Methods. We compared the segregation of genetic markers and clinical cases of cavernous malformation in Hispanic-American kindreds with familial disease; we also compared the alleles for markers linked to cavernous malformation in patients with familial and sporadic cases.

Results. All kindreds with familial disease showed linkage of cavernous malformation to a short segment of chromosome 7 (odds supporting linkage, 4x10(10):1), Forty-seven affected members of 14 kindreds shared identical alleles for up to 15 markers linked to the cavernous-malformation gene, demonstrating that they had inherited the same mutation from a common ancestor. Ten patients with sporadic cases also shared these same alleles, indicating that they too had inherited the same mutation. Thirty-three asymptomatic carriers of the disease gene were identified, demonstrating the variability and age dependence of the development of symptoms and explaining the appearance of apparently sporadic cases.

Conclusions. Virtually all cases of familial and sporadic cavernous malformation among Hispanic Americans of Mexican descent are due to the inheritance of the same mutation from a common ancestor. (C) 1996, Massachusetts Medical Society.