First systematic experience of preimplantation genetic diagnosis for single-gene disorders, and/or preimplantation human leukocyte antigen typing, combined with 24-chromosome aneuploidy testing.

OBJECTIVE: To study the feasibility, accuracy, and reproductive outcome of 24-chromosome aneuploidy testing (24-AT), combined with preimplantation genetic diagnosis (PGD) for single-gene disorders (SGDs) or human leukocyte antigen (HLA) typing in the same biopsy sample. DESIGN: Retrospective study. SETTING: Preimplantation genetic diagnosis center. PATIENT(S): A total of 238 PGD patients, average age 36.8 years, for whom 317 combined PGD cycles were performed, involving 105 different conditions, with or without HLA typing. INTERVENTION(S): Whole-genome amplification product, obtained in 24-AT, was used for PGD and/or HLA typing in the same blastomere or blastocyst biopsy samples. MAIN OUTCOME MEASURE(S): Proportion of the embryos suitable for transfer detected in these blastomere or blastocyst samples, and the resulting pregnancy and spontaneous abortion rates. RESULT(S): Embryos suitable for transfer were detected in 42% blastocyst and 25.1% blastomere samples, with a total of 280 unaffected, HLA-matched euploid embryos detected for transfer in 212 cycles (1.3 embryos per transfer), resulting in 145 (68.4%) unaffected pregnancies and birth of 149 healthy, HLA-matched children. This outcome is significantly different from that of our 2,064 PGD cycle series without concomitant 24-AT, including improved pregnancy (68.4% vs. 45.4%) and 3-fold spontaneous abortion reduction (5.5% vs. 15%) rates. CONCLUSION(S): The introduced combined approach is a potential universal PGD test, which in addition to achieving extremely high diagnostic accuracy, significantly improves reproductive outcomes of PGD for SGDs and HLA typing in patients of advanced reproductive age.

Meiosis errors in over 20,000 oocytes studied in the practice of preimplantation aneuploidy testing.

This study presents the world's largest series of over 20,000 oocytes tested for aneuploidies, involving chromosomes 13,16, 18, 21 and 22, providing the data on the rates and types of aneuploidies and their origin. Almost every second oocyte (46.8%) is abnormal, with predominance of extra chromatid errors predicting predominance of trisomies (53%) over monosomies (26%) in the resulting embryos (2:1), which is opposite to monosomy predominance observed in embryo testing. Of the detected anomalies in oocytes, 40% are complex, so testing for a few most prevalent chromosome errors may allow detection of the majority of abnormal embryos. Chromosome 21 and 22 errors are more prevalent, while two different patterns of error origin were observed for different chromosomes: chromosome 16 and 22 errors originate predominantly from meiosis II, compared with chromosome 13, 18 and 21 errors originating from meiosis I. This provides the first evidence for the differences in the aneuploid embryo survival depending on the meiotic origin. Considering the problem of mosaicism, which is the major limitation of the cleavage-stage testing, the direct oocyte aneuploidy testing by polar body analysis may be of obvious practical value in improving accuracy and reliability of avoiding aneuploid embryos for transfer.

Conversion and non-conversion approach to preimplantation diagnosis for chromosomal rearrangements in 475 cycles.

Due to the limitations of preimplantation genetic diagnosis (PGD) for chromosomal rearrangements by interphase fluorescent in-situ hybridization (FISH) analysis, a method for obtaining chromosomes from single blastomeres was introduced by their fusion with enucleated or intact mouse zygotes, followed by FISH analysis of the resulting heterokaryons. Although this allowed a significant improvement in the accuracy of testing of both maternally and paternally derived translocations, it is still labour intensive and requires the availability of fertilized mouse oocytes, also creating ethical issues related to the formation of interspecies heterokaryons. This method was modified with a chemical conversion procedure that has now been clinically applied for the first time on 877 embryos from PGD cycles for chromosomal rearrangements and has become the method of choice for performing PGD for structural rearrangements. This is presented within the context of overall experience of 475 PGD cycles for translocations with pre-selection and transfer of balanced or normal embryos in 342 (72%) of these cycles, which resulted in 131 clinical pregnancies (38%), with healthy deliveries of 113 unaffected children. The spontaneous abortion rate in these cycles was as low as 17%, which confirms an almost five-fold reduction of spontaneous abortion rate following PGD for chromosomal rearrangements.

