Genetics of cerebral cavernous angioma.
Cerebral cavernous malformations (CCM) are hamartomatous vascular anomalies characterized by densely packed, grossly enlarged immature capillaries without intervening neural tissue. Depending on their location and size (ranging from a few millimeters to several centimeters), the biologically dynamic lesions become symptomatic during the second to fourth decade of life. Clinical symptoms include recurrent headaches, seizures, intracranial hemorrhage, and stroke. There are sporadic and autosomal dominantly inherited forms of CCM. Causal mutations have been demonstrated in three genes, KRIT1, MGC4607, and PDCD10, but additional genes are likely to be discovered. These genes are therefore thought to play a role in angiogenesis. Their specific modes of actions, their contribution to and their likely penetrance in the genesis of CCM are the subject of current investigations. Genetic counseling is strongly advisable for patients with a positive family history and for seemingly sporadic cases with multiple lesions, and genetic testing should be considered on an individual basis. The identification of a mutation enables precise genetic testing of relatives. Given the 50 % a priori risk of autosomal dominant inheritance, the benefits of genetic testing are twofold: a positive test result in a presymptomatic carrier permits close neuroradiological surveillance and timely neurosurgical intervention; a negative test result relieves the proband of unwarranted anxiety and unnecessary medical supervision.