tailieunhanh - Chapter 062. Principles of Human Genetics (Part 30)

DNA testing is performed by mutational analysis or linkage studies in individuals at risk for a genetic disorder known to be present in a family. Mass screening programs require tests of high sensitivity and specificity to be costeffective. Prerequisites for the success of genetic screening programs include the following: that the disorder is potentially serious; that it can be influenced at a presymptomatic stage by changes in behavior, diet, and/or pharmaceutical manipulations; and that the screening does not result in any harm or discrimination. Screening in Jewish populations for the autosomal recessive neurodegenerative storage disease Tay-Sachs has reduced the. | Chapter 062. Principles of Human Genetics Part 30 DNA testing is performed by mutational analysis or linkage studies in individuals at risk for a genetic disorder known to be present in a family. Mass screening programs require tests of high sensitivity and specificity to be costeffective. Prerequisites for the success of genetic screening programs include the following that the disorder is potentially serious that it can be influenced at a presymptomatic stage by changes in behavior diet and or pharmaceutical manipulations and that the screening does not result in any harm or discrimination. Screening in Jewish populations for the autosomal recessive neurodegenerative storage disease Tay-Sachs has reduced the number of affected individuals. In contrast screening for sickle cell trait disease in African Americans has led to unanticipated problems of discrimination by health insurers and employers. Mass screening programs harbor additional potential problems. For example screening for the most common genetic alteration in cystic fibrosis the AF508 mutation with a frequency of 70 in northern Europe is feasible and seems to be effective. One has to keep in mind however that there is pronounced allelic heterogeneity and that the disease can be caused by 1400 other mutations. The search for these less common mutations would substantially increase costs but not the effectiveness of the screening program as a whole. Occupational screening programs aim to detect individuals with increased risk for certain professional activities . a1 antitrypsin deficiency and smoke or dust exposure . Mutational Analyses DNA sequence analysis is increasingly used as a diagnostic tool and has significantly enhanced diagnostic accuracy. It is used for determining carrier status and for prenatal testing in monogenic disorders Chap. 64 . Numerous techniques are available for the detection of mutations Table 62-9 . In a very broad sense one can distinguish between techniques that allow for .