mily medical histories.
             However, Downs Syndrome can only be traced, through families of, less than 1% of people with the condition. These people all have rare types of Translocation (see bullet point 2, for explanation of this type) (Carr, 1995).
             This could suggest that it is very unusual for parents to have more than one Downs Syndrome child or for relatives of these parents to also have a child with the condition.
             Regular Trisomy 21 occurs when an unusual cell division has taken place, which has produced either an egg or a sperm with 24 chromosomes instead of 23. When this egg or sperm fuses with an ordinary egg or sperm, the first cell of the developing baby has 47 chromosomes instead of 46. This will then leave the child's cells with 47 chromosomes.
             There is no way of predicting whether a person is more or less likely to produce eggs or sperm with 24 chromosomes (Carr, 1995). The extra
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