Comprehensive preimplantation genetic testing for balanced insertional translocation carriers.

BACKGROUND: Balanced insertional translocations (BITs) can increase the risk of infertility, recurrent miscarriages or neonatal birth defects due to chromosomal imbalances in gametes. However, studies on preimplantation genetic testing (PGT) for patients carrying BITs are inadequate. METHODS: A preimplantation genetic genotyping and haplotype analysis approach was developed and implemented in this study. Genome-wide SNP genotyping was performed, followed by core family-based haplotype analysis. The balanced insertion segments in euploid embryos were inferred from the haplotypes inherited from the carrier parent. RESULTS: A total of 10 BIT carrier couples were enrolled in our study. 15 in vitro fertilisation cycles were conducted, resulting in 73 blastocysts biopsied and subjected to PGT analysis. Among these, 20 blastocysts displayed rearrangement-related imbalances, 13 exhibited de novo aneuploidies, 15 presented a complex anomaly involving both imbalances and additional aneuploidies, while 25 were euploid. Within the euploid embryos, 12 were balanced carrier embryos and 13 were non-carrier embryos. To date, eight non-carrier and one carrier embryos have been transferred, resulting in seven clinical pregnancies. All pregnancies were recommended to perform prenatal diagnosis, our date revealed complete concordance between fetal genetic testing results and PGT results. Presently, five infants have been born from these pregnancies, and two pregnancies are still ongoing. CONCLUSION: The proposed method facilitates comprehensive chromosome screening and the concurrent identification of balanced insertions or normal karyotypes in embryos. This study offers an effective and universally applicable strategy for BIT carriers to achieve a healthy pregnancy and prevent the transmission of BITs to their offspring.

Detection of cryptic balanced chromosomal rearrangements using high-resolution optical genome mapping.

BACKGROUND: Chromosomal rearrangements have profound consequences in diverse human genetic diseases. Currently, the detection of balanced chromosomal rearrangements (BCRs) mainly relies on routine cytogenetic G-banded karyotyping. However, cryptic BCRs are hard to detect by karyotyping, and the risk of miscarriage or delivering abnormal offspring with congenital malformations in carrier couples is significantly increased. In the present study, we aimed to investigate the potential of single-molecule optical genome mapping (OGM) in unravelling cryptic chromosomal rearrangements. METHODS: Eleven couples with normal karyotypes that had abortions/affected offspring with unbalanced rearrangements were enrolled. Ultra-high-molecular-weight DNA was isolated from peripheral blood cells and processed via OGM. The genome assembly was performed followed by variant calling and annotation. Meanwhile, multiple detection strategies, including FISH, long-range-PCR amplicon-based next-generation sequencing and Sanger sequencing were implemented to confirm the results obtained from OGM. RESULTS: High-resolution OGM successfully detected cryptic reciprocal translocation in all recruited couples, which was consistent with the results of FISH and sequencing. All high-confidence cryptic chromosomal translocations detected by OGM were confirmed by sequencing analysis of rearrangement breakpoints. Moreover, OGM revealed additional complex rearrangement events such as inverted aberrations, further refining potential genetic interpretation. CONCLUSION: To the best of our knowledge, this is the first study wherein OGM facilitate the rapid and robust detection of cryptic chromosomal reciprocal translocations in clinical practice. With the excellent performance, our findings suggest that OGM is well qualified as an accurate, comprehensive and first-line method for detecting cryptic BCRs in routine clinical testing.

Comprehensive chromosome FISH assessment of sperm aneuploidy in normozoospermic males.

