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What Type Of Mutation Causes Down Syndrome
In genetics, a mutation is a change in the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element. Mutations result from unrepaired damage to dna or to RNA genomes (typically caused by radiation or chemical mutagens), from errors in the process of replication, or from the insertion or deletion of segments of dna ...Read more
Not mutation,number : Down syndrome is an abnormality of chromosome numbers, not a trait or mutation in the gene code. During conception only one of chromosome of each pair is given by both parents to the fertile egg.If a parent adds their 2 nbr 21chm to the other parents nbr 21, 3 end up in the egg ; the excess 21 causes the all the problems.Rare forms are causes by a extra piece of a 21, but that's another issue. ...Read moreSee 1 more doctor answer
X-linked mutation: Barth syndrome, also known as 3-methylglutaconic aciduria type II (MGCA2), is caused by mutation in the tafazzin gene (TAZ) on chromosome Xq28. Each boy born to a carrier mother has a 50% chance of having it. Each daughter of a carrier mother has a 50% chance of being a carrier. All daughters of men with Barth Syndrome are carriers. https://www.barthsyndrome.org/home has information & resources. ...Read more
Autosomal dominant: Alagille syndrome has an autsomal dominant genetic inheritance pattern. It is rare, however, and affects the heart and liver primarily. In 90% of cases, mutations on chromosome 20 that affect the JAG1 gene causes this syndrome. A few people have mutations in a gene called NOTCH2. Defects in these genes are thought to lead to abnormal embryonic development in the affected organs. ...Read more
Extra chromosome mtl: The traditional ds patient has an extra 21 chromosome(c) that resulted from an improper splitting of the c pairs as the egg is being formed.At conception dad's 21 is added to the pair already there, while all the other chromosomes just have a pair.Cell division from conception will place the triplet 21 in every cell of the body, and the imbalance of the material leads to the features of ds. ...Read more
DNA Moon synd: Great wikipedia discussion online.Get a more detailed answer ›
Chromosome deletion: Cri du chat is a rare genetic disorder to to chromosome deletion on chromosome 5. See the good discussion of it here: https://en.wikipedia.org/wiki/Cri_du_chat Here's a great organization formed to educate and support: https://fivepminus.org/ ...Read more
Gene on X-chromosome: Hemophilia a is a hereditary bleeding disorder where there is a deficiency in clotting factor viii (factor viii is needed for blood clotting). It is inherited on the x-chromosome (sex-linked). Men only have 1 "x", so if their "x" is mutated, they will have the disease. Women have 2 "x's", so they can have 1 mutated "x" and 1 normal "x", and be a carrier of the disease, with mild or no symptoms. ...Read more
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Refsum's disease : The following link is a comprehensive review of Refum's disease by the nih. http://ghr.nlm.nih.gov/condition/refsum-disease ...Read more
See below: Most paraneoplastic neuropathies are due to immune responses to neural proteins secreted by cancer cells. Most have been associated with small cell lung cancer_ others with cancer of the ovaries, breast, lymphoma,thymine,melanoma, and testicular cancer. Symptoms can include encephalitis, cerebellar degeneration, sympathy, motor neuron disease,Gillian Barre syndrome, myopathy and Eaton-Lambert myo ...Read more
Sporadic event: The preparation of an egg for fertilization includes reducing all the chromosomes (22 regular pairs + a sex chm pair) from pairs to singles. The sperm then brings a single 1-22 regular +a sex chromosome. If the egg has a pair of 18 chms, then when the sperm adds the single 18 there is 3, this creates the chms imbalance in every skin cell of the fetus & results in the defects of edward syndrome. ...Read more
What causes turner syndrome, noonan syndrome, & the rare klippel-fell syndrome? What happens during fetal development that causes these conditions?
A genetic accident: During formation of the egg or sperm can leave out an x chromosome in either one. A fetus whose genetic make-up includes the germ cell missing a chr. X has turner syndrome. One of 8 different genetic mutations is passed on to a fetus by 1 parent or happens spontaneously to cause noonan syndrome. 2 related genetic mutations are passed on to the fetus by 1 parent to cause klippel-feil syndrome. ...Read more
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