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Polysomic Inheritance
Polysomy is a condition found in many species, including fungi, plants, insects, and mammals, in which an organism has at least one more chromosome than normal, i.e., there may be three or more copies of the chromosome rather than the expected two copies. Most eukaryotic species are diploid, meaning they have two sets of chromosomes, whereas prokaryotes are haploid, containing a single chromosome in each cell. Aneuploids possess chromosome numbers that are not exact multiples of the haploid number and polysomy is a type of aneuploidy. A karyotype is the set of chromosomes in an organism and the suffix -''somy'' is used to name aneuploid karyotypes. This is not to be confused with the suffix -''ploidy'', referring to the number of complete sets of chromosomes. Polysomy is usually caused by non-disjunction (the failure of a pair of homologous chromosomes to separate) during meiosis, but may also be due to a translocation mutation (a chromosome abnormality caused by rearrangement o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Karyotype With Bands And Sub-bands
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedality, bipedalism and exceptional cognitive skills due to a large and complex Human brain, brain. This has enabled the development of advanced tools, culture, and language. Humans are highly social and tend to live in complex social structures composed of many cooperating and competing groups, from family, families and kinship networks to political state (polity), states. Social interactions between humans have established a wide variety of values, norm (sociology), social norms, and rituals, which bolster human society. Its intelligence and its desire to understand and influence the environment and to explain and manipulate Phenomenon, phenomena have motivated humanity's development of science, philosophy, mythology, religion, and other fields of study. Although some scientists equate the term ''humans'' with all members of the genus ''Homo'', in common usage, it generall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chiasma (genetics)
In genetics, a chiasma (pl. chiasmata) is the point of contact, the physical link, between two (non-sister) chromatids belonging to homologous chromosomes. At a given chiasma, an exchange of genetic material can occur between both chromatids, what is called a chromosomal crossover, but this is much more frequent during meiosis than mitosis. In meiosis, absence of a chiasma generally results in improper chromosomal segregation and aneuploidy. Points of crossing over become visible as chiasma after the synaptonemal complex dissembles and the homologous chromosomes slightly apart from each other. The phenomenon of genetic chiasmata (''chiasmatypie'') was discovered and described in 1909 by Frans Alfons Janssens, a Professor at the University of Leuven in Belgium. When each tetrad, which is composed of two pairs of sister chromatids, begins to split, the only points of contact are at the chiasmata. The chiasmata become visible during the diplotene stage of prophase I of meiosis, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sturgeon
Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ..., and are descended from other, earlier Acipenseriformes, acipenseriform fish, which date back to the Early Jurassic period, some 174 to 201 million years ago. They are one of two living families of the Acipenseriformes alongside paddlefish (Polyodontidae). The family is grouped into four genera: ''Acipenser'' (which is paraphyletic, containing many distantly related sturgeon species), ''Huso'', ''Scaphirhynchus,'' and ''Pseudoscaphirhynchus''. Two species (''Adriatic sturgeon, A. naccarii'' and ''Dabry's sturgeon, A. dabryanus'') may be extinct in the wild, and one (''Syr Darya s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukemia
Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ''leukemia cells''. Symptoms may include bleeding and bruising, bone pain, fatigue, fever, and an increased risk of infections. These symptoms occur due to a lack of normal blood cells. Diagnosis is typically made by blood tests or bone marrow biopsy. The exact cause of leukemia is unknown. A combination of genetic factors and environmental (non-inherited) factors are believed to play a role. Risk factors include smoking, ionizing radiation, petrochemicals (such as benzene), prior chemotherapy, and Down syndrome. People with a family history of leukemia are also at higher risk. There are four main types of leukemia— acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) and chronic myeloi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mosaic (genetics)
