Подтема 3. Генетическая диагностика наследственных и инфекционных заболеваний

1. Gene Diagnostics is the testing of DNA for mutations that could lead to a number of diseases and or genetic disorders. A very accurate diagnosis can be made on a wide array of genetic disorders by doing a genetic test or screening. A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions. Genetic testing (also called DNA-based tests) is among the newest and most sophisticated of techniques used to test for genetic disorders which involves direct examination of the DNA molecule itself. Other genetic tests include biochemical tests for such gene products as enzymes and other proteins and for microscopic examination of stained or fluorescent chromosomes. Genetic tests are used for several reasons, including:

- identifying unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to be expressed, these are some examples:

- preimplantation genetic diagnosis (see the side bar, Screening Embryos for Disease)

- prenatal diagnostic testing [e.g. phenylketonuria (PKU) - an autosomal recessive metabolic genetic disorder characterized by a mutation in the gene for the hepatic enzyme phenylalanine hydroxylase (PAH), rendering it nonfunctional]

- newborn screening

- genealogical DNA test (for genetic genealogy purposes)

- presymptomatic testing for predicting adult-onset disorders such as Huntington's disease

- presymptomatic testing for estimating the risk of developing adult-onset cancers and Alzheimer's disease

- confirmational diagnosis of a symptomatic individual

- forensic/identity testing