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). Note that a large fraction of
conceptuses with Trisomy
21 and XO are
aborted spontaneously. The figure is based on data from Sankaranarayanan
(1979) ; current research and earlier detection
suggests that 30% or more 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 principal applies to other medical conditions.
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 principal applies to other medical conditions.