Chapter 28: Genetics and DNA-Based Technology in Clinical Biochemistry

Genetics and DNA-Based Technology in Clinical Biochemistry begins with fundamental principles of molecular biology, detailing the double-helix structure of DNA, the significance of coding exons versus non-coding introns, and the central processes of replication, transcription, and translation. The text examines diverse inheritance patterns, including autosomal dominant and recessive traits, as well as X-linked inheritance, illustrated through clinical examples such as familial hypercholesterolaemia, cystic fibrosis, and haemophilia. A significant portion of the material is dedicated to advanced diagnostic methodologies, explaining how genetic material is extracted and analyzed through techniques like gel electrophoresis and hybridization with specific probes. Key laboratory methods such as Southern and Northern blotting are discussed for identifying DNA and RNA abnormalities, alongside the use of restriction endonucleases to detect polymorphisms and restriction fragment length polymorphisms (RFLPs). The chapter highlights the revolutionary impact of the Polymerase Chain Reaction (PCR) and its specialized variants, such as the amplification refractory mutation system (ARMS), in exponentially amplifying genetic material to diagnose single nucleotide mutations. Practical clinical applications are thoroughly reviewed, covering the molecular diagnosis of muscular dystrophies, alpha-1-antitrypsin deficiency, lipid disorders, and hereditary haemochromatosis. Furthermore, it addresses the utility of genetic technology in neonatal screening for phenylketonuria, prenatal diagnosis of sickle cell anaemia, and the rapid detection of infectious pathogens like HIV and Hepatitis C. Finally, the role of DNA fingerprinting in forensic science and paternity testing is acknowledged, emphasizing the indispensable nature of DNA-based technology in modern medical diagnostics and metabolic medicine.