Reproductive consequences of genome-wide paternal uniparental disomy mosaicism: description of two cases with different mechanisms of origin and pregnancy outcomes.

Objective: To describe the molecular and cytogenetic characterization of two different prenatal cases of androgenetic/biparental mosaicism and review the different possible mechanisms of origin in each case.
Design: Case study and literature review.
Setting: Tertiary medical center (prenatal diagnosis unit).
Patient(s): A 26-year-old pregnant woman referred for suspected partial mole placenta and a 33-year-old pregnant woman referred for polyhydramnios and fetal malformations.
Intervention(s): Ultrasound examination, prenatal invasive procedures, molecular and cytogenetic analysis, physical and pathologic evaluation, and genetic counseling.
Main Outcome Measure(s): Cytogenetic analysis, fluorescent in situ hybridization, and quantitative fluorescence polymerase chain reaction (QF-PCR) analysis.
Result(s): The finding of a normal karyotype together with a triploidy-like QF-PCR profile led to the diagnosis of two cases of androgenetic (genome-wide paternal uniparental disomy)/biparental mosaicism. The first case showed placental mesenchymal dysplasia and a normal fetus, and the second one presented a fetus showing Beckwith-Wiedemann syndrome features and an apparently normal placenta.
Conclusion(s): These cases highlight the wide range of possible clinical presentations of androgenetic/biparental mosaicism, the variety of mechanisms of their origin, and the importance of the combination of molecular and cytogenetic analysis to achieve an accurate diagnosis and provide reproductive counseling.