Information on Genetic Epidemiology
Background: The genetic causes of a variety of diseases have been known for long. Mucoviscidosis (cystic fibrosis), e.g., is due to a defect at the long arm of chromosome 7. The respective gene is coding for a protein having the function of a channel in the cell membrane. The gene defect modifies the protein and hence the channel function. This is called a monogenetic disorder as only one gene is concerned, whereas in the development of complex diseases, as e.g. cardiovascular diseases, cancer, diabetes and extreme obesitiy (adiposity), numerous genetic, but also environmental and life-style factors have a substantial share. Presently these factors and their interaction are being researched in worldwide studies. Also the genetics of complex characteristics as body height, left- or right-handedness or diverse blood values have not yet been understood in detail.
Methodology: A significant characteristic of the genome is its diversity. There are gene sections that contain the same information in all human-beings but there are also many sections that vary in every individual. Every person, for example, has its unique "genetic finger print".
With new technologies it has been possible for some years to determine thousands of tiny differences (the so-called "SNPs", single nucleotide polymorphisms) among the study participants. DNA isolated from blood samples is applied to fingernail-sized chips; DNA pieces bind to prefabricated complementary and known DNA samples and can thus be identified. Consequently, new huge data sets are formed containing more than one million genetic information about one single person.
The so-called genome-wide association studies (GWAS) are searching for correlations between certain diseases and certain gene variations. If, for example, a SNP is to be seen particularly often in persons with hypertension, the function of the relating gene is examined more closely to search for a potential effect path from gene to hypertension.
Examples in KORA: In the frame of the KORA study many diverse diseases and its genetic causes have been investigated since 2006, often in collaboration with scientists from all over the world. Only recently a gene was described evidently having an impact on the uric acid blood level and thus on the development of gout. Even unknown genes related to body height could be identified. In the course of a major project with 90 scientists participating from more than 40 centers six new genes could be classified that are associated with type 2 diabetes.
Future application: At present genetic knowledge is not offering therapies for those concerned. It is, however, an important precondition for developing purposeful healing approaches for the individual.
KORA Press Release in Genetic Epidemiology: