Human medical cytogenetics:
Chromosomal syndromes in spontaneous abortions & live births
At least 15% of all human
conceptuses are aborted spontaneously in
the first trimester. Half of these have detectable
cytogenetic anomalies. About 0.6% of live births
exhibit one of a variety of recognized cytogenetic
syndromes. The most common are Klinefelter Syndrome
(XYY males: 28%
of total), Down Syndrome (trisomy of Chromosome
21: 20% of total), and Turner Syndrome (monosomy of the X
chromosome in women: 8% of total). A large
proportion of conceptuses with aneuploidy are aborted
spontaneously: for Trisomy 21, the ratio is 3,510
: 1,041 in abortuses versus live births. The
numbers are based on data from Sankaranarayanan
(1979) and reflect ability to detect early
spontaneous abortion at that time. More recent research
based on earlier detection suggests that >30% of
conceptuses are aborted spontaneously.
Note on Names: The three syndromes mentioned are named after the physicians who first described them. Current practice recognizes that John Langdon Down neither had the syndrome nor owned it. It is thus incorrect to call it "Down's Syndrome" and the accepted term is "Down Syndrome". The same principle applies to other chromosomal syndromes.
Note on Names: The three syndromes mentioned are named after the physicians who first described them. Current practice recognizes that John Langdon Down neither had the syndrome nor owned it. It is thus incorrect to call it "Down's Syndrome" and the accepted term is "Down Syndrome". The same principle applies to other chromosomal syndromes.