The Role of Preimplantation Genetic Testing for Monogenic Disorders (PGT-M) in Hemoglobinopathy Management-Techniques, Accuracy, and the Balancing of Benefits and Drawbacks.

Preimplantation genetic testing for monogenic disorders (PGT-M) is a powerful tool for identifying genetic disorders prior to gestation. For hemoglobinopathies like thalassemias and sickle cell disease, PGT-M offers a preventative strategy to ensure that only embryos deemed genetically healthy are transferred. A comprehensive review of 22 original articles explores and summarizes the existing evidence on PGT-M techniques in hemoglobinopathies. The review focuses on key aspects such as accuracy, benefits, and drawbacks related to various hemoglobinopathies. Given the limited quantity of DNA obtained from an embryo biopsy, whole genome amplification (WGA) is a critical step for amplifying the sample. One of the available methods of WGA, multiple displacement amplification (MDA) is one of the most widely adopted method with acceptable allele drop-out (ADO) rates for hemoglobinopathies compared with traditional methods. Dealing with ADO constitutes a primary technical obstacle in PGT-M. The failure to amplify one allele in single-cell analysis is a major factor limiting the overall diagnostic accuracy of the procedure. To mitigate this issue, PCR-based and next-generation sequencing (NGS)-based approaches are employed. These methods incorporate linkage analysis with genetic markers such as short tandem repeats (STRs) or single-nucleotide polymorphisms (SNPs) to reduce the risk of incorrect interpretations from ADO and enhance the proportion of conclusive results. A future direction for PGT-M that involves the development of non-invasive methods (niPGT) will be included and discussed.