Down Syndrome - Cause
is caused by abnormal cell division in early
embryo development. Normally, a child inherits 46
chromosomes, 23 from each parent. Each chromosome carries DNA, called genes, which tell how the brain and body should develop.
But a fetus with Down
syndrome has extra or abnormal chromosomes. Having extra genetic material changes the way the brain and body develop. The type of Down
syndrome depends on how many cells have the extra or abnormal chromosomes.
Medical experts believe the cell changes most
often start in a woman's egg before or at conception. Less often, the error
occurs in sperm at conception. It is not known what causes the cells to divide
abnormally. One type of Down syndrome, called translocation-type, may be
passed down through families (inherited).