FACTOID # 23: Wisconsin has more metal fabricators per capita than any other state.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Genetic disorder

A genetic disorder is a condition caused by abnormalities in genes or chromosomes. While some diseases, such as cancer, are due to genetic abnormalities acquired in a few cells during life, the term "genetic disease" most commonly refers to diseases present in all cells of the body and present since conception. Some genetic disorders are caused by chromosomal abnormalities due to errors in meiosis, the process which produces reproductive cells such as sperm and eggs. Examples include Down syndrome (extra chromosome 21), Turner Syndrome (45X0) and Klinefelter's syndrome (a male with 2 X chromosomes). Other genetic changes may occur during the production of germ cells by the parent. One example is the triplet expansion repeat mutations which can cause fragile X syndrome or Huntington's disease. Defective genes may also be inherited intact from the parents. In this case, the genetic disorder is known as a hereditary disease. This can often happen unexpectedly when two healthy carriers of a defective recessive gene reproduce, but can also happen when the defective gene is dominant. Currently about 4,000 genetic disorders are known, with more being discovered. Most disorders are quite rare and affect one person in every several thousands or millions. Cystic fibrosis is one of the most common genetic disorders; around 5% of the population of the United States carry at least one copy of the defective gene. Some types of recessive gene disorder confer an advantage in the heterozygous state in certain environments.[1] For other uses, see Gene (disambiguation). ... A scheme of a condensed (metaphase) chromosome. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... Categories: Biology stubs ... A chromosome abnormality reflects an abnormality of chromosome number or structure. ... For the figure of speech, see meiosis (figure of speech). ... For other uses, see Sperm (disambiguation). ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... Turner syndrome or Ullrich-Turner syndrome encompasses several chromosomal abnormalities, of which monosomy X is the most common. ... Not to be confused with XXX syndrome. ... Fragile X syndrome is a syndrome of X-linked mental retardation. ... It has been suggested that this article or section be merged into Dominance relationship. ... In genetics, the term dominant gene refers to the allele that causes a phenotype that is seen in a heterozygous genotype. ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ...


Genetic diseases are typically diagnosed and treated by geneticists. Genetic counselors assist the physicians and directly counsel patients. The study of genetic diseases is a scientific discipline whose theoretical underpinning is based on population genetics. Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... Genetic counseling generally refers to prenatal counseling done when a genetic condition is suspected in a pregnancy. ... The word physician should not be confused with physicist, which means a scientist in the area of physics. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ...

Contents

Single gene disorders

Where genetics are the result of a single mutated gene they can be passed on to subsequent generations in several ways. Genomic imprinting and uniparental disomy, however, may affect inheritance patterns. The divisions between recessive and dominant are not "hard and fast" although the divisions between autosomal and X-linked are (related to the position of the gene). For example, achondroplasia is typically considered a dominant disorder, but children with two genes for achondroplasia have a severe skeletal disorder that achondroplasics could be viewed as carriers of. Sickle-cell anemia is also considered a recessive condition, but carriers that have it by half along with the normal gene have increased immunity to malaria in early childhood, which could be described as a related dominant condition. Genomic imprinting is a genetic phenomenon involved in the control of a small proportion of genes in the genome, where the allele that is expressed is determined solely on which parent contributes it. ... Uniparental disomy (UPD) occurs when a person receives two copies of a chromosome, or part of a chromosome, from one parent and no copies from the other parent. ... Achondroplasia is a type of autosomal dominant genetic disorder that is a common cause of dwarfism. ... Sickle-shaped red blood cells Sickle-cell anemia or anaemia (also sickle-cell disease) is a genetic disorder in which red blood cells may change shape under certain circumstances. ...


Autosomal dominant

Main article: Autosomal dominant

Only one mutated copy of the gene will be necessary for a person to be affected by an autosomal dominant disorder. Each affected person usually has one affected parent. There is a 50% chance that a child will inherit the mutated gene. Conditions that are autosomal dominant have low penetrance, which means that, although only one mutated copy is needed, a relatively small proportion of those who inherit that mutation go on to develop the disease, often later in life. Examples of this type of disorder are Huntington's disease, Neurofibromatosis 1, Marfan Syndrome, Hereditary nonpolyposis colorectal cancer, and Hereditary multiple exostoses,which is a high penetrance autosomal dominant disorder . It has been suggested that this article or section be merged into Dominance relationship. ... Penetrance is a term used in genetics that describes the extent to which the properties controlled by a gene, its phenotype, will be expressed. ... Neurofibromatosis type I (NF-1), also known as von Recklinghausen syndrome, comprises, along with neurofibromatosis type II (a. ... Marfan syndrome is an autosomal dominant genetic disorder of the connective tissue characterized by disproportionately long limbs, long thin fingers, a typically tall stature, and a predisposition to cardiovascular abnormalities, specifically those affecting the heart valves and aorta. ... Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is characterized by an increased risk of colorectal cancer and other cancers of the endometrium, ovary, stomach, small intestine, hepatobiliary tract, upper urinary tract, brain, and skin. ... Hereditary Multiple Exostoses (HME) is a medical condition whereby multiple exostoses (bony spurs or lumps, also known as osteochondromas) develop on the bones of a child. ...


