Mitochondrial DNA content is associated with ploidy status, maternal age, and oocyte maturation methods in mouse blastocysts.

PURPOSE: It was reported that mitochondrial DNA (mtDNA) was significantly increased in aneuploid human embryos compared to euploid embryos and was also associated with maternal age. In this study, we further established the mouse model of mtDNA quantitation in reproductive samples based on whole-genome amplification (WGA) and next-generation sequencing (NGS). METHODS: WGA followed by NGS-based mtDNA quantitation was first performed on 6 single- and 100-cell samples from a tumor-derived mouse cell line, which was exposed to ethidium bromide to reduce mtDNA content. The relative mtDNA content was normalized to nuclear DNA. This method was then applied to mouse reproductive samples, including 40 pairs of oocytes and polar bodies from 8 CD-1 female mice of advanced reproductive age and 171 blastocysts derived via in vitro maturation (IVM) or in vivo maturation (IVO) from young (6-9 weeks) and reproductively aged (13.5 months) female CF-1 mice. RESULTS: Exposure to ethidium bromide for 3 and 6 days decreased mtDNA levels in both the single- and 100-cell samples as expected. Results demonstrated that the first polar body contained an average of 0.9% of mtDNA relative to oocytes. Compared to the cells in blastocysts, oocytes contained about 180 times as much mtDNA per cell. mtDNA levels were compared among blastocysts from reproductively young and old female mice that had either been produced by IVM or IVO. Cells in blastocysts from younger mice contained significantly lower amounts of mtDNA compared to aged mice (P < 0.0001). Cells in blastocysts produced via IVO had higher mtDNA content than IVM-derived blastocysts (P = 0.0001). Cells in aneuploid blastocysts were found to have significantly higher (1.74-fold) levels of mtDNA compared to euploid blastocysts (P = 0.0006). CONCLUSION: A reliable method for assessing mtDNA content in mouse gametes and embryos was established. Relative mtDNA levels were elevated in aneuploid embryos relative to euploid embryos, were higher in blastocysts from reproductively old mice relative to young mice, and were lower in embryos derived from IVM compared to IVO.

Evaluation of comprehensive chromosome screening platforms for the detection of mosaic segmental aneuploidy.

PURPOSE: A subset of preimplantation embryos identified as euploid may in fact possess both whole and sub-chromosomal mosaicism, raising concerns regarding the predictive value of current comprehensive chromosome screening (CCS) methods utilizing a single biopsy. Current CCS methods may be capable of detecting sub-chromosomal mosaicism in a trophectoderm biopsy by examining intermediate levels of segmental aneuploidy within a biopsy. This study evaluates the sensitivity and specificity of segmental aneuploidy detection by three commercially available CCS platforms utilizing a cell line mixture model of segmental mosaicism in a six-cell trophectoderm biopsy. METHODS: Two cell lines with known karyotypes were obtained and mixed together at specific ratios of six total cells (0:6, 1:5, 2:4, 3:3, 4:2, 5:1, and 6:0). A female cell line containing a 16.2 Mb deletion on chromosome 5 and a male cell line containing a 25.5 Mb deletion on chromosome 4 were used to create mixtures at each level. Six replicates of each mixture were prepared, randomized, and blinded for analysis by one of the three CCS platforms (SNP-array, VeriSeq NGS, or NexCCS). Sensitivity and specificity of segmental aneuploidy at each level of mosaicism was determined and compared between each platform. Additionally, an alternative VeriSeq NGS analysis method utilizing previously published criteria was evaluated. RESULTS: Examination of the default settings of each platform revealed that the sensitivity was significantly different between NexCCS and SNP up to 50% mosaicism, custom VeriSeq, and SNP-array up to 66% mosaicism, and between NexCCS and custom VeriSeq up to 50% mosaicism. However, no statistical difference was observed in mixtures with >50% mosaicism with any platform. No comparison was made between default VeriSeq, as it does not report segmental imbalances. Furthermore, while the use of previously published criteria for VeriSeq NGS significantly increased sensitivity at low levels of mosaicism, a significant decrease in specificity was observed (66% false positive prediction of segmental aneuploidy). CONCLUSION: These results demonstrate the potential of NGS-based detection methods to detect segmental mosaicism within a biopsy. However, these data also demonstrate that a balance between sensitivity and specificity should be more carefully considered. These results emphasize the importance of vigorous preclinical evaluation of new testing criteria prior to clinical implementation providing a point of departure for further algorithm development and improved detection of mosaicism within preimplantation embryos.

A randomized and blinded comparison of qPCR and NGS-based detection of aneuploidy in a cell line mixture model of blastocyst biopsy mosaicism.