How to predict implantation? No correlation between embryonic aneuploidy and soluble human leukocyte antigen G-concentrations.

OBJECTIVE: To determine if soluble human leukocyte antigen-G (sHLA-G) concentrations in spent culture media may assist in identifying the normal embryo for implantation. DESIGN: Prospective blinded comparative study. SETTING: Reproductive genetic and reproductive medicine centers. PATIENT(S): One hundred and sixteen embryos obtained from eight patients undergoing in vitro fertilization (IVF) with preimplantation genetic diagnosis (PGD). INTERVENTION(S): Culture media obtained 2 days after fertilization were analyzed for sHLA-G concentrations using an enzyme-linked immunosorbent assay (ELISA) assay. A sHLA-G concentration of >or=1.9 mIU/mL was considered a positive predictor for successful implantation. Polar bodies and blastomeres from day-3 embryos were tested by PGD for 5 to 11 chromosomes: 8, 9, 13, 15, 16, 17, 18, 21, 22, X, and Y. MAIN OUTCOME MEASURE(S): The results of the sHLA-G concentrations were compared with the results of the PGD analyses. RESULT(S): We found an sHLA-G concentration >or=1.9 mIU/mL in 48% (56 out of 116) and normal PGD results in 52% (57 out of 116) of embryos. Of the embryos with normal PGD results, 46% (26 out of 57) had sHLA-G concentrations >or=1.9 mIU/mL. Among the embryos with sHLA-G >or=1.9 mIU/mL, 46% (26 out of 56) had normal PGD results, and 21% of embryos displayed both normal PGD results and sHLA-G >or=1.9 mIU/mL. CONCLUSION(S): No correlation between concentrations of sHLA-G in embryo culture media and PGD results of an embryo's aneuploidy were observed.

Correlation between preimplantation genetic diagnosis for chromosomal aneuploidies and the efficiency of establishing human ES cell lines.

There are several sources from which human embryonic stem cell (hESC) lines can be generated: surplus embryos after in vitro fertilization procedures, one- and three-pronuclear zygotes, early arrested or highly fragmented embryos that have reached the blastocyst stage, or otherwise chromosomally or genetically abnormal embryos after preimplantation genetic diagnosis (PGD). We report on the efficiency of establishing hESC lines from blastocysts with proven meiotic or mitotic errors after sequential testing of both polar bodies and blastomere analysis on day 3. The success rate of establishing hESC lines originating from blastocysts carrying a meiotic error was as low as 2.4% and differed significantly from the success rate of establishing hESC lines originating from blastocysts with balanced meiotic errors (21.6%) or mitotic errors (after sequential testing (9.1%) and after blastomere testing alone (12.2%)). This suggests that it may be reasonable to apply sequential PGD prior to the initiation of hESC culture. Information about the karyotype may in the future help refine the methods and possibly improve the efficiency by which hESC lines are derived from embryos with prezygotic abnormalities. Additionally, it may in general prove very difficult to obtain abnormal hESC lines for scientific study from aneuploid PGD embryos, which will limit our ability to study the biological consequences of chromosomal abnormalities. Furthermore, the success rates for generating aneuploid cell lines originating from fertilized oocytes carrying a prezygotic nondisjunction error seem to mirror the miscarriage rates during pregnancy of embryos carrying such errors.

Impact of meiotic and mitotic non-disjunction on generation of human embryonic stem cell lines.

At least 50-60% of oocytes derived from IVF procedures are chromosomally abnormal due to meiotic I or II errors. Through the use of polar body and blastomere diagnosis, euploid embryos suitable for transfer can be identified. Those embryos that are aneuploid are usually discarded, or otherwise can be used to generate chromosomally abnormal human embryonic stem cell (hESC) lines. The authors' centre has one of the largest repositories of hESC lines with genetic and chromosomal disorders generated from preimplantation genetic diagnosis (PGD) abnormal embryos. The results, studying hESC lines derived from PGD abnormal zygotes, imply that aneuploidies resulting from meiotic non-disjunction have a greater impact on viability of cells of the human embryos than those originating from post-zygotic mitotic non-disjunction.