Mild hyperhomocysteinaemia is a major risk factor for vascular disease and neural tube defects (NTDs), conferring an approximately three-fold relative risk for each condition. It has several possible causes: heterozygosity for rare loss of function mutations in the genes for 5,10-methylene tetrahydrofolate reductase (MTHFR) or cystathionine-beta-synthase (CBS); dietary insufficiency of vitamin co-factors B6, B12 or folates; or homozygosity for a common 'thermolabile' mutation in the MTHFR gene which has also been associated with vascular disease and NTDs. We quantified the contribution of the thermolabile mutation to the hyperhomocysteinaemic phenotype in a working male population (625 individuals). Serum folate and vitamin B12 concentrations were also measured and their relationship with homocysteine status and MTHFR genotype assessed. The homozygous thermolabile genotype occurred in 48.4, 35.5, and 23.4% of the top 5, 10, and 20% of individuals (respectively) ranked by plasma homocysteine levels, compared with a frequency of 11.5% in the study population as a whole, establishing that the mutation is a major determinant of homocysteine levels at the upper end of the range. Serum folate concentrations also varied with genotype, being lowest in thermolabile homozygotes. The MTHFR thermolabile genotype should be considered when population studies are designed to determine the effective homocysteine-lowering dose of dietary folate supplements, and when prophylactic doses of folate are recommended for individuals.

This study demonstrated a high prevalence of infection in a population from a developed country. Previously reported associations between H. pylori infection, age, sex, social class, and reduced height in females were confirmed and smoking was identified as a possible risk factor for H. pylori infection.

Objective-To determine whether Helicobacter pylori infection is associated with the development of ischaemic heart disease and whether such infection can explain the social class inequality in ischaemic heart disease. Design-Cardiovascular risk factor levels, prevalence of ischaemic heart disease (Rose questionnaire angina, and/or a history of myocardial infarction), and serum antibodies to H pylori (enzyme linked immunosorbent assay) were assessed in a cross sectional population based survey. (CI)

Socio-economic differentials in long-term risk of CHD are apparent in both cohorts of men from France and Northern Ireland, particularly in men with evidence of CHD at baseline. Among men free of CHD at baseline, although there is strong evidence of socio-economic differentials in cardiovascular risk factors these do not contribute independently to risk of CHD at 5 years of follow-up in this large cohort of men from France and Northern Ireland.