Circulating Cell-Free DNA in the Diagnosis of Hydatidiform Mole and Digynic Nonmolar Triploidy
Prenatal Genetics
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Primary Categories:
- Prenatal Genetics
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Secondary Categories:
- Prenatal Genetics
Introduction:
Hydatidiform mole (HM) and digynic nonmolar triploidy represent significant challenges in prenatal care, given their distinct chromosomal origins and the limitations of conventional diagnostic methods. Circulating cell-free DNA (cfDNA) has emerged as a promising non-invasive tool for the early detection of these gestational abnormalities, offering improved diagnostic accuracy, especially in cases where traditional imaging and histopathology may be inconclusive. This study investigates the potential of cfDNA analysis to distinguish between hydatidiform moles, characterized by an extra set of paternal chromosomes with abnormal trophoblastic proliferation, and digynic nonmolar triploidy, where an extra set of maternal chromosomes results in a nonviable fetus without molar characteristics.
Methods:
We developed a cfDNA screening protocol using high-coverage next-generation sequencing for targeted nucleotide polymorphism analysis, extracting cfDNA from maternal plasma prior to uterine evacuation. This method enabled comprehensive genome assessment of products of conception (POC), allowing ploidy estimation and precise genetic characterization without invasive sampling. All cfDNA findings were cross-validated against additional short tandem repeat polymorphism (STR) analysis results of POC samples.
Results:
Sixteen patients with HM and 20 patients with digynic nonmolar triploidy confirmed by STR analysis were included in this study. All 36 cases in this study were initially diagnosed as embryonic arrest/miscarriage before surgical intervention. Only 7 cases (7/36, 19.4%) were correctly diagnosed based on morphological and immunohistochemical examination of POC, all of which were morphologically distinct complete HMs. The proportion of cfDNA derived from gestational trophoblasts of HMs ranged from 0 to 41.1%, with 14 cases (14/16, 87.5%) showing detectable cfDNA fractions above 0%. Among these, cfDNA analysis identified 4 HMs comprising 2 cases of complete HMs (homozygous diploid) and 2 cases of partial HMs (dispermous triploid). In digynic nonmolar triploidy cases, the cfDNA proportion ranged from 0 to 46.1%, with 11 cases (11/20, 55.0%) showing detectable cfDNA. Furthermore, 2 cases of digynic nonmolar triploidy were identified. All cfDNA diagnostic results match the STR of the POC, demonstrating the utility of allele fraction distribution for the non-invasive diagnosis of rare gestational abnormalities.
Conclusion:
This study introduces a cfDNA-based methodology for the genetic evaluation of POC, offering diagnostics for distinguishing HMs and digynic nonmolar triploidy in cases where traditional methods fail. The ability to identify and characterize these abnormalities non-invasively holds transformative potential for prenatal care, enabling timely and accurate interventions in complex gestational presentations. Further advancements are necessary to enhance the detectability of samples with extremely low but detectable fetal fractions, thereby improving the clinical applicability and reliability of this method.
Hydatidiform mole (HM) and digynic nonmolar triploidy represent significant challenges in prenatal care, given their distinct chromosomal origins and the limitations of conventional diagnostic methods. Circulating cell-free DNA (cfDNA) has emerged as a promising non-invasive tool for the early detection of these gestational abnormalities, offering improved diagnostic accuracy, especially in cases where traditional imaging and histopathology may be inconclusive. This study investigates the potential of cfDNA analysis to distinguish between hydatidiform moles, characterized by an extra set of paternal chromosomes with abnormal trophoblastic proliferation, and digynic nonmolar triploidy, where an extra set of maternal chromosomes results in a nonviable fetus without molar characteristics.
Methods:
We developed a cfDNA screening protocol using high-coverage next-generation sequencing for targeted nucleotide polymorphism analysis, extracting cfDNA from maternal plasma prior to uterine evacuation. This method enabled comprehensive genome assessment of products of conception (POC), allowing ploidy estimation and precise genetic characterization without invasive sampling. All cfDNA findings were cross-validated against additional short tandem repeat polymorphism (STR) analysis results of POC samples.
Results:
Sixteen patients with HM and 20 patients with digynic nonmolar triploidy confirmed by STR analysis were included in this study. All 36 cases in this study were initially diagnosed as embryonic arrest/miscarriage before surgical intervention. Only 7 cases (7/36, 19.4%) were correctly diagnosed based on morphological and immunohistochemical examination of POC, all of which were morphologically distinct complete HMs. The proportion of cfDNA derived from gestational trophoblasts of HMs ranged from 0 to 41.1%, with 14 cases (14/16, 87.5%) showing detectable cfDNA fractions above 0%. Among these, cfDNA analysis identified 4 HMs comprising 2 cases of complete HMs (homozygous diploid) and 2 cases of partial HMs (dispermous triploid). In digynic nonmolar triploidy cases, the cfDNA proportion ranged from 0 to 46.1%, with 11 cases (11/20, 55.0%) showing detectable cfDNA. Furthermore, 2 cases of digynic nonmolar triploidy were identified. All cfDNA diagnostic results match the STR of the POC, demonstrating the utility of allele fraction distribution for the non-invasive diagnosis of rare gestational abnormalities.
Conclusion:
This study introduces a cfDNA-based methodology for the genetic evaluation of POC, offering diagnostics for distinguishing HMs and digynic nonmolar triploidy in cases where traditional methods fail. The ability to identify and characterize these abnormalities non-invasively holds transformative potential for prenatal care, enabling timely and accurate interventions in complex gestational presentations. Further advancements are necessary to enhance the detectability of samples with extremely low but detectable fetal fractions, thereby improving the clinical applicability and reliability of this method.