Medical Science: Updates and Prospects Vol. 12

Cell-free DNA (cfDNA) analysis has become an important component of contemporary prenatal screening because it enables the assessment of selected foetal genetic conditions using a maternal blood sample. Cell-free foetal DNA (cffDNA) originates mainly from placental trophoblasts and circulates in maternal plasma as a fraction of total cfDNA. Its detection has supported the development of non-invasive prenatal testing (NIPT), particularly for common foetal aneuploidies involving chromosomes 21, 18 and 13. The approach has also been applied to foetal sex determination, foetal RhD genotyping, copy-number variation assessment and selected single-gene disorders. These applications are supported by advances in next-generation sequencing, targeted sequencing, single-nucleotide polymorphism-based analysis and related molecular methods. Compared with invasive procedures such as amniocentesis and chorionic villus sampling, cfDNA testing avoids procedure-related foetal risk because it requires only maternal blood collection. However, it remains a screening approach in most clinical settings and should not be considered a universal substitute for diagnostic testing. Results may be influenced by low foetal fraction, placental mosaicism, maternal genetic background, technical limitations and bioinformatic interpretation. Positive or uncertain findings, therefore, require appropriate counselling and confirmatory diagnostic evaluation. This chapter summarises the biological origin of cffDNA, the laboratory approaches used for its analysis, the major clinical applications in prenatal care, and the current limitations affecting interpretation and implementation. The available evidence supports cfDNA testing as a valuable tool in prenatal screening when used with careful clinical judgement, standardised protocols, and adequate genetic counselling.