PURPOSE: A subset of preimplantation stage embryos may possess mosaicism of chromosomal constitution, representing a possible limitation to the clinical predictive value of comprehensive chromosome screening (CCS) from a single biopsy. However, contemporary methods of CCS may be capable of predicting mosaicism in the blastocyst by detecting intermediate levels of aneuploidy within a trophectoderm biopsy. This study evaluates the sensitivity and specificity of aneuploidy detection by two CCS platforms using a cell line mixture model of a mosaic trophectoderm biopsy. METHODS: Four cell lines with known karyotypes were obtained and mixed together at specific ratios of six total cells (0:6, 1:5, 2:4, 3:3, 4:2, 5:1, and 6:0). A female euploid and a male trisomy 18 cell line were used for one set, and a male trisomy 13 and a male trisomy 15 cell line were used for another. Replicates of each mixture were prepared, randomized, and blinded for analysis by one of two CCS platforms (quantitative polymerase chain reaction (qPCR) or VeriSeq next-generation sequencing (NGS)). Sensitivity and specificity of aneuploidy detection at each level of mosaicism was determined and compared between platforms. RESULTS: With the default settings for each platform, the sensitivity of qPCR and NGS were not statistically different, and 100 % specificity was observed (no false positives) at all levels of mosaicism. However, the use of previously published custom criteria for NGS increased sensitivity but also significantly decreased specificity (33 % false-positive prediction of aneuploidy). CONCLUSIONS: By demonstrating increased false-positive diagnoses when reducing the stringency of predicting an abnormality, these data illustrate the importance of preclinical evaluation of new testing paradigms before clinical implementation.

Multiple thrombophilic single nucleotide polymorphisms lack a significant effect on outcomes in fresh IVF cycles: an analysis of 1717 patients.

PURPOSE: The aim of the study is to determine if thrombophilic single nucleotide polymorphisms (SNPs) affect outcomes in fresh in vitro fertilization (IVF) cycles in a large general infertility population. METHODS: A prospective cohort analysis was performed at a university-affiliated private IVF center of female patients undergoing fresh non-donor IVF cycles. The effect of the following thrombophilic SNPs on IVF outcomes were explored: factor V (Leiden and H1299R), prothrombin (G20210A), factor XIII (V34L), ß-fibrinogen (-455G → A), plasminogen activator inhibitor-1 (4G/5G), human platelet antigen-1 (a/b9L33P), and methylenetetrahydrofolate reductase (C677T and A1298C). The main outcome measures included positive pregnancy test, clinical pregnancy, embryo implantation, live birth, and pregnancy loss. RESULTS: Patients (1717) were enrolled in the study, and a total of 4169 embryos were transferred. There were no statistically significant differences in positive pregnancy test, clinical pregnancy, embryo implantation, live birth, or pregnancy loss in the analysis of 1717 patients attempting their first cycle of IVF. Receiver operator characteristics and logistic regression analyses showed that outcomes cannot be predicted by the cumulative number of thrombophilic mutations present in the patient. CONCLUSIONS: Individual and cumulative thrombophilic SNPs do not affect IVF outcomes. Therefore, initial screening for these SNPs is not indicated.

Tracking embryo implantation using cell-free fetal DNA enriched from maternal circulation at 9 weeks gestation.

Embryo DNA fingerprinting represents an important tool for tracking embryo-specific outcomes after multiple embryo transfer during IVF. The situation in which two embryos are transferred and only one implants represents a unique opportunity for the most well-controlled validation of markers capable of identifying competent and incompetent embryos. Specifically, this design eliminates all patient-related variables from the comparison of embryos with or without reproductive potential. However, in order to determine which embryo implanted, the investigator must wait until newborn DNA is available upon delivery. This study validates a non-invasive cell-free fetal DNA fingerprinting method that reduces the time to identify which embryo implanted by ∼31 weeks. Thirty-four patients were studied to determine if fingerprinting of fetal DNA extracted from maternal plasma at nine gestational weeks concurred with the buccal DNA results obtained from the newborn after delivery. This validation required single nucleotide polymorphism profiles on each couples' preimplantation embryos, cell-free fetal DNA from maternal plasma at 9 weeks gestation, and newborn DNA obtained from buccal swabs after delivery. The predictions from fetal DNA-based embryo tracking and gender assignments made at 9 weeks gestation were 100% consistent with standardized methods of assessment performed after term delivery. This study demonstrates the first validated fetal DNA fingerprinting method which predicts both gender and which embryo implanted at 9 weeks gestation following multiple embryo transfer.

The p53 codon 72 single nucleotide polymorphism lacks a significant effect on implantation rate in fresh in vitro fertilization cycles: an analysis of 1,056 patients.

OBJECTIVE: To determine whether the p53 codon 72 single nucleotide polymorphism, a change of the amino acid arginine (Arg) to proline (Pro) resulting from a single nucleotide mutation of guanine (G) to cytosine (C), has a clinically significant effect on implantation rate in fresh IVF cycles. DESIGN: Prospective cohort analysis. SETTING: University-affiliated private IVF center. PATIENT(S): One thousand fifty-six female patients undergoing fresh nondonor IVF cycles. MAIN OUTCOME MEASURE(S): Embryo implantation rate. RESULT(S): Of the 1,056 patients (2,600 total embryos transferred) undergoing their first IVF cycle, 289 had no implantation events and attempted a second cycle. Of the 289 patients in their second cycle, 72 had no implantation events and attempted a third cycle. The p53 codon 72 single nucleotide polymorphism frequencies in the first cycle (homozygous major allele Arg/Arg [G_G] = 45%, heterozygous allele Arg/Pro [G_C] = 44%, and homozygous minor allele Pro/Pro [C_C] = 11%) did not differ significantly across subsequent IVF cycles. There was no statistically significant difference in embryo implantation rate with respect to the single nucleotide polymorphism. CONCLUSION(S): The p53 codon 72 single nucleotide polymorphism lacks a clinically significant effect on embryo implantation rate in patients undergoing fresh nondonor IVF cycles.