Cerebral cavernous malformations (CCM) are vascular anomalies, sometimes inherited as an autosomal dominant trait, which can cause strokes and seizures. Recently, mutations of the CCM1 gene (chromosome 7q) have been found in a subset of families. The authors found 10 new mutations by screening 29 families and five seemingly sporadic cases of CCM. The mutations predicted truncation of the Krit1 mRNA encoded by CCM1, supporting the contention that CCM result from loss of Krit1 protein function and the possibility that this protein acts as a tumor suppressor.