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lb183 |
1 Biochemistry & Molecular Biology, Howard University, 520 W Street N.W., Washington, DC, 20059-0001,
2 Microbiology, Howard University, 520 W Street N.W., Washington, DC, 20059
ABSTRACT
Large genomic rearrangements have been observed in BRCA1 carriers and frequently involve recombination between intron Alu sequences, leading to a non-functional protein. Multiplex ligation-dependent probe amplification (MLPA) is a technique that can detect the change in copy number of the 24 exons of BRCA1 simultaneously in one reaction. A large deletion of exons 1a, 1b, and 2 has been detected in triplicate MLPA analyses of one (family #70) of our 55 high-risk African American breast cancer families. The BRCA1 Pro871Leu polymorphism is usually in linkage disequilibrium with the BRCA1 ß promoter C/G 1802 polymorphism. Linkage of the Pro871Leu polymorphism to the ß promoter C/G 1802 polymorphism was tested using specific ß promoter primers. In family #70, the Pro871Leu polymorphism was linked to a hemizygous/homozygous C in the ß promoter. The hemizygosity of the BRCA1 ß promoter 1802 polymorphism suggests that the deletion of exons 1a, 1b, and 2 extends into the promoter region. A 37 kb deletion has been reported in Caucasians that removes the BRCA1 promoter and BRCA1 introns 1a, 1b, and 2 resulting in no BRCA1 transcript. Due to the 98% identity of sequences in BRCA1 intron 2 and 
-BRCA1 intron2, this region is a hot spot for recombination. This is the first report of a large deletion of exons 1a, 1b, and 2 in an African American family.
Supported by U.S. Army grant DAMD17-01-1-0266.
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