[1024] Tissue DNA Genotyping of Hydatidiform Moles: Practical and Reliable Diagnosis

F Lipata, M Martel, LH Hao, V Parkash, P Hui. Yale University School of Medicine, New Haven, CT

Background: Hydatidiform moles are defined at the genetic level by their unique parental chromosome contributions, and genotyping analysis promises to offer ultimate confirmation and subclassification of these lesions. We report our experience of DNA genotyping in the routine workup of hydatidiform moles in the past 20 months.
Design: Consecutive cases of product of conception that had undergone DNA genotyping in the past 20 months were retrieved from our pathology files. All cases had initial tissue diagnoses and sufficient DNA materials were extracted from formalin-fixed paraffin embedded tissue sections of both chorionic villi and maternal gestational endometrium. DNA genotyping was performed using a multiplex PCR reaction targeting 15 tetrameric polymorphic loci of the human genome, and the PCR product was analyzed by capillary electrophoresis.
Results: A total of 118 products of conception were included in this study. All had initial diagnoses with variable certainties of molar pregnancy. DNA genotyping was successful in all, leading to the final identification of 36 cases of hydatidiform moles. Among 13 complete moles, 9 cases were monospermic and 4 cases were dispermic at the genomic level. Twenty-three cases were confirmed by genotyping as triploid partial moles, all of which were dispermic and monogynic. Among nonmolar cases, 9 gestations were confirmed to have chromosomal trisomy syndromes: trisomy 16 (3 cases), trisomy 21(3 cases), trisomy 8 (1 case), trisomy 7 (1 case) and combined trisomy 8 and 21 (1 case). More complex chromosomal abnormalities were seen in 2 cases and 1 case was proven as digynic nonmolar triploidy. The remaining 65 cases were balanced biallelic gestations.
Conclusions: Replacing both p57 immunohistochemistry and DNA ploidy analysis, tissue DNA genotyping is a practical and highly accurate method for the confirmation and subclassification of hydatidiform moles and beyond. Our results further advocate a routine application of this one-stop shopping approach in the workup of hydatidiform moles.
Category: Gynecologic

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 160, Tuesday Afternoon