Towards understanding the low prevalence of Helicobacter pylori in Malays: genetic variants among Helicobacter pylori-negative ethnic Malays in the north-eastern region of Peninsular Malaysia and Han Chinese and South Indians.

OBJECTIVES: To identify gene polymorphisms that differ between Malays, Han Chinese and South Indians, and to identify candidate genes for the investigation of their role in protecting Malays from Helicobacter pylori (H. pylori) infection. METHODS: Malay participants born and residing in Kelantan with a documented absence of H. pylori infection were studied. Venous blood was used for genotyping using the Affymetrix 50K Xba I kit. CEL files from 141 Han Chinese and 76 South Indians were analyzed to compare their allele frequency with that of the Malays using fixation index (FST ) calculation. The single nucleotide polymorphisms (SNPs) with the highest allele frequency (outliers) were then examined for their functional characteristics using F-SNP software and the Entrez Gene database. RESULTS: In all, 37 Malays were enrolled in the study; of whom 7 were excluded for low genotyping call rates. The average FST estimated from the genome-wide data were 0.038 (Malays in Kelantan vs the South Indians), 0.015 (Malays in Kelantan vs Han Chinese) and 0.066 (Han Chinese vs South Indians), respectively. The outlier gene variants present in Malays with functional characteristics were C7orf10 (FST 0.29988), TSTD2 (FST 0.43278), SMG7 (FST 0.29877) and XPA (FST 0.43393 and 0.43644). CONCLUSION: Genetic variants possibly related to protection against H. pylori infection in ethnic Malays from the north-eastern region of Peninsular Malaysia were identified for testing in subsequent trials among infected and uninfected Malays.

Chronic atrophic antral gastritis and risk of metaplasia and dysplasia in an area with low prevalence of Helicobacter pylori.

INTRODUCTION: The Northeastern region of Peninsular Malaysia is an area with exceptionally low prevalence for Helicobacter pylori infection. The risk of intestinal metaplasia and dysplasia in patients with chronic atrophic gastritis (CAG) and its association with Helicobacter pylori is unknown in this region. METHODS: This was a cross-sectional study on gastric biopsies from 234 consecutive patients (mean age 53.5 [14.8] years) who underwent upper gastrointestinal endoscopy between January 2006 and December 2006. RESULTS: There were 137 (59%) men and 185 (79%) Malay patients. Among 234 biopsies, CAG was found in 99 and non-atrophic gastritis in 135. Intestinal metaplasia and dysplasia were detected in 8 and 6 atrophic gastritis biopsies, respectively, and in 10 and 3 of non-atrophic gastritis biopsies, respectively. H. pylori were detected in 16 (9 Malays, 7 non- Malays) biopsies (p=0.024); intestinal metaplasia was detected in 4 biopsies (p=0.3) and dysplasia in 5 biopsies (p=0.3). Of the 218 biopsies negative for H. pylori, intestinal metaplasia was found in 14 and dysplasia in 4. The risk of intestinal metaplasia as well as dysplasia was associated with presence of H. pylori infection (p=0.029 and p<0.001 respectively). CONCLUSION: Even in a setting of low prevalence of H. pylori, intestinal metaplasia and dysplasia were significantly associated with H. pylori infection. The frequency of intestinal metaplasia and dysplasia was similar different between biopsies with atrophic gastritis and non-atrophic gastritis.