PURPOSE: Sperm chromosomal abnormalities impact male fertility and pregnancy outcomes. However, the proportion of sperm with chromosomal abnormalities in normozoospermic men remains unclear. Herein, we evaluated sperm aneuploidy for 23 chromosomes to elucidate its incidence in normozoospermic men. METHODS: Sperm from ten normozoospermic donors were obtained from a human sperm bank and analyzed using fluorescence in situ hybridization. The frequencies of nullisomy, disomy, and diploidy were analyzed along with trisomy, triploidy, tetraploidy, and other numerical abnormalities per chromosome and per donor levels. RESULTS: A total of 248,811 sperm cells were analyzed (average: 24,881 ± 381 cells/donor), of which 246, 658 were haploid, 818 nullisomic, 393 disomic, 894 diploid, 13 triploid, 8 tetraploid, 3 trisomic, and 24 harbored multiple aneuploidies. Among the 22 autosomal and 2 sex chromosomes, the mean frequency of aneuploidy per chromosome was 0.49 ± 0.16%, including 0.33 ± 0.16% for nullisomy and 0.16 ± 0.08% for disomy. The mean frequencies of nullisomy, disomy, and aneuploidy per donor were 0.33 ± 0.13%, 0.16 ± 0.05%, and 0.49 ± 0.13%, respectively. The total frequencies of nullisomy, disomy, diploidy, and aneuploidy per donor were 7.62 ± 3.06%, 3.63 ± 1.12%, 0.36 ± 0.15%, and 11.25 ± 3.05%, respectively. CONCLUSIONS: The dominant chromosome numerical abnormalities in normozoospermic men are nullisomy, disomy, and diploidy. Generally, the frequency of nullisomy is higher than that of disomy. The disomy or nullisomy frequencies for each chromosome being gained or lost were not unified and varied; some chromosomes (e.g., chromosomes 21 and 22 and sex chromosomes) are more prone to disomy while some others (e.g., chromosome 3) are more prone to nullisomy.

Conventional ICSI improves the euploid embryo rate in male reciprocal translocation carriers.

PURPOSE: To evaluate whether the morphologically normal spermatozoa selected for intracytoplasmic sperm injection (ICSI) under microscope had a higher rate of normal/balanced chromosome contents than that in the whole unselected sperm from reciprocal translocation carriers. METHODS: Five hundred unselected spermatozoa from each of 40 male translocation carriers were performed with fluorescence in situ hybridization (FISH), to determine the rates of gametes with different meiotic contents of translocated chromosomes. Meanwhile, 3030 biopsied blastocysts from 239 male and 293 female reciprocal translocation carriers were detected with the microarray technique to analyze the rates of embryos with different translocated chromosome contents. RESULTS: The D3 embryo rate, blastocyst formation rate, and euploid rate of blastocysts were remarkably higher in male carriers than those in female (p = 0.001, p = 0.004, and p = 0.035, respectively). In addition, the percentages of alternate products, which contained normal/balanced chromosome contents, in embryos from male carriers were markedly higher than those in sperm FISH (p = 2.48 × 10-5 and p = 2.88 × 10-10), while the percentages of adjacent-2 and 3:1 products were lower than those in sperm FISH (p = 0.003 and p = 5.28 × 10-44). Moreover, consistent results were obtained when comparing the rates of products in embryos between male and female carriers. Specifically, the incidence of alternate products in male carriers was higher than those in female carriers (p = 0.022). However, no similar differences were seen between sperm and embryos of female carriers. CONCLUSION: ICSI facilitates the selection of spermatozoa with normal/balanced chromosome contents and improves the D3 embryo rate, blastocyst formation rate, and the euploid embryo rate in male carriers.

Analysis of segregation patterns of quadrivalent structures and the effect on genome stability during meiosis in reciprocal translocation carriers.

