"processing or the ‘social brain'. X chromosome The X chromosome is one of the two sex-determining chromosomes (allosomes) in many organisms, including mammals (the other is the Y chromosome), and is found in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system. The X chromosome was named for its unique properties by early researchers, which resulted in the naming of its counterpart Y chromosome, for the next letter in the alphabet, following its subsequent discovery. It was first noted that the X chromosome was special in 1890 by Hermann Henking in Leipzig."
"as female, as humans have an XY sex-determination system. X0 sex-determination system The X0 sex-determination system is a system that determines the sex of offspring among: In this system, there is only one sex chromosome, referred to as X. Males only have one X chromosome (X0), while females have two (XX). The zero (sometimes, the letter O) signifies the lack of a second X. Maternal gametes always contain an X chromosome, so the sex of the animals’ offspring depends on whether a sex chromosome is present in the male gamete. Its sperm normally contain either one X chromosome or no"
"of one sex or the other. In practice, the term almost always refers to X-linked traits and a great many such traits (such as red-green colour vision deficiency) are not affected by sex. Females have two copies of every gene locus found on the X chromosome, just as for the autosomes, and the same dominance relationships apply. Males however have only one copy of each X chromosome gene locus, and are described as hemizygous for these genes. The Y chromosome is much smaller than the X, and contains a much smaller set of genes, including, but not limited to, those"
"XY sex-determination system The XY sex-determination system is the sex-determination system found in humans, most other mammals, some insects (""Drosophila""), some snakes, and some plants (""Ginkgo""). In this system, the sex of an individual is determined by a pair of sex chromosomes. Females typically have two of the same kind of sex chromosome (XX), and are called the homogametic sex. Males typically have two different kinds of sex chromosomes (XY), and are called the heterogametic sex. Exceptions to this are cases of XX males or XY females, or other syndromes. The XY system contrasts in several ways with the ZW"
"genetically determined as such by the XY sex-determination system where males have an XY (as opposed to XX) sex chromosome. It is also possible in a variety of species, including humans, to be XXY or have other intersex/hermaphroditic qualities, though one would still be considered genotypically (if not necessarily phenotypically) male so long as one has a Y-chromosome. During reproduction, a male can give either an X sperm or a Y sperm, while a female can only give an X egg. A Y sperm and an X egg produce a male, while an X sperm and an X egg produce"
"the sex X chromosome. X-linked genes just like autosomal genes have both dominant and recessive types. Recessive X-linked disorders are rarely seen in females and usually only affect males. This is because males inherit their X chromosome and all X-linked genes will be inherited from the maternal side. Fathers only pass on their Y chromosome to their sons, so no X-linked traits will be inherited from father to son. Men cannot be carriers for recessive X linked traits, as they only have one X chromosome, so any X linked trait inherited from the mother will show up. Females express X-linked"
"X chromosome in each body cell. All diploid organisms with allosome-determined sex get half of their allosomes from each of their parents. In mammals, females are XX, they can pass along either of their X’s, and since the males are XY they can pass along either an X or a Y. For a mammal to be chromosomally female, the individual must receive an X chromosome from both parents, whereas to be chromosomally male, the individual must receive a X chromosome from their mother and a Y chromosome from their father. It is thus the male’s sperm that determines the sex"
"46,XX testicular disorders of sex development 46,XX testicular disorders of sex development (46,XX DSD) describes a condition in which individuals with two X chromosomes in each cell, the pattern typically found in females, have a male phenotype appearance. 46,XX testicular disorders of sex development may also be named 46,XX sex reversal, nonsyndromic 46,XX testicular DSD, XX male syndrome, and XX sex reversal. People with 46,XX testicular DSD have male external genitalia. They generally have small testes and may also have abnormalities such as undescended testes (cryptorchidism) or the urethra opening on the underside of the penis (hypospadias). A small number"
"what point in development these mutations occur. Males typically have one X chromosome and one Y chromosome in each diploid cell of their bodies. Females typically have two X chromosomes. XX males that are SRY-positive have two X chromosomes, with one of them containing genetic material from the Y chromosome, making them phenotypically male but genetically female. The SRY gene plays an important role in sex determination by initiating testicular development. In most XX males the SRY gene is present. The tip of the Y chromosome contains the SRY gene and, during recombination, a translocation occurs in which the SRY"
"pair consists of two X chromosomes in females or one X and one Y chromosome in males. Unusual combinations of XYY, XXY, XXX, XXXX, XXXXX or XXYY, among other allosome combinations, are known to occur and usually cause developmental abnormalities. Autosomes still contain sexual determination genes even though they are not sex chromosomes. For example, the SRY gene on the Y chromosome encodes the transcription factor TDF and is vital for male sex determination during development. TDF functions by activating the SOX9 gene on chromosome 17, so mutations of the SOX9 gene can cause humans with an ordinary Y chromosome"
"the male sex determination, which was named SRY (sex-determining region of the Y chromosome). XY sex-determination system The XY sex-determination system is the sex-determination system found in humans, most other mammals, some insects (""Drosophila""), some snakes, and some plants (""Ginkgo""). In this system, the sex of an individual is determined by a pair of sex chromosomes. Females typically have two of the same kind of sex chromosome (XX), and are called the homogametic sex. Males typically have two different kinds of sex chromosomes (XY), and are called the heterogametic sex. Exceptions to this are cases of XX males or XY"
"As the syndrome is due to a chromosomal non-disjunction event, the recurrence risk is not high compared to the general population. There has been no evidence found that indicates non-disjunction occurs more often in a particular family. Category Syndromes Category Syndromes XXXY syndrome XXXY syndrome is a genetic disorder characterized by a sex chromosome aneuploidy, where males have two extra X chromosomes. Males typically have only two sex chromosomes, an X and a Y. The presence of one Y chromosome with a functioning SRY gene causes the expression of genes that determine maleness. Because of this, XXXY syndrome only affects"
"the karyotype 46,XX, but around one in a thousand will be 47,XXX, and one in 2500 will be 45,X. This contrasts with the typical male karotype of 46,XY; thus, the X and Y chromosomes are known as female and male, respectively. Because humans inherit mitochondrial DNA only from the mother's ovum, genetic studies of the female line tend to focus on mitochondrial DNA. Whether or not a child is considered female does not always determine whether or not the child later will identify themselves that way (see gender identity). For instance, intersex individuals, who have mixed physical and/or genetic features,"
"rare Haemophilia B. The sex-linked X chromosome disorder manifests almost exclusively in males, even though the genetic mutation causing the disorder is located on the X chromosome and can be inherited from the mother by male children or from either mother or father by female children. This is because the trait is recessive, meaning that only one correctly-functioning copy of the blood clotting factor gene is necessary for normal clotting. Females have two X chromosomes, and hence redundant copies of the blood clotting factor gene located on them. A female who inherits a mutated copy on one X chromosome has"
"humans, generally men are affected and women are carriers for two reasons. The first is the simple statistical fact that if the X-chromosomes in a population that carry a particular X-linked mutation at a frequency of 'f' (for example, 1%) then that will be the frequency that men are likely to express the mutation (since they have only one X), while women will express it at a frequency of f (for example 1% * 1% = 0.01%) since they have two X's and hence two chances to get the normal allele. Thus, X-linked mutations tend to be rare in women."
