Here is an example of trisomy 16. This is one of the most common chromosomal abnormalities, but the affected embryos or fetuses NEVER survive past the first trimester. Many first trimester fetuses are lost in this fashion (many are "silent" abortions). Note in this case that a sex chromosome is missing as well. Spontaneous abortion and intrauterine demise are nature's ways of eliminating abnormal karyotypes.

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