risk free. As such, male cats with calico or tortoiseshell markings are a model organism for KS, because a color gene involved in cat tabby coloration is on the X chromosome. Therefore, nondisjunction accounts for the presence of a trisomy of sex chromosomes. If that doesn't make sense, that's okay. Although, this figure may be underestimated due to different chromosomal mosaicism levels in different tissues. If these eggs are subsequently fertilized with normal sperm, various sex chromosome aneuploidies could occur: Down’s Syndrome or Trisomy 21. (a) Individual; (b) Karyotype. The trisomy pattern of Klinefelter’s can occur through various errors. 23 and 24, During meiosis I in an individual with Klinefelter syndrome, two sex chromosomes will migrate to one daughter cell and one sex chromosome will migrate to the other daughter cell. This happens in XXY males, as well as normal XX females. The Klinefelter-Reifenstein-Albright syndrome. [46], Methods of reproductive medicine, such as intracytoplasmic sperm injection (ICSI) with previously conducted testicular sperm extraction (TESE), have led to men with Klinefelter's syndrome to produce biological offspring. [5], While no cure is known, a number of treatments may help. Considering the names of all three researchers, it is sometimes also called Klinefelter–Reifenstein–Albright syndrome. The affected male has Klinefelter syndrome, a genetic condition that results when a child is born with XXY chromosomes. [42] During puberty and adulthood, low testosterone levels with increased levels of the pituitary hormones FSH and LH in the blood can indicate the presence of Klinefelter syndrome. [17] See also Triple X syndrome. Klinefelter syndrome is a sex chromosome disorder in boys and men that results from the presence of an extra X chromosome in cells. Author information: (1)Division of Genetics, Children's Hospital, Boston, MA 02115. In mammals with more than one X chromosome, the genes on all but one X chromosome are not expressed; this is known as X inactivation. ( Log Out /  [37] These variations are extremely rare. An estimated 50% of Klinefelter’s cases are a result of maternal meiotic errors. An egg with 22 chromosomes that is fertilized by a normal sperm will result in . : Fill in all possibilities of the nondisjunction events for a particular syndrome could originate. -The latter results in Turner syndrome when fertilized by … One of the eggs from such a meiosis could receive both X chromosomes, and the other would receive no X chromosomes. 21 16 22 IXI 12 18 1 15 c) Nondisjunction in meiosis Il Nondisjunction . -The former results in Klinefelter syndrome when fertilized by a Y containing sperm. Klinefelter syndrome (KS) is a condition that occurs in males when they have an extra X chromosome. 2012 by American Society for Reproductive Medicine.) As a result, following meiosis II, two gametes will contain 2 n +1 chromosomes, and the other two gametes will contain n chromosomes. A maternally derived XXY pattern can be traced to an error that occurs during meiosis I, meiosis II, or early mitotic division stages. Accordingly, nondisjunction mutation and translocation mutation are two major types of mutations that occur during cell division. Some males with KS have no obvious signs or symptoms while others may have varying degrees of cognitive, social, behavioral, and learning difficulties. The reason maternal non-disjunction during meiosis II can produce XXY offspring. The relevant nondisjunction in meiosis I occurs when homologous chromosomes, in this case the X and Y or two X sex chromosomes, fail to separate, producing a sperm with an X and a Y chromosome or an egg with two X chromosomes. ... (Turner syndrome), female with three X chromosomes (Trisomy X), male with XXY (Klinefelter syndrome), or male with XYY (XYY syndrome). The origin of the XXY genotype is most commonly from errors related to nondisjunction in paternal meiosis 1 [3]. If gynecomastia is present, the surgical removal of the breast may be considered for both the psychological reasons and to reduce the risk of breast cancer. Thank you! How might this mosaicism come about? [14] Plunkett and Barr found the sex chromatin body in cell nuclei of the body. Possible to have subnormal intelligence [25][26], XXY males are more likely than other men to have certain health problems, such as autoimmune disorders, breast cancer, venous thromboembolic disease, and osteoporosis. Is there any quick, shorthand way to memorize the effects so as to save time on test day? Often there is an azoospermia present, rarely an oligospermia. Question: Nondisjunction M M 31 Exercise 5.2 Errors In Meiosis Can Cause Syndromes Errors In Meiosis Lead To Chromosomal Disorders The Process That Creates Gametes In Human Reproductive Organs Is Called Melosis. A mosaic such as (46, XY/47, XXY) may result from nondisjunction occurring during mitosis, especially at a very early stage of development. The trisomy pattern of Klinefelter’s can occur through various errors. 