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48,XYYY
XYYY syndrome, also known as 48,XYYY, is a chromosomal disorder in which a male has two extra copies of the Y chromosome. The syndrome is exceptionally rare, with only twelve recorded cases. The presentation of the syndrome is heterogeneous, but appears to be more severe than its counterpart XYY syndrome. Common traits include borderline to mild intellectual disability, infertility, radioulnar synostosis (the fusion of the long bones in the forearm), and in some cases tall stature. Presentation The presentation of XYYY syndrome is variable and at this time not entirely clear. As all known cases were diagnosed postnatally (after birth), and the similar XYY syndrome is known to have a milder phenotype in prenatally than postnatally diagnosed cases, it is suspected that many cases of XYYY syndrome may be mild or asymptomatic. The intellectual abilities of known XYYY cases have varied, especially in cases with mosaicism, but in most cases are in the borderline intellectual function ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aneuploidy
Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a ''euploid'' cell. An extra or missing chromosome is a common cause of some genetic disorders. Some cancer cells also have abnormal numbers of chromosomes. About 68% of human solid tumors are aneuploid. Aneuploidy originates during cell division when the chromosomes do not separate properly between the two cells (nondisjunction). Most cases of aneuploidy in the autosomes result in miscarriage, and the most common extra autosomal chromosomes among live births are 21, 18 and 13. Chromosome abnormalities are detected in 1 of 160 live human births. Autosomal aneuploidy is more dangerous than sex chromosome aneuploidy, as autosomal aneuploidy is almost always lethal to embryos that cease develo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aneuploidies
Aneuploidy is the presence of an abnormal number of chromosomes in a cell (biology), cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more ploidy#Haploid and monoploid, complete sets of chromosomes. A cell with any number of complete chromosome sets is called a ''ploidy#Euploid, euploid'' cell. An extra or missing chromosome is a common cause of some genetic disorders. Some cancer cells also have abnormal numbers of chromosomes. About 68% of human solid tumors are aneuploid. Aneuploidy originates during cell division when the chromosomes do not separate properly between the two cells (nondisjunction). Most cases of aneuploidy in the autosomes result in miscarriage, and the most common extra autosomal chromosomes among live births are Down syndrome, 21, Edwards syndrome, 18 and Patau syndrome, 13. Chromosome abnormality, Chromosome abnormalities are detected in 1 of 160 live human births. Autosomal aneuplo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-disjunction
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division (mitosis/meiosis). There are three forms of nondisjunction: failure of a pair of homologous chromosomes to separate in meiosis I, failure of sister chromatids to separate during meiosis II, and failure of sister chromatids to separate during mitosis. Nondisjunction results in daughter cells with abnormal chromosome numbers (aneuploidy). Calvin Bridges and Thomas Hunt Morgan are credited with discovering nondisjunction in ''Drosophila melanogaster'' sex chromosomes in the spring of 1910, while working in the Zoological Laboratory of Columbia University. Types In general, nondisjunction can occur in any form of cell division that involves ordered distribution of chromosomal material. Higher animals have three distinct forms of such cell divisions: Meiosis I and meiosis II are specialized forms of cell division occurring during generation of gametes (eggs and sperm) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentasomy X
Pentasomy X, also known as 49,XXXXX, is a chromosomal disorder in which a female has five, rather than two, copies of the X chromosome. Pentasomy X is associated with short stature, intellectual disability, characteristic facial features, heart defects, skeletal anomalies, and pubertal and reproductive abnormalities. The condition is exceptionally rare, with an estimated prevalence between 1 in 85,000 and 1 in 250,000. The condition has a large variety of symptoms, and it is difficult to paint a conclusive portrait of its phenotypes. Though significant disability is characteristic, there are so few diagnosed cases that confident conclusions about the presentation and prognosis remain impossible. Pentasomy X may be mistaken for more common chromosomal disorders, such as Down syndrome or Turner syndrome, before a conclusive diagnosis is reached. Pentasomy X is not inherited, but rather occurs via nondisjunction, a random event in gamete development. In rare cases, it may be relat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrasomy X
Tetrasomy X, also known as 48,XXXX, is a chromosomal disorder in which a female has four, rather than two, copies of the X chromosome. It is associated with intellectual disability of varying severity, characteristic "coarse" facial features, heart defects, and skeletal anomalies such as increased height, clinodactyly (incurved pinky fingers), and radioulnar synostosis (fusion of the long bones in the forearm). Tetrasomy X is a rare condition, with few medically recognized cases; it is estimated to occur in approximately 1 in 50,000 females. The disorder has a wide range of symptoms, with phenotypes (presentations) ranging from slight to severe. It is suspected to be underdiagnosed, as are other sex chromosome disorders. Life outcomes vary; some women have had education, employment, and children, while others have remained dependent into adulthood. Life expectancy does not appear to be substantially reduced. Tetrasomy X has phenotypic overlap with a number of more common disord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
XXXY Syndrome
