Diagnosis: Trisomy 13 or Patau Syndrome

ISCN: 46,XX,+13,der(13;14)(q10;q10)mat or 46,XX,+13,rob(13;14)(q10;q10)mat

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 chromosome 13 resulting from a Robertsonian translocation, peripheral blood chromosome analysis of the parents was recommended. The father had a normal karyotype; the mother's karyotype is shown in unknown 5. 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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