|
Monosomy
Monosomy is a form of aneuploidy with the presence of only one chromosome from a pair. Partial monosomy occurs when a portion of one chromosome in a pair is missing. Human monosomy Human conditions due to monosomy: * Turner syndrome – People with Turner syndrome typically have one X chromosome instead of the usual two X chromosomes. Turner syndrome is the only full monosomy that is seen in humans — all other cases of full monosomy are lethal and the individual will not survive development. * Cri du chat syndrome – (French for "cry of the cat" after the persons' malformed larynx) a partial monosomy caused by a deletion of the end of the short arm of chromosome 5 * 1p36 deletion syndrome – a partial monosomy caused by a deletion at the end of the short arm of chromosome 1 * 17q12 microdeletion syndrome - a partial monosomy caused by a deletion of part of the long arm of chromosome 17 See also * Anaphase lag * Miscarriage Miscarriage, also known in medical terms as a spo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turner Syndrome
Turner syndrome (TS), also known as 45,X, or 45,X0, is a genetic condition in which a female is partially or completely missing an X chromosome. Signs and symptoms vary among those affected. Often, a short and webbed neck, low-set ears, low hairline at the back of the neck, short stature, and swollen hands and feet are seen at birth. Typically, those affected do not develop menstrual periods, or breasts without hormone treatment and are unable to have children without reproductive technology. Heart defects, diabetes, and low thyroid hormone occur in the disorder more frequently than average. Most people with Turner syndrome have normal intelligence; however, many have problems with spatial visualization that may be needed in order to learn mathematics. Vision and hearing problems also occur more often than average. Turner syndrome is not usually inherited; rather, it occurs during formation of the reproductive cells in a parent or in early cell division during development. ... [...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] |
Cri Du Chat
Cri du chat syndrome is a rare genetic disorder due to a partial chromosome deletion on chromosome 5. Its name is a French term ("cat-cry" or " call of the cat") referring to the characteristic cat-like cry of affected children. It was first described by Jérôme Lejeune in 1963. The condition affects an estimated 1 in 50,000 live births across all ethnicities and is more common in females by a 4:3 ratio. Signs and symptoms The syndrome gets its name from the characteristic cry of affected infants, which is similar to that of a meowing kitten, due to problems with the larynx and nervous system. About one third of children lose the cry by age of 2 years. Other symptoms of cri du chat syndrome may include: * feeding problems because of difficulty in swallowing and sucking; * mutism; * low birth weight and poor growth; * severe cognitive, speech and motor disabilities; * behavioural problems such as hyperactivity, aggression, outbursts and repetitive movements; * unusual facial fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 5
Chromosome 5 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 5 spans about 181 million base pairs (the building blocks of DNA) and represents almost 6% of the total DNA in cells. Chromosome 5 is the 5th largest human chromosome, yet has one of the lowest gene densities. This is partially explained by numerous gene-poor regions that display a remarkable degree of non-coding and syntenic conservation with non-mammalian vertebrates, suggesting they are functionally constrained. Because chromosome 5 is responsible for many forms of growth and development (cell divisions) changes may cause cancers. One example would be acute myeloid leukemia (AML). Genes Number of genes The following are some of the gene count estimates of human chromosome 5. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1p36 Deletion Syndrome
1p36 deletion syndrome is a congenital genetic disorder characterized by moderate to severe intellectual disability, delayed growth, hypotonia, seizures, limited speech ability, malformations, hearing and vision impairment, and distinct facial features. The symptoms may vary, depending on the exact location of the chromosomal deletion. The condition is caused by a genetic deletion (loss of a segment of DNA) on the outermost band on the short arm (p) of chromosome 1. It is one of the most common deletion syndromes. It is estimated that the syndrome occurs in one in every 5,000 to 10,000 births. Signs and symptoms There are a number of signs and symptoms characteristic of monosomy 1p36, but no one individual will display all of the possible features. In general, children will exhibit failure to thrive and global delays. Developmental and behavioral Most young children with 1p36 deletion syndrome have delayed development of speech and motor skills. Speech is severely affected, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 1
Chromosome 1 is the designation for the largest human chromosome. Humans have two copies of chromosome 1, as they do with all of the autosomes, which are the non-sex chromosomes. Chromosome 1 spans about 249 million nucleotide base pairs, which are the basic units of information for DNA.http://vega.sanger.ac.uk/Homo_sapiens/mapview?chr=1 Chromosome size and number of genes derived from this database, retrieved 2012-03-11. It represents about 8% of the total DNA in human cells. It was the last completed chromosome, sequenced two decades after the beginning of the Human Genome Project. Genes Number of genes The following are some of the gene count estimates of human chromosome 1. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project ( CCDS) takes an extremely conservative strategy. So ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaphase Lag
