TY - CHAP M1 - Book, Section TI - DNA Analysis A1 - Pyeritz, Reed E. A2 - Papadakis, Maxine A. A2 - McPhee, Stephen J. A2 - Rabow, Michael W. A2 - McQuaid, Kenneth R. PY - 2023 T2 - Current Medical Diagnosis & Treatment 2023 AB - Direct inspection of nucleic acids—often called “molecular genetics” or “DNA diagnosis”—is an important tool in a number of clinical areas, including oncology, infectious disease, forensics, and the general study of pathophysiology. A major impact has been in the diagnosis of mendelian disorders. Molecular testing is available for more than 3000 separate hereditary conditions. Once a particular gene is shown to be defective in a given condition, the nature of the pathogenic variant in a patient can be determined by sequencing the nucleotides of the coding exons and the splice sites. One of a variety of techniques can then be used to determine whether that same pathogenic variant is present in other patients with the same disorder. Genetic heterogeneity is so extensive that most mendelian conditions are associated with numerous pathogenic variants at one locus—or often multiple loci—that produce the same phenotype. Pathogenic variants at several hundred different genes cause vitreoretinal disorders, such as retinitis pigmentosa, and changes in several dozen genes cause familial hypertrophic cardiomyopathy. This fact complicates DNA diagnosis of patients and screening for carriers of defects in specific genes. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/10/04 UR - accessmedicine.mhmedical.com/content.aspx?aid=1193140299 ER -