Triploidy

Epidemiology and Etiology:

• may be XXX, XXY, XYY
• diandric (partial mole):
• 2 sets are from the father and 1 from the mother (could still be XXX, XXY, XYY)
• digynic:
• 2 sets are from the mother and 1 from the father

Common sites:

Gross features:

• Diandric:
• Placenta large with some cystic changes
• Low birth weight (symmetric IUGR)
• Disproportionately small trunk to head size
• Syndactyly
• Multiple other anomalies
• Tend to “present” in 1^st trimester
• Digynic:
• Placenta is small
• Asymmetric IUGR
• Tend to “present” in 2^nd trimester

Histologic features:

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

Other features:

• Ultrasound:
• Asymmetric IUGR
• Ventriculomegaly
• Heart defects
• 3-4 syndactyly
• neural tube defects
• molar placenta (diandry)

References:

· Evans MI, ed. Prenatal Diagnosis (2006)