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Diagnosis:
Trisomy 13 or Patau Syndrome
ISCN: 47,XX,+13
Discussion:
This newborn child presented with many of the common clinical findings
of Trisomy 13. Some of the most common findings in Trisomy 13 include
defects of the eyes, nose, lips, palate, ears and forebrain, scalp defects,
polydactyly with narrow hyperconvex fingernails, severe mental retardation,
microcephaly, seizures, cardiac abnormalities, and genital abnormalities.
The median survival is less than 1 week with only 5% surviving beyond
6 months.
Patau Syndrome is seen in about 1/20,000 births. About 80% of patients
with Trisomy 13 have an extra free copy of chromosome 13 (+13) resulting
from predominantly maternal meiotic nondisjunction, while the remaining
20% of patients have Trisomy 13 resulting from a Robertsonain translocation.
The recurrence risk depends upon maternal age and the mode of inheritance.
As the infant in this example had an extra free chromosome 13, 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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