"of females, are red-green color blind in some way or another, whether it is one color, a color combination, or another mutation. Males are at a greater risk of inheriting an X-linked mutation because males only have one X chromosome (XY, with the Y chromosome carrying altogether different genes from the X chromosome), and females have two (XX); if a woman inherits a normal X chromosome in addition to the one that carries the mutation, she will not display the mutation. Men do not have a second X chromosome to override the chromosome that carries the mutation. If 8% of"
"This occurs when one X chromosome contains a segment of the Y chromosome, which was inserted into the X chromosome of the father's sperm. Rarely females are born with the XY genotype. They are found to be missing the same portion of the Y chromosome it was inserted into the chromosome of XX males. The gene for sexual differentiation in humans, called the testis determining factor (TDF), is located on the short arm of the Y chromosome. The presence or absence of the Y chromosome determines whether the embryo will have testes or ovaries. An abnormal number of sex chromosomes"
"triggering male development. The ""default sex,"" in the absence of a Y chromosome, is female-like. This is because of the presence of the sex-determining region of the Y chromosome, also known as the SRY gene. Thus, male mammals typically have an X and a Y chromosome (XY), while female mammals typically have two X chromosomes (XX). In humans, biological sex is determined by five factors present at birth: the presence or absence of a Y chromosome, the type of gonads, the sex hormones, the internal genitalia (such as the uterus in females), and the external genitalia. Chromosomal sex is determined"
"also inherited a second X chromosome from the other parent that is likely to carry a non-mutated copy of the gene, capable of directing appropriate clotting. Such a female, with normal clotting but possessing a single mutated copy of the gene, is called a carrier. Males only possess a single X chromosome, inherited from their mother, having received a Y chromosome from their father instead of a second X. If their sole X chromosome contains the haemophilia mutation they possess no second copy to provide for normal function, as in carrier females. Each child of a carrier will have a"
"XXXY syndrome XXXY syndrome is a genetic disorder characterized by a sex chromosome aneuploidy, where males have two extra X chromosomes. Males typically have only two sex chromosomes, an X and a Y. The presence of one Y chromosome with a functioning SRY gene causes the expression of genes that determine maleness. Because of this, XXXY syndrome only affects males. The additional two X chromosomes in males with XXXY syndrome causes them to have 48 chromosomes, instead of the typical 46. So, XXXY syndrome is often referred to as 48, XXXY. There are a wide variety of symptoms associated with"
"the X linked sex gene. Since this syndrome is X linked, the chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. Carrier females usually do not display symptoms of the disorder because it is usually the X chromosome with the abnormal gene that is “turned off”. Parents can undergo genetic testing to see if their child will get this syndrome,"
"as is the case with German infants who may not be assigned to male or female categories. Sociological research in Australia, a country with a third 'X' sex classification, shows that 19% of people born with atypical sex characteristics selected an ""X"" or ""other"" option, while 52% are women, 23% men, and 6% unsure. Alex MacFarlane is believed to be the first person in Australia to obtain a birth certificate recording sex as indeterminate, and the first Australian passport with an 'X' sex marker in 2003. On September 26, 2016, California resident Sara Kelly Keenan became the second person in"
"duplicates of either of the sets of chromosomes carried in the diploid chromosomes, and often undergo random mutations resulting in modified DNA (and subsequently, new proteins and phenotypes). In humans, a normal ovum can carry only an X chromosome (of the X and Y chromosomes), whereas a sperm may carry either an X or a Y (a non-normal ovum can end up carrying two or no X chromosomes, as a result of an irregularity at either of the two stages of meiosis, while a non-normal sperm cell can end up carrying either no sex-defining chromosomes, an XY pair, or XX"
"in a different phenotype, is ""not"" a change at the genotypic level. For an individual cell or lineage the inactivation is therefore skewed or 'non-random', and this can give rise to mild symptoms in female 'carriers' of X-linked genetic disorders. Normal females possess two X chromosomes, and in any given cell one chromosome will be active (designated as Xa) and one will be inactive (Xi). However, studies of individuals with extra copies of the X chromosome show that in cells with more than two X chromosomes there is still only one Xa, and all the remaining X chromosomes are inactivated."