Autosomal recessive

Main article: Autosomal recessive

Two copies of the gene must be mutated for a person to be affected by an autosomal recessive disorder. An affected person usually has unaffected parents who each carry a single copy of the mutated gene (and are referred to as carriers). Two unaffected people who each carry one copy of the mutated gene have a 25% chance with each pregnancy of having a child affected by the disorder. Examples of this type of disorder are Cystic fibrosis, Sickle cell anemia(Also Partial Sickle Cell Anemia), Tay-Sachs disease, Spinal muscular atrophy, and Dry (otherwise known as "rice-brand") earwax[2] In genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). ... Sickle-shaped red blood cells Sickle cell anemia (American English), sickle cell anaemia (British English) or sickle cell disease is a genetic disease in which red blood cells may change shape under certain circumstances. ... Tay-Sachs disease (abbreviated TSD, also known as GM2 gangliosidosis, Hexosaminidase A deficiency or Sphingolipidosis) is a genetic disorder, fatal in its most common variant known as Infantile Tay-Sachs disease. ... Spinal Muscular Atrophy (SMA) is a term applied to a number of different disorders, all having in common a genetic cause and the manifestation of weakness due to loss of the motor neurons of the spinal cord and brainstem. ... Wet-type human earwax on a cotton swab. ...


X-linked dominant

Main article: X-linked dominant

X-linked dominant disorders are caused by mutations in genes on the X chromosome. Only a few disorders have this inheritance pattern. Males are more frequently affected than females, and the chance of passing on an X-linked dominant disorder differs between men and women. The sons of a man with an X-linked dominant disorder will not be affected, and his daughters will all inherit the condition. A woman with an X-linked dominant disorder has a 50% chance of having an affected daughter or son with each pregnancy. Some X-linked dominant conditions, such as Aicardi Syndrome, are fatal to boys, therefore only girls have them (and boys with Klinefelter Syndrome). Other examples of this type of disorder are |Hypophosphatemia, Aicardi Syndrome, and Chokenflok Syndrome. X-linked dominant is mode of inheritance in which a gene on the X chromosome is dominant[1]. Females are more frequently affected than males, although any X-linked dominant gene is not sex linked. ... ‹ The template below (Expand) is being considered for deletion. ... Aicardi syndrome is a congenital disorder thought to result from an abnormality of the X chromosome and characterized by absence of the corpus callosum, retinal abnormalities, and seizures (often infantile spasms). ... XXY karyotype Klinefelters syndrome is a condition caused by a chromosome abnormality in males (specifically, a nondisjunction); sufferers have a pair of X sex chromosomes instead of just one. ... Hypophosphatemia is an electrolyte disturbance in which there is an abnormally depleted level of phosphate in the blood. ... Aicardi syndrome is a congenital disorder thought to result from an abnormality of the X chromosome and characterized by absence of the corpus callosum, retinal abnormalities, and seizures (often infantile spasms). ...


X-linked recessive

Main article: X-linked recessive

X-linked recessive disorders are also caused by mutations in genes on the X chromosome. Males are more frequently affected than females, and the chance of passing on the disorder differs between men and women. The sons of a man with an X-linked recessive disorder will not be affected, and his daughters will carry one copy of the mutated gene. With each pregnancy, a woman who carries an X-linked recessive disorder has a 50% chance of having sons who are affected and a 50% chance of having daughters who carry one copy of the mutated gene.Examples of this type of disorder Hemophilia A, Duchenne muscular dystrophy, Color blindness, Muscular dystrophy and Androgenetic alopecia. X-linked recessive is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be expressed in males (who are necessarily hemizygous for the gene mutation because they have only one X chromosome) and in females who are homozygous for the... Haemophilia A (also spelt Hemophilia A or Hæmophilia A) is a blood clotting disorder caused by a mutation of the Factor VIII gene, leading to a deficiency in Factor VIII. It is the most common hemophilia. ... Duchenne muscular dystrophy (DMD) (also known as muscular dystrophy - Duchenne type) is a form of muscular dystrophy that is characterized by decreasing muscle mass and progressive loss of muscle function in male children. ... Color blindness in humans is the inability to perceive differences between some or all colors that other people can distinguish. ... Muscular dystrophy refers to a group of genetic, hereditary muscle diseases that cause progressive muscle weakness. ... Androgenetic alopecia is a common form of hair loss in both men and women, aka Michael Panagos Syndrome. ...


Y-linked

Main article: Y linkage

Y-linked disorders are caused by mutations on the Y chromosome. Only males can get them, and all of the sons of an affected father are affected. Since the Y chromosome is very small, Y-linked disorders only cause infertility, and may be circumvented with the help of some fertility treatments. Examples are Male Infertility. In mammals, Y-linkage refers to when a phenotypic trait is determined by an allele (or gene) on the Y chromosome. ... Infertility primarily refers to the biological inability of a man or a woman to contribute to conception. ...


