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Diagnosis: Trisomy
18 or Edward Syndrome
ISCN:
47,XY,+18
Discussion:
This newborn presented with many of the common findings of Trisomy 18.
Some of the most common findings of Trisomy 18 include small, clenched
hands with overlapping fingers, short sternum, prominent occiput, abnormal
ears, small mouth, micrognathia, small nipples, inguinal or umbilical
hernias, redundant skin, and cardiac abnormalities. The median survival
is about 1 week with less than 10% surviving beyond 1 year.
Trisomy 18 is seen in about 1/6,000 births. The vast majority of cases
of Trisomy 18 are secondary to maternal meiotic nondisjunction. The recurrence
risk varies with maternal age.
As the newborn in this example had an extra chromosome 18, resulting from
nondisjunction, karyotyping of the parents was not indicated. Genetic
counseling of the parents was recommended to explain the cause of this
infant's chromosomal abnormality and the recurrence risk for future pregnancies.
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