FREQUENT OCCURRENCE OF BRCA2 LINKAGE IN ICELANDIC BREAST-CANCER FAMILIES AND SEGREGATION OF A COMMON BRCA2 HAPLOTYPE

Cloning of a breast cancer-predisposing gene (BRCA2) on chromosome 13q 12-14 has been reported recently. We analyzed seven large Icelandic br east cancer families with markers from the BRCA2 region. Five families showed strong evidence of linkage. The maximum two-point LOD scores f or the five BRCA2-linked families ranged from 1.06 to 3.19. Haplotype analyses revealed a region with identical allele sizes between the fam ilies, suggesting that they have inherited the mutation from a common ancestor. Cancer types other than breast cancer occur in individuals, segregating the affected haplotype within these families. This suggest s that mutations in the gene may also confer some risk of other malign ancies in both males and females.