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is a combination of birth defects including some degree of mental retardation and characteristic facial features. It is also called trisomy 21. occurs when there is an abnormality in chromosome 21. It is found in approximately 1 out of 1000 all live births. ....

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.... was dropped from scientific use. Instead, the condition became called "Down's syndrome." In the 1970s, an American revision of scientific terms changed it simply to "," while it still is called "Down's" in Europe. There are three main types of . The vast majority of children with (approximately 95 percent) have an extra 21 chromosome. Instead of the normal number of 46 chromosomes in each cell, the individual with has 47 chromosomes. This condition is called trisomy 21. The second type is called translocation since the extra 21 chromosome is attached or translocated on to another chromosome, usually on chromosome 14, 21 or 22. If translocation is ....