Single-cell polymerase chain reaction-based pre-implantation genetic diagnosis using fragment analysis for β-thalassemia in an Indian couple with β-globin gene mutations

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.

Whole genome amplification induced bias in the detection of KRAS-mutated cell populations during colorectal carcinoma tissue testing

Whole genome amplification replicates the entire DNA content of a sample and can thus help to circumvent material limitations when insufficient DNA is available for planned genetic analyses. However, there are conflicting data in the literature whether whole genome amplification introduces bias or reflects precisely the spectrum of starting DNA. We analyzed the origins of discrepancies in KRAS (Kirsten rat sarcoma viral oncogene homolog gene) mutation detection in six of ten samples amplified using the GenomePlex® Tissue Whole Genome Amplification kit 5 (WGA5; Sigma-Aldrich, St. Louis, MO, USA) and KRAS StripAssay® (KRAS SA; ViennaLab Diagnostics, Vienna, Austria). We undertook reextraction, reamplification, retyping, authentication, reanalysis, and reinterpretation to determine whether the discrepancies originated during the preanalytical, analytical, and/or interpretative phase of genotyping. We conclude that a combination of glass slide/sample heterogeneity and biased amplification due to stochastic effects in the early phases of whole genome amplification (WGA) may have adversely affected the results obtained. Our findings are relevant for both forensic genetics testing and massively parallel sequencing using preamplification.

Control of Thalassemia in India

The β-thalassemias and sickle cell disorders pose a major health burden in the large and diverse Indian population. Education programs for awareness generation are being done by National Institutions, non-governmental organizations and Thalassemia Societies in different states. Several extensive epidemiological studies have shown that there are many non-tribal and tribal communities where the prevalence of b-thalassemia carriers is much higher (5.3 to 17.0%) than the average of 3 to 4% projected for the entire country. These variations have also been shown within small geographic regions in some states, emphasizing the need for micro mapping to estimate the true burden of disease. There are 10 to 12 centers where prenatal diagnosis for hemoglobinopathies is done and the Indian Council of Medical Research is establishing additional regional centers in states where they are most needed. Sixtyeight b-thalassemia mutations have been described so far among Indians and the knowledge on their prevalence and regional distribution has helped to undertake prenatal diagnosis in a cost effective way.

Pre-implantation genetic screening using fluorescence in situ hybridization in couples of Indian ethnicity: Is there a scope?

CONTEXT:

There is a high incidence of numerical chromosomal aberration in couples with repeated in vitro fertilization (IVF) failure, advanced maternal age, repeated unexplained abortions, severe male factor infertility and unexplained infertility. Pre-implantation genetic screening (PGS), a variant of pre-implantation genetic diagnosis, screens numerical chromosomal aberrations in couples with normal karyotype, experiencing poor reproductive outcome. The present study includes the results of the initial pilot study on 9 couples who underwent 10 PGS cycles.

AIM:

The aim of the present study was to evaluate the beneficial effects of PGS in couples with poor reproductive outcome.

SETTINGS AND DESIGN:

Data of initial 9 couples who underwent 10 PGS for various indications was evaluated.

SUBJECTS AND METHODS:

Blastomere biopsy was performed on cleavage stage embryos and subjected to two round fluorescence in situ hybridization (FISH) testing for chromosomes 13, 18, 21, X and Y as a two-step procedure.

RESULTS:

Six of the 9 couples (10 PGS cycles) conceived, including a twin pregnancy in a couple with male factor infertility, singleton pregnancies in a couple with secondary infertility, in three couples with adverse obstetric outcome in earlier pregnancies and in one couple with repeated IVF failure.

CONCLUSION:

In the absence of availability of array-comparative genomic hybridization in diagnostic clinical scenario for PGS and promising results with FISH based PGS as evident from the current pilot study, it is imperative to offer the best available services in the present scenario for better pregnancy outcome for patients.