Trisomy 18
Edwards Syndrome. This karyotype demonstrates
trisomy 18 (47, XY, +18). It is uncommon for fetuses with this condition
to survive, so the incidence is only 1 in 8000 live births. Thirty percent
of these children die within the first month and only 10% survive one year.
It is rare for babies to survive for very long if liveborn because of the
multitude of anomalies that are usually present. There is severe mental
retardation and a highly characteristic pattern of malformations such as
elongated skull, a very narrow pelvis, rocker bottom feet and a grasping
of the two central fingers by the thurm and little finger. In addition,
the ears are often low set and the mouth and teeth are small. Nearly all
babies born with this condition die in early infancy.
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