Helicobacter pyloriand gastric cancer in the Middle East: A new enigma?

Abstract

The Middle East is the home of ethnic groups from three main backgrounds: Semitic (Arabs and Jews), Indo-European (Persians and Kurdish) and Turkic (Turkish and Turkmens). Its geographic location, which has been under continuous influences from Asia, Europe and Africa, has made it an ideal site for epidemiological studies on Helicobacter pylori (H. pylori) infection and genotyping. The gastric cancer rate differs in this region from very high in Iran (26.1/10(5)) to low in Israel (12.5/10(5)) and very low in Egypt (3.4/10(5)). Epidemiological studies showed that the prevalence of H. pylori is almost similar in those countries with a high level of infection in childhood. Importantly, the frequency of vacA s1 and m1 regions and cagA+ genotypes were higher in non Semitic populations who inhabit the North than Semitic populations, the inhabitants of Southern parts of the Middle East. H. pylori infection prevalence, distribution pattern of virulence factors, diet and smoking could not have explained the difference in cancer rate. This reflects the multifactorial aetiology of gastric cancer and suggests that H. pylori infection does not always directly correlate with the risk for gastrointestinal disease, such as gastric cancer. Further detailed investigations and international comparative studies of each risk factor need to be performed to investigate whether this represents a true enigma.

Helicobacter pylori genotypes among patients in a university hospital in Egypt: identifying the determinants of disease severity

“…A similar finding has also been concluded from eastern Asia 26 , Iraq and Iran. 19 Nearly equal distribution of vacAm1 and vacAm2 alleles was encountered in this study. The same has been found in Jordan 27 .…”

INVESTIGATION OF Helicobacter pylori VIRULENCE GENOTYPE IN GASTRIC BIOPSIES BY PCR

“…The strains in the present study belong to western type, as studies indicated s1b subtype is rarely found in East-Asian countries [29,32,38]. Our results revealed m2 as the main allele that similar to studies from Iraq, Turkey, Iran, Saudi Arabia, and the middle east region characterized m2 as the main allele [14,32,33,[39][40][41][42]. In another hand, some studies reported that the predominant vacA m subtype was m2 and no association or no role between vacA m genotypes and the development of peptic ulcer [2,32,33,42,43], whereas other studies had been found that vacA m1 strains are associated with high levels of inflammation in the gastric mucosa and increased the risk of gastric atrophy and carcinoma [2,44].…”

Helicobacter pylori vacA genotyping in relation to cagA status, ultra-structure of gastric mucosa and clinical outcomes in Egyptian patients

“…The m-region encodes the vacA binding site to host cells, which appears to be more effective in the m1 than in m2 forms (Ferreira et al, 2014). Similar to previous studies in Turkey, Iraq, Iran, Saudi Arabia (Hussein, 2010) and China (Chung et al, 2010), m2 was predominantly found in all studied H. pylori strains (70%) previously reported. However, this was inconsistent with previous results obtained from Egypt where equal distribution of vacA m1 and m2 was found (Amer et al, 2013).…”