Preimplantation genetic testing for complex chromosomal rearrangement carriers by next-generation sequencing

Case report: Optical genome mapping revealed double rearrangements in a male undergoing preimplantation genetic testing

Chromosome rearrangement is one of the main causes of abortion. In individuals with double chromosomal rearrangements, the abortion rate and the risk of producing abnormal chromosomal embryos are increased. In our study, preimplantation genetic testing for structural rearrangement (PGT-SR) was performed for a couple because of recurrent abortion and the karyotype of the male was 45, XY der (14; 15)(q10; q10). The PGT-SR result of the embryo in this in vitro fertilization (IVF) cycle showed microduplication and microdeletion at the terminals of chromosomes 3 and 11, respectively. Therefore, we speculated whether the couple might have a cryptic reciprocal translocation which was not detected by karyotyping. Then, optical genome mapping (OGM) was performed for this couple, and cryptic balanced chromosomal rearrangements were detected in the male. The OGM data were consistent with our hypothesis according to previous PGT results. Subsequently, this result was verified by fluorescence in situ hybridization (FISH) in metaphase. In conclusion, the male’s karyotype was 45, XY, t(3; 11)(q28; p15.4), der(14; 15)(q10; q10). Compared with traditional karyotyping, chromosomal microarray, CNV-seq and FISH, OGM has significant advantages in detecting cryptic and balanced chromosomal rearrangements.

Analysis of complex chromosomal rearrangements using a combination of current molecular cytogenetic techniques

BACKGROUND

Using combined fluorescence in situ hybridization (FISH) and high-throughput whole-genome sequencing (WGS) molecular cytogenetic technology, we aim to analyze the junction breakpoints of complex chromosome rearrangements (CCR) that were difficult to identify by conventional karyotyping analysis and further characterize the genetic causes of recurrent spontaneous abortion.

RESULTS

By leveraging a combination of current molecular techniques, including chromosome karyotype analysis, FISH, and WGS, we comprehensively characterized the extremely complex chromosomal abnormalities in this patient with recurrent spontaneous abortions. Here, we demonstrated that combining these current established molecular techniques is an effective and efficient workflow to identify the structural abnormalities of complex chromosomes and locate the rearrangement of DNA fragments.

CONCLUSIONS

In conclusion, leveraging results from multiple molecular and cytogenetic techniques can provide the most comprehensive genetic analysis for genetic etiology research, diagnosis, and genetic counseling for patients with recurrent spontaneous abortion and embryonic abortion.

In vitro fertilization outcomes after preimplantation genetic testing for chromosomal structural rearrangements comparing fluorescence in-situ hybridization, microarray comparative genomic hybridization, and next-generation sequencing

Objective

To compare in vitro fertilization (IVF) outcomes for preimplantation genetic testing for chromosomal structural rearrangements (PGT-SR) using various testing platforms.

Design

Retrospective cohort.

Setting

Large academic IVF center.

Patient(s)

Fifty-one balanced translocation carriers undergoing IVF with PGT-SR who completed a total of 91 cycles, including 31 fluorescence in-situ hybridization (FISH), 24 microarray comparative genomic hybridization (aCGH), and 36 next-generation sequencing (NGS) testing cycles.

Intervention(s)

PGT-SR.

Main Outcome Measure(s)

Primary outcome of live-birth rate and secondary outcomes including implantation rate, clinical loss rate, and percentages of normal or balanced, unbalanced, and aneuploid embryos detected.

Result(s)

There was no statistically significant difference in LBR, though there was a tendency toward a higher LBR for NGS testing (14 of 19, 73.7%) compared with FISH (8 of 18, 44.4%) and aCGH (10 of 20, 50.0%). The implantation rate was statistically significantly higher for NGS (16 of 20, 80.0%) compared with FISH (11 of 25, 44.0%) and aCGH (16 of 30, 53.3%). There was no statistically significant difference in clinical pregnancy losses. There was a lower percentage of normal or balanced embryos with FISH (12.5%) compared with aCGH (23.7%) and with NGS (20.7%).

