The MTHFR C677T and A1298C mutations are common genetic variations that occur in the MTHFR gene. The MTHFR C677T mutation occurs in about 10-15% of the population, and the MTHFR A1298C mutation occurs in about 30-35% of the population.
The combined presence of both mutations (compound heterozygous) is less common, and the prevalence varies depending on the population. It is estimated that around 2-5% of the population may be compound heterozygous for the C677T and A1298C mutations.
It's important to note that the prevalence of these mutations can vary depending on the population, and in some populations, the frequency may be higher or lower. Additionally, the risk of developing health problems associated with these mutations can vary depending on other genetic and environmental factors, and not everyone with the mutations will develop related health issues.
It's important to consult with a genetic counselor or healthcare provider to determine the prevalence of the mutation in specific population and also to evaluate the potential implications of the mutations on health outcomes.