STUDY QUESTION: Do specific factors affect the segregation patterns of a quadrivalent structure and can the quadrivalent affect genome stability during meiosis? SUMMARY ANSWER: Meiotic segregation patterns can be affected by the carrier's gender and age, location of breakpoints and chromosome type, and the quadrivalent structure can increase genome instability during meiosis. WHAT IS KNOWN ALREADY: Carriers of reciprocal translocations have an increased genetic reproductive risk owing to the complex segregation patterns of a quadrivalent structure. However, the results of previous studies on the factors that affect segregation patterns seem to be contradictory, and the effect of a quadrivalent on genome stability during meiosis is unknown. STUDY DESIGN, SIZE, DURATION: We designed a retrospective study to analyze the segregation patterns of 24 chromosomes from reciprocal translocation and non-translocation patients. Data for 356 reciprocal translocation carriers and 53 patients with the risk to transmit monogenic inherited disorders (RTMIDs) undergoing PGD-single nucleotide polymorphism array analysis were collected. The study was performed between March 2014 and July 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS: Segregation patterns of a quadrivalent in 1842 blastocysts from 466 assisted reproduction cycles of reciprocal translocation carriers were analyzed according to the location of chromosome breakpoints, the carrier's gender and age, and chromosome type. In addition, to analyze the effect of quadrivalent structure on genome stability, segregation products of chromosomes which are not involved in the translocation from translocation carriers were compared with those of 23 pairs of chromosomes in 318 blastocysts from 72 assisted reproduction cycles of patients with RTMIDs. MAIN RESULTS AND THE ROLE OF CHANCE: The percentage of adjacent-2 products with severe asymmetric quadrivalent was significantly higher than those with mild asymmetric quadrivalent (P = 0.020) while, in contrast, the incidence of 4:0/others was lower (P = 0.030). The frequencies of adjacent-1, adjacent-2 and 3:1 products differed between male and female carriers (P < 0.001, P = 0.015 and P = 0.001, respectively), and also for adjacent-1 and 4:0/others products in young versus older carriers (P = 0.04 and P = 0.002, respectively). In addition, adjacent-1 products of a quadrivalent with an acrocentric chromosome were significantly higher than those of a quadrivalent without an acrocentric chromosome (P = 0.001). Moreover, a quadrivalent could significantly increase the frequencies of abnormal chromosomes compared to patients with RTMIDs (P = 0.048, odds ratio (OR) = 1.43, 95% CI = 1.01-2.43), especially for the male carriers (P = 0.018, OR = 1.58, 95% CI = 1.08-2.25). In contrast, for older carriers, no difference was found in both aneuploidy and segmental anomalies compared to patients with RTMIDs. LIMITATIONS, REASONS FOR CAUTION: The study contained appropriate controls, yet the analysis was limited by a small number of control patients and embryos. WIDER IMPLICATIONS OF THE FINDINGS: Until now, there had been no definite report about the effect of quadrivalents on genome stability in reciprocal translocation carriers compared with control samples, and in the present study the large sample size ensured a detailed analysis of factors with a possible impact on segregation patterns. These data provide a better insight into the meiotic mechanisms involved in non-disjunction events in gametes from reciprocal translocation carriers. In addition, our results will help to provide each reciprocal translocation carrier couple undergoing PGD with more appropriate genetic counseling and a better understanding of the large numbers of abnormal embryos with chromosome aneuploidy. STUDY FUNDING/COMPETING INTEREST(S): The research was supported by the Research Funding of Shanghai Ji Ai Genetics & IVF Institute and the authors declare a lack of competing interests in this study.

[Prenatal diagnosis of two cases of paternal uniparental disomy of chromosome 6].

OBJECTIVE: To report on prenatal diagnosis and follow up of two patients with paternal uniparental disomy of chromosome 6 (pUPD6). METHODS: Fetal cells were subjected to in situ culturing and G-banded chromosomal analysis. DNA samples of the fetuses and their parents were also analyzed with single nucleotide polymorphism microarray (SNP array). RESULTS: Both fetuses had a normal male karyotype. SNP array analysis showed both have carried pUPD6. CONCLUSION: pUPD6 can lead to transient neonatal diabetes mellitus type 1. Homozygous status of recessive mutations, disorder of gene imprinting, and its influence on placental function are the main factors to be considered during prenatal diagnosis and genetic counseling for pUPD6.

Quadrivalent asymmetry in reciprocal translocation carriers predicts meiotic segregation patterns in cleavage stage embryos.

The effect of quadrivalent geometry on meiotic behaviour was evaluated. Segregation patterns of 404 cleavage stage embryos from 40 reciprocal translocation carriers undergoing 75 PGD cycles were analysed according to the asymmetric degree of quadrivalent. The percentage of alternate products with severe asymmetric quadrivalents was significantly lower than patients with mild asymmetric quadrivalents (22.5% versus 38.7%, P = 0.001). The incidence of 3:1 products was significantly higher in patients with severe compared with mild asymmetric quadrivalents (23.1% versus 12.2%, P = 0.004). The incidence of adjacent 1 (25.8% versus 24.3%), 2 (11.5% versus 12.6%) and 4:0/other segregation products (17.0% versus 12.2%) were not statistically significantly different between embryos from patients with severe or mild asymmetric quadrivalents. After adjusting for the confounder of sex using a logistic regression model, the odds of alternate embryos is about one-half for carriers classified as severe (OR 0.456, 95% CI 0.291 to 0.705), and the odds of 3:1 embryos is 2.2 times higher for carriers with severe asymmetric quadrivalents (OR 2.235, 95% CI 1.318 to 3.846). Our results suggest that the meiotic segregation pattern is related to the degree of asymmetry of specific quadrivalents. Severe asymmetric quadrivalents increases the risk of abnormal embryos.

