What are the causes of down syndrome?

Answer 1

Downs syndrome is in medical terms called Trisomy 21 as it is caused by a genetic defect in the 21st set of chromosome, usually you have 44 chromosomes - 22 from your mother and 22 from your father and a set of sex chromosomes (these are your male/female genes), if you have Down syndrome you have an extra chromosome on the 21st set of genes so instead of 1 from each parent you have 1 from you dad, 1 from your mum and a mutated gene.

Answer 2

The cause of Down syndrome is one of three types of abnormal cell division involving chromosome 21. All three abnormalities result in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of Down syndrome. The three genetic variations that can cause Down syndrome include:

• Trisomy 21. More than 90 percent of cases of Down syndrome are caused by trisomy 21. A child with trisomy 21 has three copies of chromosome 21 - instead of the usual two copies - in all of his or her cells. This form of Down syndrome is caused by abnormal cell division during the development of the sperm cell or the egg cell.
• Mosaic Down syndrome. In this rare form of Down syndrome, children have some cells with an extra copy of chromosome 21. This mosaic of normal and abnormal cells is caused by abnormal cell division after fertilization.
• Translocation Down syndrome. Down syndrome can also occur when part of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception. Children with translocation Down syndrome have the usual two copies of chromosome 21, but they also have additional material from chromosome 21 stuck to the translocated chromosome. This form of Down syndrome is uncommon.

There are no known behavioral or environmental factors that cause Down syndrome.

Answer 3

There are many causes for Down Syndrome. One of the cause is:

Nondisjunction : The body's cells contains nucleus which has 23 pairs of chromosomes; the nucleus is storage for genetic material (genes). The occurence of Nondisjunction is mainly caused by an error in cell division and an embryo ends up with three copies of chromosome 21 instead of two. In conception the 21st chromosome in a sperm or egg can have an abnormal cell division and as the embryo grows the additional chromosome maybe copied to the rest of the body's cells. Nondisjunction mainly causes Down syndrome type called Trisomy 21. The risk of nondisjunction in women increases as age passes.

Answer 4

Down's Syndrome is the unfortunate effect of an error that takes place during cell division at fertilisation. The error leads the child to have an extra 21st chromosone which causes cognitive and physical impairments.

Answer 5

an abnormality of the splitting of the chromosomes

Answer 6

Down syndrome is a chromosomal disorder caused by an error in cell division that results in an extra 21st chromosome

Answer 7

Nondisjunction

Answer 8

non-disjunction