Summary
Both factor V Leiden and the C677T methylenetetrahydrofolate reductase (MTHFR) gene
mutation are associated with premature vascular disease, and yet are found at surprisingly
high allele frequencies in European populations, 2.7% and 35% respectively. We have
investigated the prevalence of these mutations in 87 UK residents over the age of
ninety, to look for any evidence of their association with premature death.
Five factor V Leiden heterozygotes were found, giving an allele frequency of 2.9%,
similar to that in the general UK population. The frequency of the thermolabile C677T
MTHFR mutation was 36% with 11% homozygotes, again similar to that in the UK population;
these genotypes are in Hardy-Weinberg equilibrium, suggesting that there is not strong
selection against the homozygous state. One person was both heterozygous for factor
V Leiden and homozygous for the C677T mutation. This study suggests that neither factor
V Leiden nor thermolabile MTHFR are risk factors for premature death.