[Efficiency of multi-round fluorescence in situ hybridization and its influencing factors in preimplantation genetic diagnosis].

OBJECTIVE: To investigate the efficiency of multi-round fluorescence in situ hybridization (FISH) and its influencing factors in preimplantation genetic diagnosis (PGD). METHODS: A total of 48 couples accepted PGD because of various reasons: 24 with Robertsonian translocations, 16 with reciprocal translocations, 2 with pericentric inversions, one with advanced maternal age who had a previous liveborn of Down syndrome, 3 suffered from sex chromosome abnormalities and 2 repeated spontaneous miscarriages. After 72 retrieval cycles, 432 cleavage stage embryos with more than six cells were biopsied on day three. Only intact nuclei (396) were hybridized in order to verify the chromosomal status of the individual embryos. If previous FISH has failed to give conclusive results while the nuclei remained undamaged, the nuclei were hybridized once again. A total of 870 times of hybridization were conducted to 396 nuclei. Signal identification rates of each round as well as the influence of different probes to the hybridization efficiency were compared. Factors leading to inconclusive FISH results were analyzed as well. RESULTS: Five hundred and thirty five out of 870 hybridizations gave identifiable signals (61.5%). The second and third round FISH showed the best signals with an identification rate of 71.8% and 77.4%, respectively, which were significantly higher than those of the first round (52.8%, P < 0.01), the fourth round (55.8%, P < 0.05, P < 0.01), the fifth round (54.5%, P < 0.05) and the sixth round (27.3%, P < 0.01). The identification rate of centromere specific probe signals (CEP group) was 80.3% and the former three rounds in this group got the best quality of signals with an identification rate of 85.7%, 85.1% and 88.0%, respectively, which was significantly higher than that of the latter three rounds. The identification rate of other probe was much lower than with the CEP probe (55.2% vs. 80.3%, P < 0.01) and the best quality of signal in this group was achieved in the fifth round (72.7%), followed by the second round (66.1%) and the third round (63.8%). The identification rate of the first round (50.3%) and the sixth round (22.2%) were significantly lower compared with the second round (P < 0.01). During the 6 rounds of FISH, 335 hybridizations did not give conclusion results (38.5%, 335/870). The main cause of unidentification was weak signals (20.9%, 182/870). Other common factors included background interference (7.6%, 66/870) and failed hybridization (6.1%, 53/870). Rare causes included nucleus damage (1.8%, 16/870), nucleus loss (1.1%, 10/870) and signal split/overlap (0.9%, 8/870). CONCLUSION: Multi-round FISH can improve the utility of single nucleus in PGD and the former three rounds have the highest efficiency. The hybridization effect of CEP is better than other probe. Poor signal quality is the common cause of unidentification results.

A Novel System for the Detection of Spontaneous Abortion-Causing Aneuploidy and Its Erroneous Chromosome Origins through the Combination of Low-Pass Copy Number Variation Sequencing and NGS-Based STR Tests.

During the period of 2018-2020, we first combined reported low-pass whole genome sequencing and NGS-based STR tests for miscarriage samples analysis. Compared with G-banding karyotyping, the system increased the detection rate of chromosomal abnormalities in miscarriage samples to 56.4% in 500 unexplained recurrent spontaneous abortions. In this study, a total of 386 STR loci were developed on twenty-two autosomes and two sex chromosomes (X and Y chromosomes), which can help to distinguish triploidy, uniparental diploidy and maternal cell contamination and can trace the parental origin of erroneous chromosomes. It is not possible to accomplish this with existing methods of detection in miscarriage samples. Among the tested aneuploid errors, the most frequently detected error was trisomy (33.4% in total and 59.9% in the error chromosome group). In the trisomy samples, 94.7% extra chromosomes were of maternal origin and 5.31% were of paternal origin. This novel system improves the genetic analysis method of miscarriage samples and provides more reference information for clinical pregnancy guidance.

