Gene-gene and gene-environment interplay represent specific susceptibility for different types of ischaemic stroke and leukoaraiosis.

Stroke is a very frequent entity. It is the third leading cause of death and the leading cause of adult disability in the developed world. At a population level, the common sporadic form of ischaemic stroke is underpinned by both environmental and genetic risk factors. Typically, in clinical practice, environmental risk factors such as hypertension, diabetes mellitus, smoking, alcohol consumption, and other factors, are usually considered to be more important than genetic factors. However, it is the interplay of both environmental and common genetic factors [such as the Leiden V, methylenetetrahydrofolate reductase C677T, apolipopotein E 4, endothelial nitric oxide synthase G894T, angiotensin-converting enzyme I/D and angiotensin II type 1 receptor A1166C mutations and polymorphisms] that leads to the development of ischaemic stroke. Indeed, a complex network of interactions between genetic factors and clinical risk factors can be supposed. This review evaluates the possible roles of gene-gene and gene-environment interactions concerning the above genetic factors in the evolution of ischaemic stroke and leukoaraiosis. A knowledge of the specific genetic patterns which are associated with a significant risk of ischaemic stroke or leukoaraiosis may also draw attention to a large population at an increased risk of circulatory disorders. This may facilitate the choice of more effective and specific prevention on the basis of the genotype.