XXXY syndrome is a genetic condition characterized by a sex chromosome aneuploidy, where individuals have two extra X chromosomes. People in most cases have two sex chromosomes: an X and a Y or two X chromosomes. 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. XXXY syndrome is therefore often referred to as 48,XXXY. There is a wide variety of symptoms associated with this syndrome, including cognitive and behavioral problems, taurodontism, and infertility. This syndrome is usually inherited via a new mutation in one of the parents' gametes, as those affected by it are usually infertile. It is estimated that XXXY affects one in every 50,000 male births. Signs and symptoms The symptoms of 48,XXXY syndrome are similar to those of Klinefelter s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosome
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome, allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA. For example, humans have a diploid human genome, genome that usually contains 22 pairs of autosomes and one allosome pair (46 chromosomes total). The autosome pairs are labeled with numbers (1–22 in humans) roughly in order of their sizes in base pairs, while allosomes are labelled with their letters. By contrast, the allosome pair consists of two X chromosomes in females or one X and one Y chromosome in males. Unusual combinations of XYY syndrome, XYY, Klinefelter syndrome, XXY, Triple X syndrome, XXX, XXXX syndrome, XXXX, XXXXX syndrome, XXXXX or XXYY syndrome, XXYY, among Aneuploidy, other Salome combinations, are known to occur and usually cause developmental abnormalities. Autosomes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
At-risk Students
An at-risk student is a term used in the United States to describe a student who requires temporary or ongoing intervention in order to succeed academically. Richardson, Val, comp. "At-Risk Student Intervention Implementation Guide." The Education and Economic Development Coordinating Council At Risk Student Committee (2008) At risk students, sometimes referred to as at-risk youth or at-promise youth, are also adolescents who are less likely to transition successfully into adulthood and achieve economic self-sufficiency.Koball, Heather, et al. (2011). Synthesis of Research and Resources to Support At- Risk Youth, OPRE Report # OPRE 2011–22, Washington, DC: Office of Planning, Research and Evaluation, Administration for Children and Families, U.S. Department of Health and Human Services. Characteristics of at-risk students include emotional or behavioral problems, truancy, low academic performance, showing a lack of interest for academics, and expressing a disconnection from the sc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Education Resources Information Center
The Education Resources Information Center (ERIC) is an online digital library of education research and information. ERIC is sponsored by the Institute of Education Sciences of the United States Department of Education. Description The mission of ERIC is to provide a comprehensive, easy-to-use, searchable, Internet-based bibliographic and full-text database of education research and information for educators, researchers, and the general public. Education research and information are essential to improving teaching, learning, and educational decision-making. ERIC provides access to 1.5 million bibliographic records ( citations, abstracts, and other pertinent data) of journal articles and other education-related materials, with hundreds of new records added every week. A key component of ERIC is its collection of grey literature in education, which is largely available in full text in Adobe PDF format. Approximately one quarter of the complete ERIC Collection is available in fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gender Dysphoria
Gender dysphoria (GD) is the distress a person experiences due to a mismatch between their gender identitytheir personal sense of their own genderand their sex assigned at birth. The diagnostic label gender identity disorder (GID) was used until 2013 with the release of the diagnostic manual DSM-5. The condition was renamed to remove the stigma associated with the term ''disorder''. People with gender dysphoria commonly identify as transgender. Gender nonconformity is not the same thing as gender dysphoria and does not always lead to dysphoria or distress. The causes of gender incongruence are unknown but a gender identity likely reflects genetic, biological, environmental, and cultural factors. Treatment for gender dysphoria may include supporting the individual's gender expression or their desire for hormone therapy or surgery. Treatment may also include counseling or psychotherapy. Some researchers and transgender people support declassification of the condition because t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatogenesis
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. The mitotic division of these produces two types of cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes. The primary spermatocyte divides meiotically (Meiosis I) into two secondary spermatocytes; each secondary spermatocyte divides into two equal haploid spermatids by Meiosis II. The spermatids are transformed into spermatozoa (sperm) by the process of spermiogenesis. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa and four haploid cells. Spermatozoa are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azoospermia
Azoospermia is the medical condition of a man whose semen contains no sperm. It is associated with male infertility, but many forms are amenable to medical treatment. In humans, azoospermia affects about 1% of the male population and may be seen in up to 20% of male infertility situations in Canada. In a non-pathological context, azoospermia is also the intended result of a successful vasectomy. Classification Azoospermia can be classified into three major types as listed. Many conditions listed may also cause various degrees of oligospermia rather than azoospermia. Pretesticular and testicular azoospermia are known as non-obstructive azoospermia, whereas post-testicular azoospermia is considered obstructive. Pretesticular Pretesticular azoospermia is characterized by inadequate stimulation of otherwise normal testicles and genital tract. Typically, follicle-stimulating hormone (FSH) levels are low (hypogonadotropic) commensurate with inadequate stimulation of the testes to prod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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