Combined Preimplantation Genetic Testing for Genetic Kidney Disease: Genetic Risk Identification, Assisted Reproductive Cycle, and Pregnancy Outcome Analysis.

Background: Genetic kidney disease is a major cause of morbidity and mortality in neonates and end-stage renal disease (ESRD) in children and adolescents. Genetic diagnosis provides key information for early identification of congenital kidney disease and reproductive risk counseling. Preimplantation genetic testing for monogenic disease (PGT-M) as a reproductive technology helps prospective parents to prevent passing on disease-causing mutations to their offspring. Materials and Methods: A retrospective cohort of couples counseled on PGT who had a risk to given birth to a child with genetic kidney disease or had a history of prenatal fetal kidney and urinary system development abnormalities from 2011 to 2021. Through a combination of simultaneously screening for aneuploidy and monogenic kidney disease, we achieved reproductive genetic intervention. Results: A total of 64 couples counseled on PGT for monogenic kidney disease in a single reproductive center during the past 10 years, of whom 38 different genetic kidney diseases were identified. The most frequent indications for referral were autosomal recessive disease (54.7%), then autosomal dominant disease (29.7%), and X-linked disease (15.6%). Polycystic kidney disease was the most common diseases counted for 34.4%. After oocyte-retrieval in all of 64 females, a total of 339 embryos were diagnosed and 63 embryos were transferred in succession. Among 61 cycles of frozen-embryo transfer (FET), ongoing pregnancy/live birth rate (OP/LBR) reached 57.38%. The cumulative OP/LBR in our cohort for the 64 couples was 54.69%. In addition, we have carried out expanded carrier screening (ECS) in all the in vitro fertilization (IVF) couples performed PGT covering 7,311 individuals. The carrier frequency of the candidate genes for monogenic kidney diseases accounted for 12.19%. Conclusion: Overall, the customization PGT-M plan in our IVF center is pivotal to decreasing the morbidity and implementing reproductive genetic intervention of genetic kidney disease.

FISH analysis of numerical chromosomal abnormalities in the sperm of robertsonian translocation der(13; 14)(q10;q10) carriers.

Fluorescence in situ hybridization analysis of numerical chromosomal abnormalities in the sperm of Robertsonian translocation der (13;14) (q10;q10) carriers has focused on a limited number of chromosomes mainly on chromosome 13, 18, 21, X, and Y. Here, we aimed to expand the analysis to all chromosomes by increasing the number of probes analyzed in fluorescence in situ hybridization. The incidence of numerical abnormalities of all chromosomes (1-22, X, and Y) was determined in sperm from 10 carriers of the Robertsonian translocation der(13;14)(q10;q10) and 10 normozoospermic males to fully assess the effect of translocation-derived chromosome on the segregation of all chromosomes during meiosis. Numerical abnormalities of the two translocated chromosomes were frequently detected in the sperm of der (13;14) translocation carriers, with an average frequency of 14.55% ± 6.00% for chromosome 13 and 13.27% ± 4.14% for chromosome 14. Numerical abnormalities of nontranslocated chromosomes, with an average frequency of 1.77% ± 0.62% (range, 1.16%-3.73%), was lower than that of translocated chromosome. However, the cumulative numerical abnormality of the 22 nontranslocated chromosomes was comparable to that of the two translocated chromosomes. Significantly increased numerical abnormalities in der(13;14) translocation carriers compared with those in normozoospermic males indicates the presence of translocation-derived chromosome disturbances, with translocated chromosomes being most affected; nontranslocated chromosomes were also affected, but to a lesser extent due to a mild interchromosomal effect.

A comprehensive and universal approach for embryo testing in patients with different genetic disorders.

