We performed a clinical and genetic study of patients affected by cavernous angiomas (CA) of the nervous system. We examined initial signs and symptoms in sporadic and familial cases. We obtained clinical, neuroimaging and genetic data on 15 Italian patients with CA of the nervous system with positive, doubtful or apparently negative family history. Genetic markers surrounding three different gene regions (7q, 3q and 7p) were analysed. In one small family, genetic linkage was consistent with all chromosome loci. In another family with the unusual association of cerebral and spinal CA, linkage with chromosome 7q and, likely, 7p was excluded, while linkage with locus 3q was possible. Our results indicate that Italian families with CA may show genetic heterogeneity. Non-specific and subtle onset symptoms hide the presence of CA within families. Patients with multiple CA may have silent cerebral lesions confirming the low penetrance of clinical signs in spite of radiological ones.