SNP arrays are well known for low accuracy when assessing CNVs, compared with other platforms such as bacterial artificial chromosome array and oligonucleotide arrays.25 We therefore attempted to validate CNV regions using Nanostring technology, qPCR and data from the recently published Human CNV Map.7 Twenty-nine predicted CNV loci were selected for validation including the most common deletions (>1% frequency) found to be associated with breast or ovarian cancer risk in the BRCA1 pathogenic variant carrier cohort. This evidence concerns the gene BRCA1 and ovarian cancer.