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6 recordsLinked to original sources
PubMed2026

Prospective clinical validation of targeted long-read sequencing for preimplantation genetic testing of α-thalassaemia.

BACKGROUND: Preimplantation genetic testing for monogenic disorders (PGT-M) can prevent transmission of severe α-thalassaemia, but conventional workflows remain limited by family-specific assay design for direct variant detection, dependence on additional family samples for haplotype construction, and labour-intensive multi-step procedures across several platforms. Targeted long-read sequencing-based PGT-M for α-thalassaemia (tlrPGT-α-thal) integrates direct variant detection and haplotype linkage analysis within a single assay, but prospective clinical validation is lacking. METHODS: This prospective clinical study enrolled 103 families at high risk of transmitting α-thalassaemia at a reproductive medicine centre between August 2024 and March 2025. All families underwent blinded parallel analysis using both conventional NGS-based PGT-M (comparator) and tlrPGT-α-thal. RESULTS: In the primary concordance analysis, tlrPGT-α-thal was fully concordant with conventional NGS-based PGT-M (507/507, 100.0%; exact 95% CI, 99.3-100.0). Direct variant detection was successful in 501/507 embryos (98.82%; 95% CI, 97.4-99.6), haplotype linkage was established in 505/507 embryos (99.61%; 95% CI, 98.6-100.0), and one meiotic recombination event was identified. Among 93 families proceeding to embryo transfer, 57 pregnancies underwent invasive prenatal diagnosis, and all were concordant with the corresponding tlrPGT-α-thal results. Of the 26 comparator-inconclusive embryos, tlrPGT-α-thal resolved 6 complex cases, including cases with incomplete pedigrees or insufficient informative SNPs. Among the remaining 20 embryos with HBA-region aneuploidies, genotype and parental origin could be determined in 12. CONCLUSIONS: The findings show that tlrPGT-α-thal enables direct detection of diverse α-thalassaemia-causing variants together with efficient haplotype linkage analysis within a single workflow, without requiring family-specific assay design or additional family samples. The method demonstrated high diagnostic accuracy while providing added value in complex scenarios. Taken together, tlrPGT-α-thal represents a simplified and broadly applicable strategy for α-thalassaemia PGT-M.

Humans↗
PubMed2026

Preimplantation genetic testing for concurrent Meckel Syndrome and hereditary breast cancer in a Chinese family harboring a novel NPHP3 pathogenic variant and a canonical BRCA2 frameshift variant.

Meckel syndrome (MKS) is a lethal autosomal recessive disease with high phenotypic and genetic heterogeneity. Defects in NPHP3 cause MKS type 7. Herein, we report a case of a Chinese family with a newborn male proband presenting with occipital encephalocele and polycystic kidneys. Whole-exome sequencing was performed on genomic DNA extracted from peripheral blood. Potential variants were assessed for pathogenicity. Two compound heterozygous variants of NPHP3 (c. 950T>C, p. Phe317Ser, and c.2694-2_2694-1delAG) were identified, which were inherited from both parents, with c.950T>C representing a novel variant. Two BRCA2 variants (c.5576_5579delTTAA, p. Ile1859Lysfs*3, and c.9357A>C,p. Leu 3119 Phe) were identified, which were inherited from the father. After the proband was diagnosed with MKS7, the couple chose preimplantation genetic testing for monogenic disorders (PGT-M) to simultaneously prevent the transmission of NPHP3 and BRCA2 pathogenic variants, leading to a successful pregnancy. Our study expands the NPHP3 variant spectrum and contributes to the molecular diagnosis and genetic counseling of MKS. This case indicates that PGT-M is a viable option for NPHP3-related MKS and BRCA-positive patients to avoid transmission while maintaining their families. Successful application of PGT-M provides a potential approach for treating other monogenic diseases.

Journal Article↗
PubMed2026

A Comprehensive Survey and Evaluation of Preimplantation Genetic Testing Practices in Canadian Assisted Reproductive Technology Clinics.

OBJECTIVES: In Canada, access to provincial funding for fertility treatments, such as in vitro fertilization (IVF) and preimplantation genetic testing (PGT), vary significantly. Despite rising demands, the lack of data on current practices across Canadian assisted reproductive technology (ART) clinics has contributed to the absence of standardized guidelines to support clinics offering these services. This pilot study surveys fertility clinics to examine current demands and practices related to PGT, while also exploring providers' perspectives on its implementation and future applications. METHODS: A 40-question survey was distributed to Canadian ART clinics offering IVF and PGT services. RESULTS: The responses confirm that there is a high demand for IVF and PGT services. Although clinical criteria for PGT for aneuploidy (PGT-A) were generally consistent across clinics, views on its effectiveness and eligibility for public funding varied. PGT for monogenic disorders (PGT-M) appears to be widely available, and respondents showed strong support for public funding in cases involving serious heritable conditions. CONCLUSIONS: This study outlines current practice and highlights variations across clinics, while also presenting the perspectives of providers of ART clinics throughout Canada. It also provides a degree of foresight as to the direction the PGT practice may take in the coming years.

assisted reproductive technology↗
PubMed2026

Clinical and functional characterization of a novel homozygous non-canonical splice mutation (c.1910-15_1910-11delinsTTACA) in CEP290 causing Joubert syndrome.

