Karyomapping in preimplantation genetic testing for β-thalassemia combined with HLA matching: a systematic summary

Reproductive Choices in Haemoglobinopathies: The Role of Preimplantation Genetic Testing

Haemoglobinopathies are among the most prevalent genetic disorders globally. In the context of these conditions, preimplantation genetic testing (PGT) plays a pivotal role in preventing genetic diseases in the offspring of carrier parents, reducing the need for pregnancy termination and enabling the selection of compatible sibling donors for potential stem cell transplantation in cases of thalassemia or sickle cell disease. This review explores the evolving role of PGT as a reproductive option for haemoglobinopathy carriers, tracing the development of PGT protocols from patient-specific to comprehensive testing enabled by advanced technologies like next-generation sequencing (NGS). We discuss key technical, biological, and practical limitations of PGT, as well as the ethical considerations specific to haemoglobinopathies, such as the complexity of interpreting genotypes. Emerging technologies, such as whole-genome sequencing, non-invasive PGT, and gene editing, hold significant promise for expanding applications but also raise new challenges that must be addressed. It will be interesting to explore how advancements in technology, along with the changing management of haemoglobinopathies, will impact reproductive choices. It is anticipated that continued research will improve genetic counseling for PGT for haemoglobinopathies, while a careful evaluation of ethical and societal implications is also required. Responsible and equitable implementation of PGT is essential for ensuring that all families at risk can make informed reproductive choices.

Knowledge, attitude and acceptance regarding bone marrow transplantation in caregivers of beta-thalassemia major patients

OBJECTIVE

Knowledge, Attitude, and Acceptance regarding Bone marrow transplantation in caregivers of beta-thalassemia major patients.

METHODS

A cross-sectional study was conducted among the caregivers of pediatric patients with betathalassemia major in blood transfusion centres in Bangalore, India. Their knowledge, attitude, and acceptance regarding bone marrow transplantation were assessed using a validated questionnaire. The study aimed to identify factors that influence caregivers' decision about bone marrow transplantation.

RESULTS

The knowledge, attitude, and acceptance of the caregivers towards bone marrow transplantation are shown to depend on gender, education and socio-economic status. The results of this study reveal that male caregivers generally exhibited higher levels of knowledge and had a better attitude towards it as compared to their female counterparts. Higher education and socio-economic status were associated with better knowledge, more favourable attitudes and a higher acceptance towards the procedure.

Differences in preimplantation blastocyst chromosomal aberrations between polycystic ovary syndrome women and controls: a multi-center retrospective cohort study

PURPOSE

Comprehensive chromosomal status of blastocyst from women with polycystic ovary syndrome (PCOS) was limited. This study aimed to identify possible differences in the preimplantation blastocyst chromosome aberrations between PCOS women and controls receiving preimplantation genetic testing (PGT).

METHODS

This was a multi-center retrospective cohort study including a total of 707 blastocysts from 147 PCOS women and 3006 blastocysts from 821 control women receiving PGT between 2015 and 2021. Embryonic chromosomal aberration spectrums were compared between PCOS and controls. Mixed effects generalized linear model was conducted to explore possible influence of PCOS-related endocrinological disorders on embryonic chromosomal abnormalities.

RESULTS

Blastocysts from PCOS demonstrated significantly lower aneuploidy rate (15.2% vs. 25.2% per women, P < 0.001; 14.7% vs. 25.4% per blastocyst, P < 0.001) but greater mosaicism rate (12.5% vs. 8.0% per women, P = 0.007; 16.5% vs. 8.7% per blastocyst, P < 0.001). Mixed effects generalized linear model identified PCOS as an independent protective factor against embryonic aneuploidy (adjusted odds ratio = 0.68, 95% confidence interval, 0.50-0.93, P = 0.014) but a risk factor for embryonic mosaicism (adjusted odds ratio = 1.52, 95% confidence interval 1.11-2.10, P = 0.009). Further model analysis suggested that insulin resistance could be responsible for the increased risk of embryonic mosaicism among PCOS women (adjusted odds ratio = 2.17, 95% confidence interval, 1.10-4.31, P = 0.026).

