Objective: To estimate whether tissue DNA genotyping is effective for the confirmation and subclassification of hydatidiform moles.
Methods: Consecutive cases of products of conception were selected based on histologic alterations that are suspicious for molar pregnancy. DNA genotyping was performed by a multiplex polymerase chain reaction targeting 15 tetrameric polymorphic loci of the human genome.
Results: A total of 205 products of conception were included. DNA genotyping was informative in all, leading to the final identification of 60 cases of hydatidiform moles, including 17 complete and 43 partial moles. Among 17 cases of complete moles, 14 cases were monospermic and three were dispermic. Forty-three cases were confirmed as triploid partial moles, 42 of which were dispermic and one was monospermic. Among nonmolar cases, 32 gestations showed allelic changes indicating chromosomal alterations, including 28 cases of trisomy syndrome: trisomy 16 (eight cases), trisomy 21 (six cases), trisomy 7 (three cases), trisomy 13 (three cases), trisomy 4 (one case), trisomy 8 (one case), trisomy 18 (one case), XXY/Klinefelter syndrome (one case), and multiple trisomies (four cases). Monosomy 22 was seen in one case. Two nonmolar cases were triploid digynic-monoandric gestations. More complex chromosomal abnormalities were seen in one case. The remaining 113 cases were balanced biallelic gestations.
Conclusion: Tissue DNA genotyping is a practical and highly accurate method for the confirmation and subclassification of hydatidiform moles.
Level of evidence: III.