Studies of diseases
Genetic analyzes are currently being used in prenatal diagnosis, pre-implantation genetic diagnosis (PID), which is highly controversial and currently not authorized in Germany, in which an artificially fertilized embryo is examined for hereditary diseases and chromosome aberrations before planting, as well as for health care or genetic counseling used when trying to conceive. Thus, statistical probabilities for the development of some diseases can be predicted (eg for breast cancer in certain female carriers) or for the transmission of a hereditary disease to the children. The following methods are used for this:
- DNA sequencing: In principle, a number of different methods are used for this purpose, often based on the principle of fragmenting the DNA with enzymes, artificially amplifying them (often with the polymerase chain reaction = PCR) and then determining their lengths or looking for patterns in the DNA strands. The examined sections are then compared with those in healthy genes. Prenatal diagnosis also utilizes fluorescence in situ hybridization (FISH), which studies the chromosomes in the cell nuclei with specific probes coupled with a fluorescent dye. Thus, gender and changes in the chromosomes in terms of number or structure can be determined.
- Mapping of Chromosomes: Also suitable for this are various methods. For example, the chromosomes in a cell can be photographed and sorted by microscope and staining according to structural criteria (karyogram). This can determine the gender of an individual and detect or exclude some hereditary diseases such as Down's syndrome. Other methods of genetic research (eg pedigree analysis, linkage analysis) are used to map and clarify questions, such as how a particular disease is inherited.