Mosaicism or genetic mosaicism is a condition in multicellular organisms in which a single organism possesses more than one genetic line as the result of genetic mutation. This means that various genetic lines resulted from a single fertilized egg. Genetic mosaics may often be confused with chimerism, in which two or more genotypes arise in one individual similarly to mosaicism. In chimerism, though, the two genotypes arise from the fusion of more than one fertilized zygote in the early stages of embryonic development, rather than from a mutation or chromosome loss. Genetic mosaicism can result from many different mechanisms including chromosome nondisjunction, anaphase lag, and endoreplication. Anaphase lagging is the most common way by which mosaicism arises in the preimplantation embryo. Mosaicism can also result from a mutation in one cell during development, in which case the mutation will be passed on only to its daughter cells (and will be present only in certain adult ce ... [...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 18p
Tetrasomy 18p is a genetic condition that is caused by the presence of an isochromosome composed of two copies of the short arm of chromosome 18 in addition to the two normal copies of the chromosome. It is characterized by multiple medical and developmental concerns. Signs and symptoms Tetrasomy 18p causes a wide range of medical and developmental problems.Sebold C, Roeder E, Zimmerman M, Soileau B, Heard P, Carter E, Schatz M, White WA, Perry B, Reinker K, O'Donnell L, Lancaster J, Li J, Hasi M, Hill A, Pankratz L, Hale DE, Cody JD (2010). Tetrasomy 18p: report of the molecular and clinical findings of 43 individuals. Am J Med Genet 152A(9): 2164-72. Congenital anomalies Cardiac anomalies are the most common congenital malformation in individuals with tetrasomy 18p. However, there is no pathognomatic heart defect associated with the condition. Patent ductus arteriosus is the most common defect. Septal defects (ventricular septal defects and atrial septal defects) are a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrasomy 9p
Tetrasomy 9p (also known tetrasomy 9p syndrome) is a rare chromosomal disorder characterized by the presence of two extra copies of the short arm of chromosome 9 (called the p arm), in addition to the usual two. Symptoms of tetrasomy 9p vary widely among affected individuals but typically include varying degrees of delayed growth, abnormal facial features and intellectual disability. Symptoms of the disorder are comparable to those of trisomy 9p. Symptoms and signs The symptoms and prognosis of tetrasomy 9p are highly variable. The severity of the symptoms is largely determined by the size of the isochromosome, the specific regions of chromosome 9p that are duplicated, as well as the number and type of tissues that are affected in the mosaic form. Most patients exhibit some degree of intellectual disability, abnormal skeletal and muscular development, and abnormal facial structures. Cognitive symptoms range from slight learning disabilities to severe deficits in intellectual fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patau Syndrome
Patau syndrome is a syndrome caused by a chromosome, chromosomal abnormality, in which some or all of the Cell (biology), cells of the body contain Trisomy, extra genetic material from chromosome 13 (human), chromosome 13. The extra genetic material disrupts normal development, causing multiple and complex organ defects. This can occur either because each cell contains a full extra copy of chromosome 13 (a disorder known as trisomy 13 or trisomy D or T13), or because each cell contains an extra partial copy of the chromosome, or because there are two different lines of cells—one healthy with the correct number of chromosomes 13 and one that contains an extra copy of the chromosome—mosaicism, mosaic Patau syndrome. Full trisomy 13 is caused by nondisjunction of chromosomes during meiosis (the mosaic form is caused by nondisjunction during mitosis). Like all nondisjunction conditions (such as Down syndrome and Edwards syndrome), the risk of this syndrome in the offspring incr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edwards Syndrome
Edwards syndrome, also known as trisomy 18, is a genetic disorder caused by the presence of a third copy of all or part of chromosome 18. Many parts of the body are affected. Babies are often born small and have heart defects. Other features include a small head, small jaw, clenched fists with overlapping fingers, and severe intellectual disability. Most cases of Edwards syndrome occur due to problems during the formation of the reproductive cells or during early development. The rate of disease increases with the mother's age. Rarely, cases may be inherited from a person's parents. Occasionally, not all cells have the extra chromosome, known as mosaic trisomy, and symptoms in these cases may be less severe. An ultrasound during pregnancy can increase suspicion for the condition, which can be confirmed by amniocentesis. Treatment is supportive. After having one child with the condition, the risk of having a second is typically around one percent. It is the second-most co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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