BACKGROUND: In vitro fertilization (IVF) with preimplantation genetic testing (PGT) has markedly improved clinical pregnancy outcomes for carriers of gene mutations or chromosomal structural rearrangements by the selection of embryos free of disease-causing genes and chromosome abnormalities. However, for detecting whole or segmental chromosome aneuploidies, gene variants or balanced chromosome rearrangements in the same embryo require separate procedures, and none of the existing detection platforms is universal for all patients with different genetic disorders. METHODS: Here, we report a cost-effective, family-based haplotype phasing approach that can simultaneously evaluate multiple genetic variants, including monogenic disorders, aneuploidy, and balanced chromosome rearrangements in the same embryo with a single test. A total of 12 monogenic diseases carrier couples and either of them carried chromosomal rearrangements were enrolled simultaneously in this present study. Genome-wide genotyping was performed with single-nucleotide polymorphism (SNP)-array, and aneuploidies were analyzed through SNP allele frequency and Log R ratio. Parental haplotypes were phased by an available genotype from a close relative, and the embryonic genome-wide haplotypes were determined through family haplotype linkage analysis (FHLA). Disease-causing genes and chromosomal rearrangements were detected by haplotypes located within the 2 Mb region covering the targeted genes or breakpoint regions. RESULTS: Twelve blastocysts were thawed, and then transferred into the uterus of female patients. Nine pregnancies had reached the second trimester and five healthy babies have been born. Fetus validation results, performed with the amniotic fluid or umbilical cord blood samples, were consistent with those at the blastocyst stage diagnosed by PGT. CONCLUSIONS: We demonstrate that SNP-based FHLA enables the accurate genetic detection of a wide spectrum of monogenic diseases and chromosome abnormalities in embryos, preventing the transfer of parental genetic abnormalities to the fetus. This method can be implemented as a universal platform for embryo testing in patients with different genetic disorders.

Meiotic Heterogeneity of Trivalent Structure and Interchromosomal Effect in Blastocysts With Robertsonian Translocations.

BACKGROUND: Robertsonian translocations are common structural rearrangements and confer an increased genetic reproductive risk due to the formation of trivalent structure during meiosis. Studies on trivalent structure show meiotic heterogeneity between different translocation carriers, although the factors causing heterogeneity have not been well elaborated in blastocysts. It is also not yet known whether interchromosomal effect (ICE) phenomenon occurs in comparison with suitable non-translocation control patients. Herein, we aimed to evaluate the factors that cause meiotic heterogeneity of trivalent structure and the ICE phenomenon. METHODS: We designed a retrospective study, comprising 217 Robertsonian translocation carriers and 134 patients with the risk of transmitting monogenic inherited disorders (RTMIDs) that underwent preimplantation genetic testing (PGT). Data was collected between March 2014 and December 2019. The segregation products of trivalent structure were analyzed based on the carrier's gender, age and translocation type. In addition, to analyze ICE phenomenon, aneuploidy abnormalities of non-translocation chromosomes from Robertsonian translocation carriers were compared with those from patients with RTMIDs. RESULTS: We found that the percentage of male carriers with alternate segregation pattern was significantly higher [P < 0.001, odds ratio (OR) = 2.95] than that in female carriers, while the percentage of adjacent segregation pattern was lower (P < 0.001, OR = 0.33). By contrast, no difference was observed between young and older carriers when performing stratified analysis by age. Furthermore, segregation pattern was associated with the D;G chromosomes involved in Robertsonian translocation: the rate of alternate segregation pattern in Rob(13;14) carriers was significantly higher (P = 0.010, OR = 1.74) than that in Rob(14;21) carriers, whereas the rate of adjacent segregation pattern was lower (P = 0.032, OR = 0.63). Moreover, the results revealed that the trivalent structure could significantly increase the frequencies of chromosome aneuploidies 1.30 times in Robertsonian translocation carriers compared with patients with RTMIDs (P = 0.026), especially for the male and young subgroups (P = 0.030, OR = 1.35 and P = 0.012, OR = 1.40), while the mosaic aneuploidy abnormalities presented no statistical difference. CONCLUSIONS: Our study demonstrated that meiotic segregation heterogeneity of trivalent structure is associated with the carrier's gender and translocation type, and it is independent of carrier's age. ICE phenomenon exists during meiosis and then increases the frequencies of additional chromosome abnormalities.

Next-Generation Sequencing Is More Efficient at Detecting Mosaic Embryos and Improving Pregnancy Outcomes than Single-Nucleotide Polymorphism Array Analysis.

