Chapter 17: Use of Recombinant DNA Techniques in Medicine

The polymerase chain reaction fundamentally revolutionized diagnostics by enabling exponential amplification of DNA from minute samples, while gel electrophoresis and molecular blotting techniques—Southern, Northern, and Western—permit detection and quantification of nucleic acids and proteins respectively. The chapter then explores sequencing technologies, from traditional Sanger sequencing employing dideoxynucleotides to next-generation high-throughput approaches that have dramatically reduced costs and enabled noninvasive prenatal screening, mutation detection, and infectious disease identification. Molecular profiling tools including DNA microarrays and RNA sequencing reveal patterns of gene expression critical for cancer classification, predicting drug responsiveness, and understanding pathogen biology; bioinformatics integrates these massive datasets to support personalized medical approaches. Restriction fragment length polymorphisms and DNA fingerprinting exemplify how molecular variation serves forensic investigation, paternity confirmation, and genetic disease identification. The chapter emphasizes recombinant protein production for therapeutics—human insulin, growth hormone, clotting factors, thrombolytic agents, cytokines, and interferons—produced through bacterial expression, transgenic animal systems, and yeast fermentation. Gene therapy approaches including viral vectors and RNA interference mechanisms target genetic diseases such as severe combined immunodeficiency and cystic fibrosis, though insertional mutagenesis risks underscore the importance of careful safety evaluation. The chapter concludes by addressing ethical implications of germline modification, reproductive cloning, and genome editing technologies like CRISPR-Cas systems, while highlighting proteomics approaches using mass spectrometry to identify disease biomarkers and therapeutic targets in oncology and other complex diseases.