No.
Micro-array analysis (as opposed to the Exome sequencing they are starting to offer, which may be useful for BRCA diagnosis) focusses on frequently occurring single nucleotide polymorphisms (substitution of one base for another). The majority of these are benign.
By looking at lots of commonly occurring variants it is hoped that they can map regions of the genome that may harbour other mutations that may actually have an effect.
Baynes et al., 2007 [1] showed that none of the commonly occurring SNP's in BRCA (> 1-5% of the population) have a significant risk in cancer.