DNA, RNA, Chromosomes, and Genes


Can people have missing or extra chromosomes?

Yes, people can live with this chromosomal abnormality, depending on which chromosomes are copied or missing; for example, Down syndrome (an extra copy of chromosome 21) and Turner syndrome (a female with only one X chromosome). Conversely, almost 1 percent of all conceptions are triploid (three copies of each chromosome), but over 99 percent of these die before birth.


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