Gene technology, characterization of insulin gene and the relationship to diabetes research.

The development and introduction of modern molecular biological methods was a prerequisite to the characterization of the insulin gene. The transfer of chemically synthesized genes for human insulin A and B chains as well as the naturally occurring rat insulin gene into bacteria opened possibilities to produce insulin in bacterial systems. Moreover, the structure of rat I and rat II insulin genes as well as human insulin gene were determined. Structural analysis of human insulin genes isolated from a human chromosomal gene library led to the identification of allelic variants of a single human insulin gene. The human insulin gene is located on the short arm of chromosome 11. The hypothesis that structurally abnormal insulin could play a role in the development of diabetes mellitus could be proved in clinical practice. Human insulin isolated from a diabetic patient showed an abnormality in the amino acid sequence and a decreased biological activity of the hormone. This finding demonstrates that in certain cases of diabetes mellitus the synthesis of structurally abnormal insulin due to a mutation in the insulin gene can be the cause for the development of relative insulin deficiency and hyperglycaemia.