Background: Cavernous angiomas, which are vascular malformations mostly located in the central nervous system, may be inherited as an autosomal dominant disorder known as familial cerebral cavernoma (FCC). FCC has been studied in Hispanoamerican families, in which a strong founder effect was shown. We studied the families of 57 non-Hispanic patients with cavernous angiomas.
Methods: All 28 neurosurgery centres in France collaborated in the study. Inclusion criteria were: families of index patients known to have at least one clinically affected relative, and families of index patients with multiple cavernous angiomas who initially presented as sporadic cases. Clinical and cerebral magnetic resonance imaging (MRI) investigations were done in all patients and in other at-risk individuals who consented to take part.
Findings: On MRI, 16 of 22 sporadic index patients had relatives with cavernous angiomas. 51 multiple-case families, including 100 patients with symptoms and 164 symptom-free individuals had MRI lesions. Most FCC patients had multiple lesions and there was a strong correlation between number of lesions and age (p<0.01). The sensitivity of gradient-echo sequences was higher than that of standard MRI for detection of small cavernous angiomas. Pattern of inheritance was autosomal dominant, with incomplete clinical penetrance. The occurrence of de-novo mutations was strongly suggested in some families.
Interpretation: Neuroimaging penetrance of FCC is much higher than clinical penetrance. 75% of sporadic cases with multiple lesions are in fact familial cases. The proportion of patients developing clinical symptoms is higher in the hereditary form than in the sporadic form of the disorder.