"This indicates that the default state of the X chromosome in females is inactivation, but one X chromosome is always selected to remain active. It is understood that X-chromosome inactivation is a random process, occurring at about the time of gastrulation in the epiblast (cells that will give rise to the embryo). The maternal and paternal X chromosomes have an equal probability of inactivation. This would suggest that women would be expected to suffer from X-linked disorders approximately 50% as often as men (because women have two X chromosomes, while men have only one); however, in actuality, the occurrence of"
"chromosome, thus would become a carrier. Genetic females (46,XX karyotype) have two X chromosomes, thus have two ""AR"" genes. A mutation in one (but not both) results in a minimally affected, fertile, female carrier. Some carriers have been noted to have slightly reduced body hair, delayed puberty, and/or tall stature, presumably due to skewed X-inactivation. A female carrier will pass the affected ""AR"" gene to her children 50% of the time. If the affected child is a genetic female, she, too, will be a carrier. An affected 46,XY child will have AIS. A genetic female with mutations in both ""AR"""
"to have implications for understanding the transfer of epigenetic activity along long genomic stretches. Other species that do not follow the previously discussed conventions of XX females and XY males must find alternative ways to equalize X-linked gene expression among differing sexes. For example, in ""Caenorhabditis elegans"" (or ""C. elegans""), sex is determined by the ratio of X chromosomes relative to autosomes; worms with two X chromosomes (XX worms) develop as hermaphrodites, whereas those with only one X chromosome (XO worms) develop as males. This system of sex determination is unique, because there is no male specific chromosome, as is"
"sex only has one set of X chromosome genes. The inactive X chromosome in cells of females is visible as a Barr body under the microscope. Males do not have Barr bodies as they only have one X chromosome. Xist is only expressed from the future inactive X chromosome in females and is able to ""coat"" the chromosome from which it was produced. Many copies of Xist RNA bind the future inactivated X chromosome. Tsix prevents the accumulation of Xist on the future active female X chromosome to maintain the active euchromatin state of the chosen chromosome. In the extra-embryonic"
"as an X0 sex-determination system. In haplodiploidy, males receive one half of the chromosomes that females receive, including autosomes. In an X0 sex-determination system, males and females receive an equal number of autosomes, but when it comes to sex chromosomes, females will receive two X chromosomes while males will receive only a single X chromosome. Several models have been proposed for the genetic mechanisms of haplodiploid sex-determination. The model most commonly referred to is the ""complementary allele model"". According to this model, if an individual is heterozygous for a certain locus, it develops into a female, whereas hemizygous and homozygous"
"on the X chromosome. Genetic females (XX) will show symptoms of the disease only if both their X chromosomes are defective with a similar deficiency, whereas genetic males (XY) will show symptoms of the disease if their only X chromosome is defective. (A woman may carry such a disease on one X chromosome but not show symptoms if the other X chromosome works sufficiently.) For this reason, such conditions are far more common in males than in females. X-linked recessive disorders include: X-linked dominant disorders include: There are diseases that are caused by a defective Y chromosome or of a"
"at the time of fertilization by the genetic material carried in the sperm cell. If a sperm cell carrying an X chromosome fertilizes the egg, the offspring will typically be female (XX); if a sperm cell carrying a Y chromosome fertilizes the egg, the offspring will typically be male (XY). Persons whose anatomy or chromosomal makeup differ from this pattern are referred to as intersex. This is referred to as the XY sex-determination system and is typical of most mammals, but quite a few other sex-determination systems exist, including some that are non-genetic. The term ""primary sexual characteristics"" denotes the"
"distributed among 2 homologous groups of 23 heterologous chromosomes each, while the base pairs of the XY male zygote are distributed among 2 homologous groups of 22 heterologous chromosomes each plus 2 heterologous chromosomes. Although each zygote has 46 chromosomes, 23 chromosomes of the XX female zygote are heterologous while 24 chromosomes of the XY male zygote are heterologous. As a result, the C-value for the XX female zygote is 3.099361 while the C-value for the XY male zygote is 3.157877. The human genome's GC content is about 41%. Accounting for the autosomal, X, and Y chromosomes, human haploid GC"
"two of each chromosome and thus two copies of every gene. The two alleles for a gene are located on identical loci of the two homologous chromosomes, each allele inherited from a different parent. Many species have so-called sex chromosomes that determine the gender of each organism. In humans and many other animals, the Y chromosome contains the gene that triggers the development of the specifically male characteristics. In evolution, this chromosome has lost most of its content and also most of its genes, while the X chromosome is similar to the other chromosomes and contains many genes. The X"