Author: Fan Jin

Publisher: Frontiers Media SA

Published: 2020-06-22

Total Pages: 117

ISBN-13: 2889637395

Birth defects are one of the major public health concerns in the world, as they cause approximately 20% of infant deaths. Genetic disorders, including chromosome abnormalities and single gene disorders, are the most common causes of birth defects for which there is no efficient treatment. Prenatal genetic screening and diagnosis allow early identification of affected conceptuses and facilitates reproduction planning or counseling. Molecular technologies have developed rapidly in recent years and have been widely used in screening and diagnosis of genetic disorders at all stages of prenatal development (e.g. pre-implantation, embryonic and fetal). However, their performance still needs to be validated and assessed as the balance between their advantages and disadvantages need to be discussed. With the ability to detect copy number variations (CNVs), polyploidy, uniparental disomy and maternal cell contamination, SNP-based chromosomal microarray analysis (CMA) is showing the unique importance in diagnosing chromosomal abnormalities. The interpretation of CNVs remains a challenge; however, ultrasound and biochemical screening improve the diagnosis of fetal chromosomal abnormalities. Whole exome sequencing (WES) and whole genome sequencing (WGS) play increasingly significant roles in prenatal and carrier screening for genetic disorders. NGS-based non-invasive prenatal screening (NIPS) is now widely used for detecting common autosomal aneuploidies and has shown the potential of detecting microdeletions and microduplications. However, further investigations of the sensitivity and accuracy are required and large-scale data is necessary to evaluate the performance and clinical applications of current and new methods. Recently, reports of application of newer technologies in prenatal setting became available. Examples include third generation sequencing (reading the nucleotide sequences at the single molecule level), digital PCR (used for direct quantification of DNA) and cell-based NIPT. In the followed listed papers, the authors showed their successful experiences in identifying novel mutation, detecting low-level mosaicism or de novo mutations limited in germline cells, investigating the association of the CNVs with specific phenotypic alterations by using WES, CMA, digital PCR and some other new-developed molecular techniques. More interesting, the authors also presented a report about the evaluation of diagnostic yield in fetal WES, which suggested a new tendency to apply WES or WGS directly for prenatal diagnosis. We believed that the efficiency of scanning causative mutations and prenatal or preimplantion genetic diagnosis for genetic disorders will further improved based on the technologies of whole genomic sequencing with further improved output and resolution. New techniques, such as quick-WES for the newborn in intensive care unit, direct-WGS for prenatal diagnosis and non-invasive test for fetal monogenic disorders, will become available in the near future.