Anaphase lag is a consequence of an event during cell division where sister chromatids do not properly separate from each other because of improper spindle formation. The chromosome or chromatid does not properly migrate during anaphase and the daughter cells will lose some genetic information. It is one of many causes of aneuploidy. This event can occur during both meiosis and mitosis with unique repercussions. In either case, anaphase lag will cause one daughter cell to receive a complete set of chromosomes while the other lacks one paired set of chromosomes, creating a form of monosomy. Whether the cell survives depends on which sister chromatid was lost and the background genomic state of the cell. The passage of abnormal numbers of chromosomes will have unique consequences with regards to mosaicism and development as well as the progression and heterogeneity of cancers. Mechanisms There are two notable mechanisms that cause Anaphase Lag, each of which are characterized by mero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miscarriage
Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the death of an embryo or fetus before it is able to survive independently. Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemical loss. Once ultrasound or histological evidence shows that a pregnancy has existed, the used term is clinical miscarriage, which can be ''early'' before 12 weeks and ''late'' between 12-21 weeks. Fetal death after 20 weeks of gestation is also known as a stillbirth. The most common symptom of a miscarriage is vaginal bleeding with or without pain. Sadness, anxiety, and guilt may occur afterwards. Tissue and clot-like material may leave the uterus and pass through and out of the vagina. Recurrent miscarriage (also referred to medically as Recurrent Spontaneous Abortion or RSA) may also be considered a form of infertility. Risk factors for miscarriage include being an older parent, previous miscarriage, exposure to tobacco smoke, obesity, dia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Genetics
Medical genetics is the branch tics in that human genetics is a field of scientific research that may or may not apply to medicine, while medical genetics refers to the application of genetics to medical care. For example, research on the causes and inheritance of genetic disorders would be considered within both human genetics and medical genetics, while the diagnosis, management, and counselling people with genetic disorders would be considered part of medical genetics. In contrast, the study of typically non-medical phenotypes such as the genetics of eye color would be considered part of human genetics, but not necessarily relevant to medical genetics (except in situations such as albinism). ''Genetic medicine'' is a newer term for medical genetics and incorporates areas such as gene therapy, personalized medicine, and the rapidly emerging new medical specialty, predictive medicine. Scope Medical genetics encompasses many different areas, including clinical practice of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). Before this happens, each chromosome is duplicated ( S phase), and both copies are joined by a centromere, resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. The joined copies are now called si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Larynx
The larynx (), commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal inlet is about 4–5 centimeters in diameter. The larynx houses the vocal cords, and manipulates pitch and volume, which is essential for phonation. It is situated just below where the tract of the pharynx splits into the trachea and the esophagus. The word ʻlarynxʼ (plural ʻlaryngesʼ) comes from the Ancient Greek word ''lárunx'' ʻlarynx, gullet, throat.ʼ Structure The triangle-shaped larynx consists largely of cartilages that are attached to one another, and to surrounding structures, by muscles or by fibrous and elastic tissue components. The larynx is lined by a ciliated columnar epithelium except for the vocal folds. The cavity of the larynx extends from its triangle-shaped inlet, to the epiglottis, and to the circular outlet at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
17q12 Microdeletion Syndrome
17q12 microdeletion syndrome, also known as 17q12 deletion syndrome, is a rare chromosomal anomaly caused by the deletion of a small amount of material from a region in the long arm of chromosome 17. It is typified by deletion of the HNF1B gene, resulting in kidney abnormalities and renal cysts and diabetes syndrome. It also has neurocognitive effects, and has been implicated as a genetic factor for autism and schizophrenia. 17q12 microdeletion syndrome is not to be confused with 17q12 microduplication syndrome, caused by the addition of genetic material in the same region from which it is removed in the microdeletion, or 17q21.31 microdeletion syndrome, another name for Koolen–De Vries syndrome. Presentation 17q12 microdeletions have a variable phenotype, ranging from few or no symptoms to severe disability. The condition is thought to be underdiagnosed, and cases with milder phenotypes may not reach clinical attention unless they have an affected child themselves. The m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
