question about down syndrome?

Why is it that people with down syndrome all look the same? Is it something about genetics?

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  • 1 decade ago
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    Yes, it is genetics. People with Down syndrome have an extra 21st chromosome. There are three different types of Down syndrome. The three forms are trisomy 21, translocation, and mosaic. In most cases the individual will have trisomy 21. This is where the child has an extra 21 chromosome. This results in a total of 47 chromosomes instead of the typical 46.

    The second type of Down syndrome is called translocation. The extra 21st chromosome is attached or translocated onto another chromosome, usually on chromosome 14, 21 or 22.

    The third type of Down syndrome is mosaic. In this case, some cells have 47 chromosomes and others have 46 chromosomes.

    It was the common facial features of Down syndrome that led John Langdon Down to publish an accurate description of a person with Down syndrome. Down discovered Down syndrome in 1866, although he did not know the cause of the syndrome.

  • 1 decade ago

    Suffers of downs syndrome have 3 copies of chromosome 21. Although the effects of this can vary greatly between individuals, generally they share characteristics, as you would expect with a common genetic defect.

  • 1 decade ago

    yes. the extra 21st chromosome causes the down's syndrome and the physical attributes that go along with it.

  • 1 decade ago

    www.cnn.com/HEALTH/library/DS/00182.html

    en.wikipedia.org/wiki/Down_syndrome

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