BACKGROUND: Joubert syndrome (JS) is a rare, predominantly autosomal recessive neurodevelopmental disorder characterized by hypotonia, motor delay, intellectual disability, oculomotor apraxia, and the hallmark "molar tooth sign" on axial view of MRI. JS is genetically heterogeneous, with pathogenic variants identified in more than 40 genes involved in primary cilia function. Among these, CEP290 is one of the most frequently mutated genes. RESULTS: In this study, we investigated two children-an 11-year-old boy (the proband) and his 5-year-old sister-both presenting with a similar phenotype consistent with JS. The parents, who self-identified as Chechen, reported distant consanguinity. The family also included a healthy 13-year-old daughter. The proband had previously been evaluated by a neurologist and underwent whole-genome sequencing (WGS); however, no causative variants were identified initially. After phenotype reassessment by a clinical geneticist, we performed a reanalysis of the raw WGS data and identified a novel homozygous intronic variant of uncertain significance (VUS), c.1910-15_1910-11delinsTTACA in CEP290 (NM_025114.4). Sanger sequencing confirmed that both the proband and his affected sister were homozygous for this variant, which they inherited from their heterozygous parents. Their healthy sister did not carry the variant. mRNA-sequencing and targeted cDNA sequencing (read depth ~ 100,000x) demonstrated that this intronic variant causes completely aberrant splicing of CEP290 pre-mRNA. Predominantly this variant causes the skipping of exon 20 in the main CEP290 transcript. Alternatively, the variant results in partial inclusion of intron 19 into the mRNA, elongation of exon 20 by 58 nucleotides, and a homozygous substitution chr12:88114573 (ACTGTGTA> TTACAGTA). No canonical mRNA isoform was detected when the variant was homozygous. Both the predicted severe truncation and the likely degradation of aberrant transcripts through nonsense-mediated decay (NMD) would correspond to complete loss of CEP290 function. Following the reclassification of this VUS to likely pathogenic, the family was able to pursue in vitro fertilization (IVF) with preimplantation genetic testing for monogenic disorders (PGT-M). CONCLUSION: Our study highlights the critical importance of proper phenotyping prior to referral for WES/WGS as well as of combining NGS with functional mRNA studies to achieve a molecular diagnosis for patients with predicted splice-site mutations in JS-associated genes. It also emphasizes the need for functional reassessment of VUS when genomic data are expected to guide reproductive decision-making within affected families.

Humans↗
PubMed2026

Prevalence and mechanistic origins of genome-wide ploidy abnormalities in ICSI derived human preimplantation embryos.

BACKGROUND: Genome-wide ploidy abnormalities (GWPA) constitute a distinct and clinically significant class of chromosomal errors that arise during human preimplantation development. However, the developmental origins and prevalence of GWPA remain incomplete and poorly understood. METHODS: To evaluate the frequency and origin of GWPA in human embryos, we have retrieved preimplantation genetic testing (PGT) haplotyping data, derived from 3798 blastomere and 3593 trophectoderm biopsies. Prior haplotype reconstruction and determination of parental origin were performed using B-allele frequency-aware haplotyping (haplarithmisis). RESULTS: GWPA were detected in 113 biopsies: 81 cleavage-stage embryos and 32 blastocysts. Genome-wide loss of heterozygosity of maternal origin was the most frequent abnormality. Triploidy was the second most common aberration present in 35 embryos: 24 cleavage-stage embryos and 11 blastocysts, with the majority resulting from maternal meiosis II errors. In addition, we uncover less-characterized abnormalities, providing new insights into the chromosomal mechanisms driving early human embryonic development. CONCLUSIONS: GWPA occur in 2.16% of cleavage-stage and 0.89% of blastocyst-stage ICSI embryos, showing a strong selection against GWPA during preimplantation development. This study also demonstrates that using appropriate methods to detect GWPA when screening ICSI embryos can help prevent the transfer of nonviable embryos.

Humans↗
PubMed2024

A healthy live birth after mosaic blastocyst transfer in preimplantation genetic testing for GATA1-related cytopenia combined with HLA matching.

BACKGROUND: GATA1-related cytopenia (GRC) is characterized by thrombocytopaenia and/or anaemia ranging from mild to severe. Haematopoietic stem cell transplantation (HSCT) is a healing therapeutic choice for GRC patients. We identified a novel pathogenic variant (GATA1: c.1019delG) in a boy with GATA1-related cytopenia. Then we performed preimplantation genetic testing (PGT) in this GRC family. After a mosaic embryo transfered, a healthy and HLA-compatible with the proband baby was delivered. CASE PRESENTATION: The proband is a 6-year-old boy who was diagnosed to have transfusion-dependent anaemia since 3 year old. Whole-exome sequencing (WES) showed that the proband has a hemizygous variant c.1019delG in GATA1, which is inherited from his mother. His parents decided to undergo PGT to have a health and HLA-compatible offspring. After whole genome amplification (WGA) of biopsied trophectoderm (TE) cells, next generation sequencing (NGS)-based PGT was preformed to analyse embryos on chromosomal aneuploidy, target mutation and HLA typing. There were 3 embryos HLA-matched to the proband. The genotypes of the 3 embryos were heterozygous variant, hemizygous variant, normal respectively. After a heterozygous, mosaic partial trisomy (chr)16, and HLA-matched embryo transfer, a healthy baby was delivered and whose HSCT is compatible with the proband. CONCLUSIONS: NGS-based PGT-HLA is a valuable procedure for the treatment of GATA1-related cytopenia caused by GATA1 variants, or other haematological disorders, oncological and immunological diseases. Furthermore, our study reconfirms that mosaic embryos transfer would bring healthy offspring.

Child↗