Is down syndrome when you have an extra chromosome

How does someone with Down syndrome get that extra chromosome??

http://wiki.answers.com/Q/How_does_person_with_down_syndrome_have_an_extra_chromosome

During meiosis homologous chromosomes are separated and only one copy of each chromosome goes into the gamete. If they aren’t separated correctly, both copies may go into the gamete. After fertilisation, the embryo will contain 3 copies of …

What causes a baby to have an extra chromosome as in Down syndrom…?

http://www.dshs.state.tx.us/genetics/info%20and%20ed.shtm

Down syndrome is a genetic condition that is caused by an extra copy of the 21st chromosome. Before parents can make a baby, certain cells in the ovaries and sperm must divide so that the child does not get too much DNA. Each cell that will…

What happens when there are two extra chromosome in Down’s syndro…?

http://answers.yahoo.com/question/index?qid=20081008094051AARunjU

Chromosomes are the units of genetic information that exist within every cell of the body. Twenty-three distinctive pairs, or 46 total chromosomes, are located within the nucleus (central structure) of each cell. When a baby is conceived by…

Related Questions Answered on Y!Answers

How to get an extra chromosome/Down Syndrome?

Q: I am wondering if there is a way to gain an extra chromosome, hopefully resulting in getting the Down Syndrome condition. Or just a way to get Down Syndrome directly. I believe in Retard Supremacy and I believe that all cogno-normatives are soon to fade from existence and I would like to receive the gift of retardation before this happens. No I am not joking, I am serious so please don’t troll me. I just want to be a retard, the more severe the better. I wish I had Down Syndrome.

A: …..uhhh……wtf?….i think in posting this question…you’ve reached ur goal of being a retard…

Most people who have down syndrome have an extra copy of chromosome 21 (trisomy 21)?

Q: Most people who have down syndrome have an extra copy of chromosome 21 (trisomy 21), which is a result of an egg or sperm that carried an extra copy of chromosome 21. How could a gamete with an extra chromosome come about?

A: Nondisjunction, an “accident” during meiosis. See the link.

What happens when there are two extra chromosome in Down’s syndrome?

Q:

A: Chromosomes are the units of genetic information that exist within every cell of the body. Twenty-three distinctive pairs, or 46 total chromosomes, are located within the nucleus (central structure) of each cell. When a baby is conceived by the combining of one sperm cell with one egg cell, the baby receives 23 chromosomes from each parent, for a total of 46 chromosomes. Sometimes, an accident in the production of a sperm or egg cell causes that cell to contain 24 chromosomes. This event is referred to as nondisjunction. When this defective cell is involved in the conception of a baby, that baby will have a total of 47 chromosomes. The extra chromosome in Down syndrome is labeled number 21. For this reason, the existence of three such chromosomes is sometimes referred to as Trisomy 21.In a very rare number of Down syndrome cases (about 1-2%), the original egg and sperm cells are completely normal. The problem occurs sometime shortly after fertilization; during the phase where cells are dividing rapidly. One cell divides abnormally, creating a line of cells with an extra chromosome 21. This form of genetic disorder is called a mosaic. The individual with this type of Down syndrome has two types of cells: those with 46 chromosomes (the normal number), and those with 47 chromosomes (as occurs in Down syndrome). Some researchers have suggested that individuals with this type of mosaic form of Down syndrome have less severe signs and symptoms of the disorder.Another relatively rare genetic accident which can cause Down syndrome is called translocation. During cell division, the number 21 chromosome somehow breaks. A piece of the 21 chromosome then becomes attached to another chromosome. Each cell still has 46 chromosomes, but the extra piece of chromosome 21 results in the signs and symptoms of Down syndrome. Translocations occur in about 3-4% of cases of Down syndrome.Down syndrome occurs in about one in every 800-1,000 births. It affects an equal number of boys and girls. Less than 25% of Down syndrome cases occur due to an extra chromosome in the sperm cell. The majority of cases of Down syndrome occur due to an extra chromosome 21 within the egg cell supplied by the mother (nondisjunction). As a woman’s age (maternal age) increases, the risk of having a Down syndrome baby increases significantly. For example, at younger ages, the risk is about one in 4,000. By the time the woman is age 35, the risk increases to one in 400; by age 40 the risk increases to one in 110; and by age 45 the risk becomes one in 35. There is no increased risk of either mosaicism or translocation with increased maternal age.