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.

Sociocultural and dietary practices among Malay subjects in the north-eastern region of Peninsular Malaysia: a region of low prevalence of Helicobacter pylori infection.

BACKGROUND AND AIM: The prevalence of Helicobacter pylori infection is exceptionally low among the Malays in the north-eastern region of Peninsular Malaysia. The reasons are unknown. Our aim was to compare environmental factors that differed in relation to H. pylori prevalence among Malays born and residing in Kelantan. METHODS: A case-control study was conducted among Malays in Kelantan who underwent upper endoscopy between 2000 and 2008. Helicobacter pylori status was determined by gastric histology. Sociocultural and dietary factors were assessed using a validated investigator-directed questionnaire administered after 2008, and the data were analyzed using logistic regression analysis. RESULTS: The study group consisted of 161 subjects (79 H. pylori positive and 82 controls). Univariable analysis identified five poor sanitary practices associated with an increased prevalence of H. pylori infection: use of well water, use of pit latrine, less frequent boiling of drinking water, and infrequent hand wash practice after toilet use and before meals. Multivariable logistic regression analysis identified three variables inversely associated with H. pylori infection: frequent consumption of tea (OR: 0.023, 95% CI: 0.01-0.07), frequent use of "budu" or local anchovy sauce (OR: 0.09, 95% CI: 0.1-0.7), and frequent use of "pegaga" or centenella asiatica (OR: 0.25, 95% CI: 0.1-0.65). CONCLUSIONS: Under the assumption that sanitary, sociocultural, and dietary habits have not changed over the years, we can conclude that an increased risk of H. pylori was associated with unsanitary practices whereas protection was associated with consumption of tea and locally produced foods, "pegaga" and "budu." These dietary factors are candidates for future study on the effects on H. pylori transmission.

Helicobacter pylori infection among Aborigines (the Orang Asli) in the northeastern region of Peninsular Malaysia.

Whether the exceptionally low prevalence of Helicobacter pylori (HP) infection reported among Malays is also present among aborigines (the Orang Asli) living in northeastern Peninsular Malaysia is unknown. We studied asymptomatic Orang Asli from settlements situated 210 km from the city of Kota Bharu. The HP infection status was confirmed by a validated serology test. Nineteen percent of 480 Orang Asli tested positive for HP infection. The prevalence was 40.6% in the birth cohort of the 1940s and declined steadily in later cohorts to under 10% among 12-30 year olds. This may be related to the phases of relocation from the jungles into resettlement camps and ultimately into designated villages near rivers. The low prevalence pattern after the 1970s was probably partly a result of improvement in sanitation and hygiene practice in these villages but other unidentified factors may also be operating.

Cardiovascular risk factors in pre-pubertal Malays: effects of diabetic parentage.

Diabetes prevalence is increasing rapidly in Asian populations but the influence of a family history of diabetes on cardiovascular risk is unknown. To assess this relationship, 120 urban-dwelling Malays were recruited to a cross-sectional case-control study. Sixty were pre-pubertal children, 30 of diabetic parentage (Group 1) and 30 with no diabetes family history (Group 2). Group 1 and 2 subjects were the offspring of adults with (Group 3) or without (Group 4) type 2 diabetes. Subjects were assessed for clinical and biochemical variables defining cardiovascular risk. Principal component analysis assessed clustering of variables in the children. Group 1 subjects had a higher mean waist:hip ratio, diastolic blood pressure and HbA(1c) than those in Group 2, and a lower HDL:total cholesterol ratio (P<0.03). Although there were no correlations between Group 1 and 3 subjects for cardiovascular risk variables, significant associations were found in Groups 2 and 4, especially HbA(1c) and insulin sensitivity (P< or =0.004). Of five separate clusters of variables (factors) identified amongst the children, the strongest comprised diabetic parentage, HbA(1c), insulin sensitivity and blood pressure. Features of the metabolic syndrome are becoming evident in the young non-obese children of diabetic Malays, suggesting that lifestyle factors merit particular attention in this group.

Prevalence and predictors of Helicobacter pylori infection in children and adults from the Penan ethnic minority of Malaysian Borneo.

To determine the prevalence of Helicobacter pylori antigen carriage in stool in the Penan ethnic minority in Malaysian Borneo, we studied 295 Penans 0.6-89.0 years of age from 1) the remote Limbang Division, 2) Mulu regional center, and 3) Belaga village. Overall, 37.7% of the subjects tested positive. Peak prevalence was reached by 10 years of age. There were no differences in age, sex, body mass index, and socioeconomic/domestic variables between antigen-positive and antigen-negative subjects. In a logistic regression analysis, subjects from Limbang were least likely to be antigen-positive (odds ratio [OR] = 0.23, 95% confidence interval [CI] = 0.12-0.44 versus other sites, P < 0.001). Availability of a flushing toilet was protective against H. pylori carriage (OR = 0.51, 95% CI = 0.27-0.95, P = 0.031). Infection with H. pylori among the Penan was less than reported in other low socioeconomic groups. The lowest prevalence in the most remote setting suggests that the infection has been a recent arrival in previously isolated communities.