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Down syndrome (aka trisomy 21) is caused when an extra chromosone number 21 is present.
Normally, each cell in your body has two copies of each of the 44 regular chromosomes, one X and another X (in women) or a Y (in men). When sperm and eggs are formed these pairs line up and then are divided into two sets of 23 chromosomes, one of each.
In the most common form of Down Syndrome the pairs of chromosone 21 do not seperate making a sperm or egg with two and another with none. If the sperm or egg with two participates in ferilization the result is a cell with 3 chromosome number 21's (2 from one parent and 1 from the other). This type tends to happen more often as women get older. It is not nearly as strongly related to the age of the father.
In a less common form one of the parents has a chromosome 21 that is duplicated and stuck to itself and so twice as large (a Robertsonian translocation). The person with this defect may be an apparently normal carrier but produce children (and grand children) with Down's.
Wiki User
∙ 12y ago
Wiki User
∙ 12y agoit is caused by an extra chromosome 21
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Is down syndrome caused by premature birth?
Down syndrome is not caused by premature birth. Down syndrome is present in the embryo from the time of conception. Down syndrome, in contrast, may lead to premature birth.
What can down syndrome be caused by?
Down's Syndrome is caused mainly by a mutation in the gene. It is a genetic disorder, which means it was passed on from parents to offspring.
Does antibiotics cause down syndrom?
Down syndrome is not caused by a bacterial infection therefore the answer to your question is no. Down syndrome is caused by an extra chromosome in the cell nucleus.
What human disease is caused by non-disjunction?
Down's syndrome is the most common.
What trisomy causes Down syndrome?
Down syndrome is caused by the presence of a third chromosome 21
Is down syndrome and pku caused by chromosomal abnormalities?
Down syndrome is caused by an additional chromosome while PKU is due to a mutation or defect in a gene.
Can celexa cause down syndrome?
No, down syndrome is caused by a genetic defect where there is an extra chromosome in most,if not all, of the cells of a body. it is not caused by a drug.
How do you spell downsindrowm?
The phrase is spelled Down Syndrome. Down Syndrome is a disorder caused by a mutation of the chromosomes.
Is down syndrome a mutation?
Down Syndrome is caused by extra genetic material on Chromosome 21. About half of the children of people who have Down Syndrome are born with Down Syndrome themselves. See the Related Linksbelow to view an article about the genetics of Down Syndrome.
What is the most common cause for down syndrome?
Down's syndrome is a disorder caused by defective genes. It is most commonly caused by parents who are elderly at the time of birth.
Is down syndrome cause by dominant or recessive?
Down syndrome is neither caused by dominant or recessive chromosomes it is simply caused by an error in the translation process of chromosome 21.
What condition results when a child is born with an extra chromosome on the third pair?
Down syndrome
