EPIYA motiefs of cagA and upper gastrointestinal diseases.

To the Editor

In the April issue, Gastroenterology and Hepatology From Bed to Bench published a paper that focuses on the prevalence of EPIYA motiefs of cagA in Iranian patients and correlation with gastrointestinal disorders. Recently published research indicates that 56% of H. pylori isolated from Iranian patients carry cagA(1). It is not surprising that many H. pylori strains are cagA negative, but it should be noticed that the role of cagA in gastrointestinal cancers is still unclear. One of the first studies about EPIYA motifes is done by Shokrzadeh et al (2). Their study screened 190 patients, among them 141 patients (74.2%) were proven to be infected with H. pylori and 92 (73.6%) were positive for the cagA gene. To analyze the 3′-end variable region of the cagA gene in H. pylori isolated from Iranian population, they performed nucleotide sequencing of the cagA variable regions. Shokrzadeh et al. reported that 3' region of the cagA gene in Iranian strains is Western type. Although they had more samples of cagA positive H. pylori strains in comparison to that of the current study, they could not find any significant differences between EPIYA types and clinical outcomes. While the new research claim that the correlation between the presence of H. pylori EPIYA cagA motifs in the upper gastrointestinal diseases and clinical outcomes. Another study by our team (3) had similar results and could not find an association between the cagA status and clinical outcomes such as cancers in Iranian patients, which was in agreement with other studies in Iran (4, 5, 6,7). One more point that should be considered is about the western type of cagA EPIYA repeats or East Asian type repeats. The cagA gene is reported to be sub-typed based on the number of sequences of the repeat region in the 3′ region of the cagA gene (8, 9), and the cagA gene with multiple repeats and/or East Asian type repeats are reported to be more virulent than with fewer repeats and/or Western type repeats (8, 10). Another interesting point is about the prevalence of cagA, in published studies. The results showed that the prevalence of cagA-positive H. pylori in Shiraz is as high as in western countries. However, according to Baghaei et al. study we can add at this point that the reported prevalence is also similar to the eastern countries. Baghaei K et al, reported that among 231 H.pylori-positive patients, 154 (66.7%) patients were infected with the cagA-positive strains that is similar to the current studies and other countries such as Colombia, Cuba, china and neighbors of Iran, such as Turkey, Saudi and Iraq.

Regarding the fact that Iranian cagA motiefs are western type, they cannot be really in related with severe gastrointestinal disorders like cancers. So it does not seem to be a reliable conclusion because of low samples size. However our previous studies with more cagA positive strains did not find any correlation between cagA repeats and cancer. Therefore, further studies will be necessary to investigate whether the cagA sub-typing is involved in the development of clinical outcomes among the Iranian population.