Identification of a 14 kb deletion involving the promoter region of BRCA1 in a breast cancer family.
BRCA1 is a breast and ovarian cancer susceptibility gene. An inferred germline regulatory mutation was previously reported in the BRCA1-linked kindred K2035, based on the absence of transcripts from the BRCA1 allele associated with the cancer susceptibility haplotype. In this study, the promoter region of BRCA1 was examined in individuals from K2035 for evidence of a mutation which could halt transcription. Evaluation of a polymorphism located within intron 2 of BRCA1 gave results consistent with the presence of a large deletion in K2035 mutation carriers. Southern blot analysis identified unique restriction fragments which occurred as a result of a 14 kb deletion that removed both of BRCA1's transcription start sites (exons 1a and 1b) as well as exon 2. Sequencing indicated that unequal crossover between Alu repeats was the likely cause of the deletion. Similar deletions may be responsible for other reported inferred regulatory mutations, as well as unidentified mutations in families linked to BRCA1.
Swensen
J
J
Department of Medical Informatics, University of Utah School of Medicine, Salt Lake City 84108, USA.
Hoffman
M
M
Skolnick
M H
MH
Neuhausen
S L
SL
D000328:Adult; D019313:BRCA1 Protein / Q000235:genetics*; D015139:Blotting, Southern; D001943:Breast Neoplasms / Q000235:genetics*; D003434:Crossing Over, Genetic; D017931:DNA Primers; D015342:DNA Probes; D005260:Female; D016147:Genes, Tumor Suppressor / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007438:Introns / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D017384:Sequence Deletion
D019313:BRCA1 Protein; D017931:DNA Primers; D015342:DNA Probes