Clustering of variations and haplotype analysis in the highly variable region of exon 11 of BRCA1 in Chinese women with sporadic breast cancer.

Studies on mutations of BRCA1 gene in Oriental populations, especially in Chinese are sparse. To evaluate the contribution of BRCA1 mutations to sporadic breast cancer in Chinese, mutations in exon 11 from nucleotide positions 3533 to 3682(U14680), a highly variable region of BRCA1 gene, were screened by single-strand conformation polymorphism (SSCP) and DNA sequencing in 329 genomic DNAs from 95 Chinese women with sporadic breast cancer, 29 with benign breast disease and 50 controls. As results, 6 single nucleotide changes were found, and 5 of them (3545A>G, 3551G>T, 3607C>T, 3646T>A and 3661T>C) were newly discovered. The 3545A>G and 3607C>T were germline variations, and the other 3 were somatic variations. In addition, four new haplotypes were defined. Since these newly discovered nucleotide changes were only detected in patients, our results suggest that BRCA1 may also play a role in the development of sporadic breast cancer in Chinese populations.