Molecular Diagnostics

Genetic testing/screening makes use of a variety of technologies to identify inherited or acquired modifi-cations in the genetic information of an individual. The technologies used can be cytogenetic, as well as biochemical and immunochemical, to verify the composition of DNA, RNA, proteins, carbohydrates and lipids.The result of this testing can yield different types of information, such as: (1) confirmation or exclusion of the diagnosis of a specific disease; (2) the magnitude of the risk, or its absence, of developing a disease or reacting adversely to drugs and environmental factors; (3) the magnitude of the risk of biological descendants inheriting a defect.The tests can be performed on individuals, or on nuclear or extended families. The term 'screening' is usually reserved for the systematic testing of the members of defined populations or high-risk population subgroups for one or more inherited modifications of the genome. As the technology improves and its cost decreases, the genome of individuals may also be screened for a series of related or unrelated inherited variants. Since the composition of the chromosomes and the DNA of an individual are fixed at fertilisation, most tests can be done at any stage of life, either before or after birth (pre-implantation diagnosis, all forms of prenatal diagnosis and neonatal and adult testing). In most genetics centres, the testing of children will be strictly limited to those cases in which a diagnosis is important for management or therapy.As a result, the possibilities for testing and screening for the genes involved in inherited diseases or susceptibility to diseases have increased spectacularly. In addition, modulators of gene expression -- other genes, non-coding DNA sequences, proteins involved in the three-dimensional organisation of DNA and acquired (epigenetic) modifications of DNA -- are being ident-ified. This has led to the surprising realisation that even environmental factors, such as food components,