0%. Once these gametes are fertilized, aneuploidy individuals may result in several syndromes such as Down’s syndrome, Klinefelter syndrome, Turner’s syndrome, etc. All monosomies of autosomal (non-sex) chromosomes are lethal. Learn how to solve nondisjunction problems: predict what nondisjunction events must have occurred in meiosis 1 or 2 in order for a child to be born with a certain condition. [7] Physical therapy, speech and language therapy, counselling, and adjustments of teaching methods may be useful. If a non-disjunction occurs at this point, haploid cells will not be formed. On a microscopic scale this means that the egg or sperm contain an extra X chromosome. Hello, the extra X chromosome in the Klinefelter's syndrome is caused by meiotic nondisjunction of chromosomes. The diagram below shows the proper disjunction and nondisjunction in anaphase. Trisomy – embryo having an extra chromosome Monosomy – embryo missing a chromosomes Genetic Disorder Prominent characteristic of the individual Causes a. Ini terjadi karena kegagalan kromosom homolog untuk memisahkan selama anafase I atau kegagalan kromatid saudara untuk memisahkan selama anafase II di meiosis. Pathophysiology 2) Wikipedia. Create a free website or blog at WordPress.com. [50], This syndrome, evenly distributed in all ethnic groups, has a prevalence of one to two subjects per every 1000 males in the general population. The most common is maternal in nature, resulting in the 47, XXY karyotype. [19] Gynecomastia is present in about a third of affected individuals, a slightly higher percentage than in the XY population. People typically have 46 chromosomes in each cell, two of which are the sex chromosomes. An approach by occupational therapy is useful in children, especially those who have dyspraxia. When in the situation of Klinefelter's or Turner's, the incorrect separation of chromosomes happens during meiosis and happens to the sex determining chromosomes. [41] To investigate the presence of a possible mosaicism, analysis of the karyotype using cells from the oral mucosa is performed. Change ), You are commenting using your Twitter account. In addition to this linkage, roughly 10% of Klinefelter’s individuals exhibit mosaicism, which means that not all cells present with a trisomy pattern and instead, show a normal XY. Patients with klinefelters have an extra x chromosome and are thus XXY males. Which of the following human syndromes is a monosomy? [1] Symptoms are typically more severe if three or more X chromosomes are present (48,XXXY syndrome or 49,XXXXY syndrome). [40], The standard diagnostic method is the analysis of the chromosomes' karyotype on lymphocytes. 9.3.1 Down Syndrome; 9.3.2 XYY and XXX; 9.3.3 Turner Syndrome ; 9.3.4 Klinefelter Syndrome; 9.3.5 Cri-du-Chat Syndrome; 9.3.6 Inversion(9) Contributors and Attributions; The problems described above can affect all eukaryotes, unicellular and multicellular. Karyotyping – The set of chromosomes in a person with Klinefelter syndrome (Doctor Tipser) The extra chromosome is retained because of a nondisjunction event during paternal or maternal meiosis I (gametogenesis). Approximately 15-20% of KS men are defined as ‘mosaics’, usually with two cell lines: 47,XXY / 46,XY [4]. An individual with the appropriate number of chromosomes for their species is called euploid; in humans, euploidy corresponds to 22 pairs of autosomes and one pair of sex chromosomes. Robert S. Sparkes, Barbara F. Crandall, in Fetal-Placental Disorders, 1972. ", "What are the treatments for symptoms in Klinefelter syndrome (KS)? Maternal meiosis II nondisjunction in a case of 47,XXY testicular feminization. Also, there are studies that show that both paternal and maternal age equally contributed to aneuploidy. They may have less muscle control and coordination than other boys of their age. Monosomic human zygotes missing any one copy of an autosome invariably fail to develop to birth because they lack essential genes. The syndrome is also the main cause of male hypogonadism. Occasionally, Errors Occur During Meiosis Result In The Wrong Number Of Chromosomes Ending Up In The Gamete. In adults, possible characteristics vary widely and include little to no sign of affectedness, a lanky, youthful build and facial appearance, or a rounded body type with some degree of gynecomastia (increased breast tissue). ", "How do health care providers diagnose Klinefelter syndrome (KS)? [23] Despite this misunderstanding of the term, however, XXY men may also have microorchidism (i.e., small testicles). [29] Also, delays in motor development may occur, which can be addressed through occupational and physical therapies. [32][51][52][53] However, it is estimated that only 25% of the individuals with Klinefelter syndrome are diagnosed throughout their lives. Occasionally, errors occur during meiosis result in the wrong number of chromosomes ending up in the gamete. Genetic Disorder Nondisjunction of chromosomes – process where chromosomes or chromatids fail to separate during meiosis. ", "Is there a cure for Klinefelter syndrome (KS)? Jacobs described her discovery of this first reported human or mammalian chromosome aneuploidy in her 1981 William Allan Memorial Award address. In 1959, these men with Klinefelter syndrome were discovered to have an extra X chromosome (genotype XXY) instead of the usual male sex complement (genotype XY). [17], During puberty, the physical traits of the syndrome become more evident; because these boys do not produce as much testosterone as other boys, they have a less muscular body, less facial and body hair, and broader hips. [58], "What are common symptoms of Klinefelter syndrome (KS)? Tap card to see definition . Thus, the main difference between nondisjunction in meiosis 1 and 2 is nondisjunction in meiosis 1 occurs in homologous chromosomes while nondisjunction in meiosis II occurs in sister chromatids. a zygote with monosomy. [4][10] The extra X chromosome comes from the father and mother nearly equally. Thus far, only about 10 cases of 47,XXY/46,XX have been described in literature. In humans, the only survivable monosomy is Turner syndrome, which results in an individual who is monosomic for the X chromosome. This is what commonly accompanies nondisjunction. 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