Genome-wide association studies in patients with isolated BA have suggested candidate genes and genomic regions (ADD3 and XPNPEP1 in 10q25.1, EFEMP1 in 2p16.1, GPC1 in 2q37.3, ARF6 in 14q21.3) but consistent proof of the involvement of each of these regions has been elusive. This evidence concerns the gene GPC1 and breast angiosarcoma.