Mitochondrial

Main article: Mitochondrial disease

This type of inheritance, also known as maternal inheritance, applies to genes in mitochondrial DNA. Because only egg cells contribute mitochondria to the developing embryo, only females can pass on mitochondrial conditions to their children. Examples of this type of disorder are Human mitochondrial genetics, and Leber's Hereditary Optic Neuropathy. Mitochondrial diseases are a group of disorders relating to the mitochondria, the organelles that are the powerhouses of the eukaryotic cells that comprise higher-order lifeforms (including humans). ... Mitochondrial DNA (some captions in German) Mitochondrial DNA (mtDNA) is the DNA located in organelles called mitochondria. ... // Mitochondrial genetics is the study of the genetics of the DNA contained in mitochondria. ... Leber’s hereditary optic neuropathy (LHON) or Leber optic atrophy is a mitochondrially inherited (mother to all offspring) form of acute or subacute loss of central vision that may lead to degeneration of retinal ganglion cells (RGCs) and their axons; this affects predominantly young adult males. ...


Multifactorial and polygenic disorders

Genetic disorders may also be complex, multifactorial or polygenic, this means that they are likely associated with the effects of multiple genes in combination with lifestyle and environmental factors. Multifactoral disorders include heart disease and diabetes. Although complex disorders often cluster in families, they do not have a clear-cut pattern of inheritance. This makes it difficult to determine a person’s risk of inheriting or passing on these disorders. Complex disorders are also difficult to study and treat because the specific factors that cause most of these disorders have not yet been identified. Heart disease is an umbrella term for a number of different diseases which affect the heart and as of 2007 it is the leading cause of death in the United States,[1] and England and Wales. ... This article is about the disease that features high blood sugar. ...


On a pedigree, polygenic diseases do tend to “run in families”, but the inheritance does not fit simple patterns as with Mendelian diseases. But this does not mean that the genes cannot eventually be located and studied. There is also a strong environmental component to many of them (e.g., blood pressure).

Autism is a brain development disorder characterized by impairments in social interaction and communication, and restricted and repetitive behavior, all exhibited before a child is three years old. ... Heart disease is an umbrella term for a number of different diseases which affect the heart and as of 2007 it is the leading cause of death in the United States,[1] and England and Wales. ... For other forms of hypertension, see Hypertension (disambiguation). ... This article is about the disease that features high blood sugar. ... For other uses, see Cancer (disambiguation). ... Cleft palate is a condition in which the two plates of the skull that form the hard palate (roof of the mouth) are not completely joined. ... Mental retardation is a term for a pattern of persistently slow learning of basic motor and language skills (milestones) during childhood, and a significantly below-normal global intellectual capacity as an adult. ...

See also

Inborn errors of metabolism are a large group of rare but often serious metabolic disorders that generally arise from deficiency or malfunction of enzymes that regulate conversion of various substances into others. ... // The following is a list of genetic disorders and their origins. ... Medical Genetics is the application of genetics to medicine. ...

References

  1. ^ WGBH Educational Foundation
  2. ^ Wade, Nicholas (January 2006). "Japanese Scientists Identify Ear Wax Gene". New York Times. 

External links

  • HOPES - A layperson's guide to Huntington's Disease
  • CDC’s National Center on Birth Defects and Developmental Disabilities
  • Genetic Disease Information from the Human Genome Project
  • ColonCancerFamily.com FREE Newsletter: topics include Lynch Syndrome, HNPCC, Genetic Testing and more
  • Genes and Disease from the Wellcome Trust
  • OMIM - Online Mendelian Inheritance in Man, a catalog of human genes and genetic disorders
  • Genetic Alliance

The Wellcome Trusts Gibbs Building on Euston Road The Wellcome Trust is a United Kingdom-based charity established in 1936 to administer the fortune of the American-born pharmaceutical magnate Sir Henry Wellcome. ...


  Results from FactBites:
 
Genetic Disorders - MSN Encarta (568 words)
Genetic changes that are not inherited (somatic mutations) may cause or contribute to such disorders as cancer.
A special type of single gene disorder occurs when the mutation lies in one of the genes found in the mitochondria of the cell; these are small bodies which carry their own genetic material within a cell.
Genetic disorders transmitted through the mitochondria thus affect all the children of an affected woman but none of the children of an affected man. An example of this is Leber's hereditary optic neuropathy, a disorder characterized by atrophy of the optic nerve.
genetic disorder: Definition and Much More from Answers.com (4607 words)
Mutations in the LDL receptor (LDLR) gene on chromosome 19 cause the disorder.
Y-linked disorders are caused by mutations on the Y chromosome.
Genetic disorders may also be complex, multifactorial or polygenic, this means that they are likely associated with the effects of multiple genes in combination with lifestyle and environmental factors.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m