Conclusion(s)

This is the first report of PGT-SR outcomes for translocation carriers directly comparing PGT-SR using FISH, aCGH, and NGS. Our findings suggest an improvement in pregnancy outcomes parallel to the advancement in technology and are reassuring for continued use of NGS for this population.

Coenzyme Q10 supplementation of human oocyte in vitro maturation reduces postmeiotic aneuploidies

OBJECTIVE

To evaluate the effect of coenzyme Q10 (CoQ10) supplementation on oocyte maturation rates and postmeiotic aneuploidy rates during in vitro maturation (IVM) of human oocytes.

DESIGN

Clinical laboratory observation.

SETTING

Hospital and university laboratories.

PATIENT(S)

Forty-five patients aged ≥38 years and 18 patients aged ≤30 years undergoing in vitro fertilization.

INTERVENTION(S)

The germinal vesicle-stage oocytes and associated cumulus cells were cultured in IVM media for 24-48 hours with or without 50 μmol/L CoQ10. Oocyte maturation rates were determined based on the presence or absence of the first polar body. Postmeiotic aneuploidies were determined using next-generation sequencing analyses of biopsied polar bodies.

MAIN OUTCOME MEASURE(S)

Oocyte maturation rates, postmeiotic oocyte aneuploidy rates, and chromosome aneuploidy frequencies.

RESULT(S)

In women aged 38-46 years, 50 μmol/L CoQ10 significantly increased oocyte maturation rates (82.6% vs. 63.0%; P=.035), reduced oocyte aneuploidy rates (36.8% vs. 65.5%; P=.020), and reduced chromosome aneuploidy frequencies (4.1% vs. 7.0%; P=.012. In women aged ≤30 years, we failed to demonstrate an effect of CoQ10 on oocyte maturation rates or postmeiotic aneuploidies.

CONCLUSION(S)

CoQ10 supplementation during IVM increased oocyte maturation rates and reduced postmeiotic aneuploidies for older women.

The influence of balanced complex chromosomal rearrangements on preimplantation embryonic development potential and molecular karyotype

BACKGROUND

Balanced complex chromosome rearrangements (BCCR) are balanced chromosomal structural aberrations that involve two or more chromosomes and at least three breakpoints. It is very rare in the population. The objective is to explore the difference of influence of three types of BCCR on early embryonic development and molecular karyotype.

RESULTS

Twelve couples were recruited including four couples of three-way rearrangements carriers (group A), three couples of double two-way translocations carriers (group B) and five couples of exceptional CCR carriers (group C). A total of 243 oocytes were retrievedin the seventeen preimplantation genetic testing (PGT) cycles, and 207 of these were available for fertilization. After intracytoplasmic sperm injection, 181oocytes normally fertilized. The rates of embryos forming on day3 in three groups were 87.88, 97.78 and77.14%, which was significantly different (P = 0.01). Compared with group B, the rate of embryo formation was statistically significantly lower in group C (P = 0.01). Furthermore, the rates of high-quality blastocysts in three group were 14.71, 48.15 and 62.96%, respectively, which was significantly different (P = 0.00). Compared with group B andC, the rate of high-quality blastocysts in group A was statistically significantly lower (P = 0.00;P = 0.00). Comprehensive chromosome analysis was performed on 83 embryos, including 75 trophectodermcellsand 8 blastomeres. Except 7 embryos failed to amplify, 9.01%embryos were diagnosed as euploidy, and 90.91% were diagnosed as abnormal. As for group A, the euploid embryo rate was 10.71%and the abnormal embryo rate was 89.29%. In group B,the euploid embryo rate was 3.85%, the abnormal embryo rate was 96.15%. The euploid embryo rate was 13.04%, the abnormal embryo rate was 86.96% in group C. There were no significant differences among the three groups (P = 0.55).

CONCLUSIONS

The lowest rate of high quality blastocysts has been for three-way rearrangements and the lowest rate of euploidy has been for double two-way translocations, although no significant difference. Different types of BCCR maybe have little effect on the embryonic molecular karyotype. The difference of influence of BCCR on early embryonic developmentandmolecular karyotypeshould be further studied.