A novel PIK3CA hotspot mutation in Isfahanian breast cancer patients.

Somatic mutations of phosphatidylinositol 3-kinase (PI3K) catalytic subunit (PIK3CA) play an important role in tumorigenesis. Using PCR-SSCP, followed by sequencing, we examined the PIK3CA gene over the previously identified mutational hotspots in a panel of 50 breast cancer and 5 normal breast tissue, as well as 50 normal blood samples isolated from a population of Iranian patients. In the present study, the frequency of PIK3CA mutation was 14%. However, the previously identified hotspot mutations in exons 20 were completely absent in these breast cancer samples. Instead, we found a new hotspot mutation (3 of 50 samples) in exon 20.