[Genetics of cerebral vascular accidents]

Ischaemic or haemorrhagic cerebral vascular accidents (CVA) are the second cause of premature death in Western countries. Their pathophysiological mechanisms are very heterogeneous and implicate environmental and genetic factors. The recent identification of several genes implicated in the rare monogenic forms of CVA, such as hereditary cerebral amyloid angiopathy, cerebral cavernous angioma or CADASIL, has had immediate diagnostic applications for patients and their relatives, and has opened new insights into the mechanisms governing angiogenesis and/or vascular homeostasis. In the multifactorial forms of CVA, by far the most frequent, the role of a genetic factor is much more moderate, making identification of the implicated genes difficult. A very great number of association studies have been performed in order to examine the possible implication of candidate genes due to their known or supposed functions, but very few genetic variants have been associated with an increased risk of CVA, this increase being modest moreover. Quite recently an approach combining genetic linkage analysis and a haplotypic association study has allowed the localisation and identification of a new gene, phosphodiesterase 4D, implicated in ischaemic CVA, and the localisation on chromosome 7 of a gene implicated in the occurrence of cerebral aneurysms, thus raising new hopes in these multifactorial form.