ABSTRACT

The analysis of products of conception (POC) is clinically important to establish the cause of early pregnancy loss. Data from such analyses can lead to specific interventions in subsequent natural or assisted conceptions. The techniques available to examine the chromosomal composition of POC have limitations and can give misleading results when maternal cell contamination (MCC) is overlooked. The aim of this study was to develop a protocol for MCC assessment and to formulate POC material handling, testing, and reporting recommendations. Using array comparative genomic hybridization, we tested 86 POC samples, of which 47 sample pairs (DNA extracted from the POC sample and maternal DNA) were assessed for the presence of MCC. MCC was evaluated using an approach we developed, which exploited the genotyping of 14 STR, AMEL, and SRY loci. POC samples showing the clear presence of villi (63.9%) did not contain any signs of the maternal genome and can therefore be reliably tested using conventional methods. The proportion of 46,XX karyotype in the unselected sample batch was 0.39, which fell to 0.23 in visually good samples and was 0.27 in samples having no signs of contamination upon MCC testing. MCC assessment can rescue visually poor samples from being discarded or wrongly genotyped. We demonstrate here that classification based on visual POC material evaluation and MCC testing leads to predictable and reliable POC genetic testing outcomes. Our formulated recommendations covering POC material collection, transportation, primary and secondary processing, as well as the array of pertinent considerations discussed here, can be implemented by laboratories to improve their POC genetic testing practices. We anticipate our protocol for MCC assessment and recommendations will help reduce the misconception regarding the etiology of miscarried fetuses and foster informed decision-making by clinicians and patients dealing with early pregnancy loss.

摘要

受孕产物 (POC) 的分析对于确定早期流产的原因具有重要的临床意义。来自此类分析的数据可以导致对随后的自然或辅助受孕进行特定干预。可用于检查 POC 染色体组成的技术具有局限性，并且在忽视母体细胞污染 (MCC) 时可能会产生误导性结果。本研究的目的是制定 MCC 评估方案并制定 POC 材料处理、测试和报告建议。使用阵列比较基因组杂交，我们测试了 86 个 POC 样本，其中 47 个样本对（从 POC 样本中提取的 DNA 和母体 DNA）评估了 MCC 的存在。MCC 使用我们开发的方法进行评估，该方法利用了 14 个 STR、AMEL 和 SRY 基因座的基因分型。显示明显存在绒毛的 POC 样本 (63.9%) 不包含任何母体基因组的迹象，因此可以使用常规方法进行可靠的测试。未选择的样品批次中 46,XX 核型的比例为 0.39，在视觉良好的样品中降至 0.23，在 MCC 测试中没有污染迹象的样品中为 0.27。MCC 评估可以挽救视觉不佳的样本，以免被丢弃或错误地进行基因分型。我们在此证明基于视觉 POC 材料评估和 MCC 测试的分类导致可预测和可靠的 POC 基因检测结果。我们制定的建议涵盖 POC 材料收集、运输、初级和二级加工，以及此处讨论的一系列相关考虑因素，可以由实验室实施，以改进他们的 POC 基因检测实践。我们预计我们的 MCC 评估方案和建议将有助于减少对流产胎儿病因的误解，并促进临床医生和处理早期妊娠丢失的患者做出明智的决策。