PIK3CA mutations in breast cancer: A Tunisian series

BACKGROUND

The aim of this study was to analyze PIK3CA mutations in exons 9 and 20 in breast cancers (BCs) and their association with clinicopathological characteristics.

METHODS

Mutational analysis of PIK3CA exon 9 and 20 was performed by Sanger sequencing in 54 primary BCs of Tunisian women. The associations of PIK3CA mutations with clinicopathological characteristics were analyzed.

RESULTS

Fifteen exon 9 and exon 20 PIK3CA variants were identified in 33/54 cases (61%). PIK3CA mutations including pathogenic (class 5/Tier I) or likely pathogenic (class 4/Tier II) occurred in 24/54 cases (44%): 17/24 cases (71%) in exon 9, 5/24 cases (21%) in exon 20 and 2/24 cases (8%) in both exons. Of these 24 cases, 18 (75%) carried at least one of the three hot spot mutations: E545K (in 8 cases), H1047R (in 4 cases), E542K (in 3 cases), E545K/E542K (in one case), E545K/H1047R (in one case) and P539R/H1047R (in one case). Pathogenic PIK3CA mutations were associated with negative lymph node status (p = 0.027). Age distribution, histological SBR tumor grading, estrogen and progesterone receptors, human epidermal growth factor receptor 2, and molecular classification were not correlated with PIK3CA mutations (p > 0.05).

CONCLUSION

The frequency of somatic PIK3CA mutations in BCs of Tunisian women is slightly higher than that of BCs of Caucasian women and more observed in exon 9 than in exon 20. PIK3CA mutated status is associated with negative lymph node status. These data need to be confirmed in larger series.

HLA antigens and idiopathic epilepsy

Fifty-two mentally normal Egyptian children with idiopathic epilepsy were human leukocyte antigen (HLA) typed. They were divided into two subgroups: generalized tonic-clonic seizures (36 cases) and absences (16 cases). When the frequencies of HLA antigens were compared statistically with those of 120 normal controls, HLA-A9 was found to be significantly higher in the total epilepsy group and the two subgroups. This finding, together with the low HLA-A9 gene frequency in our group of normal Egyptians as compared with other ethnic populations, strongly suggests an association between antigen A9 and one or more of the polygenes controlling the development of idiopathic epilepsy. The relative risk indicated that persons having antigen A9 are 16 times more susceptible to epilepsy than persons lacking it.