We compared chromosomal mosaicism, detected by next-generation sequencing (NGS), during preimplantation genetic testing (PGT) with that detected by single-nucleotide polymorphism (SNP) array-based PGT to assess the pregnancy outcomes associated with both platforms in a retrospective cohort study of patients undergoing in vitro fertilization in a single university-based assisted reproduction center. In total, 6427 blastocysts biopsied from 1513 patients who underwent 2833 oocyte retrievals from January 2017 to February 2019 were identified. The incidence of mosaicism was significantly higher in the NGS-based PGT group than in the SNP array-based PGT group. Furthermore, some aneuploid specimens were affected by mosaicism. The total mosaicism detection rate with NGS-based PGT (23.3%) was significantly higher than that with SNP array-based PGT (7.7%). Mosaicism rates were similar when stratified by maternal age or PGT type. The SNP array cohort showed a significantly higher spontaneous abortion rate than the NGS cohort (10.07% versus 6.33%; P = 0.0403). The ongoing pregnancy/live birth rate was higher in the NGS cohort (44.1%) than in the SNP array cohort (42.28%). Our results confirm that NGS-based PGT can detect mosaicism more frequently than SNP array-based PGT in trophectoderm specimens. Therefore, clinical application of NGS for PGT may improve pregnancy outcomes compared with that of SNP array-based PGT. More detailed blastocyst detection and classification is necessary to prioritize embryo transfers.

Combined 677CC/1298AC genotypes of methylenetetrahydrofolate reductase (MTHFR ) reduce susceptibility to precursor B lymphoblastic leukemia in a Chinese population.

The methylenetetrahydrofolate reductase (MTHFR) encodes a major enzyme in folate metabolism. It has been suggested that two MTHFR polymorphisms, 677C>T and 1298A>C, influence risk of acute lymphoblastic leukemia (ALL). Most studies on relation of MTHFR polymorphisms to ALL susceptibility have been in pediatric populations because ALL is relatively rare in adults. Here, we report a case-control study of 127 Chinese patients with adult precursor B lymphoblastic leukemia (B-ALL) to examine correlation between the MTHFR polymorphisms and B-ALL susceptibility in adults. Our data show that although the prevalence of genotype 1298CC was significantly higher in the female patients than in the controls (P = 0.04), the differences in distributions of combined genotypes of 1298CC with either 677CC or 677CT between the cases and the controls were statistically insignificant. Haplotype analysis revealed no significant difference between the cases and the controls. The prevalence for joint MTHFR genotypes 677CC/1298AC was significantly lower in the female B-ALL cases than in the controls [odds ratio (OR) = 0.06, 95% CI = 0.00-0.53, P = 0.0033] and no differences among the men [OR = 0.71, 95% CI = 0.20-2.53, P = 0.55], suggesting that protective effects of combined MTHFR 677CC/1298AC genotypes on susceptibility of adult B-ALL are gender bias toward women with 677CC/1298AC women being at a 17-fold reduced odds to develop B-ALL.

Adult precursor B lymphoblastic leukemia in Shanghai, China: characterization of phenotype, cytogenetics and outcome for 137 consecutive cases.

Acute lymphoblastic leukemia (ALL) accounts for 20-30% of adult leukemia in the West. However, detailed studies of B-cell-specific ALL in adult Asian populations are lacking. We diagnosed and characterized 137 consecutive cases of precursor B lymphoblastic leukemia (precursor B-cell ALL) presented to our laboratory in Shanghai using the WHO 2001 classification system. Patient clinical, phenotypic and cytogenetic characteristics were correlated with outcome. In contrast to Western studies, females (71) outnumbered males (66) partly due to an increased prevalence of the CD10- pro B-cell phenotype. Females with a CD10- pro B-cell phenotype exhibited significantly better overall survival than males. The most common cytogenetic abnormality was the Philadelphia chromosome (PH/BCR/ABL) which was found in approximately 37% of the cases. Cases of precursor B cell ALL lacking the PH/BCR/ABL genotype exhibited a pronounced age-dependent, gender prevalence with a modal age in the sixth decade for females compared to the second decade for males. These findings suggest significant geographic heterogeneity in precursor B-cell ALL which may be of both etiological and therapeutic significance.