The most intuitively obvious example is height: short parents tend to have short children, tall parents tend to have tall children.
Diet can influence height, butinherited genes are a strong determinant of height.
It is a similar situation in common diseases, such as arthritis, diabetes, vascular disease, inflammatory bowel disease.
They are known as 'polygenic', meaning that the inherited component results from a number ofsusceptibility genes working together.
No gene, in isolation, is able to cause disease, each gene increases risk and when a threshold of risk factors, comprised of genes and environment is reached, disease results.
Recently Drs Merriman, Jones and Roberts of the University of Otago were awarded programme funding from the New Zealand Health Research Council to study the genetic causes of five common diseases: gout, rheumatoid arthritis, abdominal aortic aneurysm, inflammatory bowel disease and schizophrenia.
The programme will co-ordinate the study of genes and outcomes in these diseases.
The primary strategy will beto compare the frequency of genetic variants between cohorts ofpeople with disease ('cases') and people without disease ('healthy controls').
Sometimes individual genes will be tested, and sometimesall the ~25,000 genes in the human genome will be testedsimultaneously.
Genetic links between the mutually exclusive diseasesof rheumatoid arthritis and schizophrenia will be tested, and susceptibility genes that might be shared between diseases that have an immune component (eg rheumatoid arthritis, inflammatory diseaseand abdominal aortic aneurysm) will be investigated.
The individual projects in the programme will be strengthened by shared clinical resources and genetic technologies.
Of much importance to theprogramme is the involvement of clinical researchers from the fieldsof rheumatology, surgery, gastroenterology and clinical pharmacology.
In the long-term it is hoped that the programme will lead to advancesin the knowledge of the pathogenesis of common disease.
The research may lead to the discovery of validated drug targets, and thedevelopment of genetic tests to predict, diagnose and predict outcomein common disease.
In addition, the programme will build capabilityin biomedical genetics within this country which will be crucial toadvancing research into New Zealand's unique populations.
- Dr Tony Merriman, Senior Research Fellow, Department of Biochemistry.