CONCLUSION

PCOS is associated with a lower aneuploidy risk but an increased mosaicism risk in preimplantation blastocysts, and insulin resistance should be investigated as a potential cause.

An Incidental Detection of a Rare UPD in SNP-Array Based PGT-SR: A Case Report

Uniparental disomies (UPD) refers to the inheritance of both homologs of a chromosome from only one parent with no representative copy from the other parent. UPD was with an estimated prevalence of 0.15‰ in population. Current understanding of UPD was limited to subjects for which UPD was associated with clinical manifestation due to imprinting disorders or recessive diseases. Segmental UPD was rare, especially for a segmental UPD with a combination of hetero- and isodisomy. This paper presents a couple with reciprocal translocation 46,XY, t(14;22)(q32.3;q12.2) for PGT-SR. Among 8 biopsied blastocysts, one euploid blastocyst (No.4) with segmental loss of heterozygosity (LOH)(22) [arr[hg19] q12.1q22.3 (28,160,407 - 35,407,682)] was detected by B allele frequency. We found the chromosome contained both UPiD(22) [arr[hg19] q12.1q22.3 (28,160,407 - 35,407,682) ×2 hmz mat] and UPhD(22) [arr[hg19] q22.3qter(35,407,682 - 51,169,045) ×2 htz mat] by haplotype analysis. UPDtool software confirmed the result. What's more, the segmental UPD and reciprocal translocation shared the same breakpoint, chr22q12.1 (28,160,407), while the breakpoint between iso- and heterodisomy was chr22q22.3 (35,407,682). We reported the first segmental UPD with a combination of hetero- and isodisomy, which may result from aneuploidy rescue. This case emphasizes the importance of the combination of comprehensive chromosome screening and haplotype analysis to reduce the risk of misdiagnosis.

Appropriate whole genome amplification and pathogenic loci detection can improve the accuracy of preimplantation genetic diagnosis for deletional α-thalassemia

Objective

To improve the accuracy of preimplantation genetic testing (PGT) in deletional α-thalassemia patients.

Design

Article.

Patients

fifty-two deletional α-thalassemia couples.

Interventions

Whole genome amplification (WGA), Next-generation sequencing (NGS) and PCR mutation loci detection.

Main outcome measures

WGA, Single nucleotide polymorphism (SNP) and PCR mutation loci detection results; Analysis of embryo chromosome copy number variation (CNV).

Results

Multiple Displacement Amplification (MDA) and Multiple Annealing and Looping-Based Amplification Cycles (MALBAC) methods for PGT for deletional α-thalassemia. Blastocyst biopsy samples (n = 253) were obtained from 52 deletional α-thalassemia couples. The results of the comparison of experimental data between groups MALBAC and MDA are as follows: (i) The average allele drop-out (ADO) rate, MALBAC vs. MDA = 2.27% ± 3.57% vs. 0.97% ± 1.4%, P=0.451); (ii) WGA success rate, MALBAC vs. MDA = 98.61% vs. 98.89%, P=0.851; (iii) SNP haplotype success rate, MALBAC vs. MDA = 94.44% vs. 96.68%, P=0.409; (iv) The result of SNP haplotype analysis is consistent with that of Gap-PCR/Sanger sequencing results, MALBAC vs. MDA = 36(36/72, 50%) vs. 151(151/181, 83.43%), P=0; (v) Valid SNP loci, MALBAC vs. MDA = 30 ± 9 vs. 34 ± 10, P=0.02; (vi) The mean CV values, MALBAC vs. MDA = 0.12 ± 0.263 vs. 0.09 ± 0.40, P=0.916; (vii) The average number of raw reads, MALBAC vs. MDA =3244259 ± 999124 vs. 3713146 ± 1028721, P=0; (viii) The coverage of genome (%), MALBAC vs. MDA = 5.02 ± 1.09 vs. 5.55 ± 1.49, P=0.008.

Conclusions

Our findings indicate that MDA is superior to MALBAC for PGT of deletional α-thalassemia. Furthermore, SNP haplotype analysis combined with PCR loci detection can improve the accuracy and detection rate of deletional α-thalassemia.

Preimplantation genetic testing for X-linked chronic granulomatous disease induced by a CYBB gene variant: A case report

INTRODUCTION

X-linked recessive chronic granulomatous disease (XR-CGD) is a severe primary immunodeficiency principally caused by a CYBB (OMIM: 300481) gene variant. Recurrent fatal bacterial or fungal infections are the main clinical manifestations of XR-CGD.

PATIENT CONCERNS

In the current case, in vitro fertilization (IVF) associated with preimplantation genetic testing for monogenic disorder (PGT-M) was applied for a Chinese couple who had given birth to a boy with XR-CGD.

DIAGNOSIS

Next-generation sequencing-based SNP haplotyping and Sanger-sequencing were used to detect the CYBB gene variant (c.804 + 2T>C, splicing) in this family.

INTERVENTIONS

The patient was treated with IVF and PGT-M successively.

OUTCOMES

In this IVF cycle, 7 embryos were obtained, and 2 of them were euploid and lacked the CYBB gene variant (c.804 + 2T>C). The PGT results were verified by prenatal diagnosis after successful pregnancy, and a healthy girl was eventually born.

CONCLUSION

PGT-M is an effective method for helping families with these fatal and rare inherited diseases to have healthy offspring. It can availably block the transmission of disease-causing loci to descendant.

[Genetic counseling for hearing loss today]

Genetic counseling for hearing loss today originated from decoding the genetic code of hereditary hearing loss, which serves as an effective strategy for preventing hearing loss and constitutes a crucial component of the diagnostic and therapeutic framework. This paper described the main principles and contents of genetic counseling for hearing loss, the key points of counseling across various genetic models and its application in tertiary prevention strategies targeting hearing impairment. The prospects of an AI-assisted genetic counseling decision system and the envisions of genetic counseling in preventing hereditary hearing loss were introduced. Genetic counseling for hearing loss today embodies the hallmark of a new era, which is inseparable from the advancements in science and technology, and will undoubtedly contribute to precise gene intervention!

Evolution and Utility of Preimplantation Genetic Testing for Monogenic Disorders in Assisted Reproduction - A Narrative Review

Preimplantation genetic testing (PGT) for monogenic disorders and assisted reproductive technology have evolved and progressed in tandem. PGT started with single-cell polymerase chain reaction (PCR) followed by fluorescent in situ hybridisation for a limited number of chromosomes, later called 'preimplantation genetic diagnosis (PGD) version 1'. This review highlights the various molecular genetic techniques that have evolved to detect specific inherited monogenic disorders in the preimplantation embryo. Literature review in English was performed in PubMed from 1990 to 2021, using the term 'preimplantation genetic diagnosis'. With whole-genome amplification, multiple copies of embryonic DNA were created. This helped in avoiding misdiagnosis caused by allele dropout. Multiplex fluorescent PCR analysed informative short tandem repeats (STR) and detected mutations simultaneously on automated capillary electrophoresis sequencers by mini-sequencing. Comparative genomic hybridisation (CGH) and array CGH were used for 24 chromosome aneuploidy screening. Subsequently, aneuploidies were detected by next-generation sequencing using single-nucleotide polymorphism arrays, while STR markers were used for haplotyping. 'PGD version 2' included accurate marker-based diagnosis of most monogenic disorders and detection of aneuploidy of all chromosomes. Human leukocyte antigen matching of embryos has important implications in diagnosis and cure of haemoglobinopathies and immunodeficiencies in children by means of matched related haematopoietic stem cell transplantation from an unaffected 'saviour sibling' obtained by PGT.