A Patient with a Family History of Breast Cancer, in Which

A patient with a family history of breast cancer, in which several affected relatives have a known mutation in the BRCA1 gene, is screened for the presence of the mutation by allele-specific oligomer hybridization. Signal from the labeled oligomer corresponding to the normal sequence was observed when exposed to the patient's sample. Signal was also observed when the labeled oligomer of the mutant sequence was tested with the patient's sample. Which of the following corresponds to the correct interpretation of these results?

A) The patient has a normal BRCA1 sequence.
B) The patient has a heterozygous mutation in BRCA1.
C) The patient has a homozygous mutation in BRCA1.
D) The results are not valid.