Genetic testing, which up until recently was used as a diagnostic tool for a relatively limited number of rare Mendelian diseases, has recently undergone a huge expansion. This development is due to two factors: first, the development of the DNA sequencing project of the human genome and progress of large-scale genotype testing technologies and, secondly, to a greater comprehension of the risk of disease development, including those diseases possessing a strong environmental component which, etiologically, are strongly influenced by individual genetic constitution.
Today it is possible to predict the risk of common and complex disease development (for example cancer, inflammatory and auto-immune diseases, cardiovascular diseases and diabetes) in healthy individuals by associating risk factors with genetic polymorphisms which are present in the human population. In such a context, genetic research is growing ever more important in the field of medical diagnosis. Clinical advancement in the study of various diseases (and their subsequent treatment) is strongly determined by individual genetic characteristics. Equally attractive, are the possibilities that medical genetics offers in terms of prognosis and disease treatment.
Example of a genetic test carried out on a carrier family of the dilated cardiomyopathy gene mutation.
Ku L. Circulation. 2003. 108;118-121
In this case, if an MCD gene mutation is found and if the phenotype is MCD and/or arrhythmia, the gene mutation is, most likely, the cause of such cardiac complications or has, at least, a relevant role in their development. If no evidence for cardiac disease is found but the test for familial gene mutation comes back positive, than this signifies that the individual has a higher risk of developing cardiomyopathy and/or arrhythmia in the future.
As to the carrier of the individual or familial gene mutation who shows, as of yet, no symptoms, the probability that his/her descendents inherit the same mutation is of 50% which will consequently posit the next generation at a higher risk of developing cardiac complications.