[Clinical application of STR genotyping diagnosis for hydatidiform mole and nonmolar gestation]

Objective: To investigate the value of short tandem repeat (STR) genotyping in the diagnostic workup of molar and non-molar gestations with correlation of histological characteristics. Methods: Six hundred and fifty-six cases were selected based on clinically suspected hydropic abortion and/or molar pregnancy from July 2015 to September 2017 at Beijing Obstetrics and Gynecology Hospital. DNA was extracted from dissected chorionic villi and paired maternal endometrial FFPE tissue samples by Simplex OUP™ FFPE DNA Tissue Kit. STR genotyping was performed by PowerPlex 16 HS system. Results: DNA genotyping was informative in 649 of 656 cases, leading to identification of 215 hydatidiform mole gestations and 434 non-molar gestations. Most of non-molar gestations (375 cases, 86.4%) were diploid hydropic abortion. Various trisomy syndromes were found (53 cases, 12.2%), including trisomy 2, 3, 4, 7, 8, 13, 16 and 21. Only 2(0.5%) digynic triploid gestations were detected. Moreover, 4 cases (0.9%) of uniparental disomies (homologous or heterologous) were found. There were 196 cases with histologic diagnostic suspicious of hydatidiform moles were accurate sub-classified. Among them, 59 cases hydatidiform moles were under-diagnosed as diploid hydropic abortions, and 28 cases diploid hydropic abortions were over-diagnosed as hydatidiform moles.Compared with partial moles(PHM), there were no specific histomorphological features between the various types of non-molar gestations and partial moles for definitive diagnostic separation. There was no significant difference in the expression of p57(kip2) among PHM, trisomy and diploid hydropic abortions group (P=0.247). Conclusions: STR genotyping can distinguish non-molar gestations from early hydatidiform moles, and efficiently avoid misdiagnosis based only on histological evaluation. Therefore, using STR genotyping, not only can the overdiagnosis of non-molar pregnancy be avoided, but also individualized management can be offered to patients including monitoring of serum hCG.