Disease Characteristic
One of the most common defects of homocystein is a mutation in the enzyme “5,10-methylene tetrahydrofolate reductase”, which is involved in folate metabolism. Mutations in MTHFR gene are responsible for increase in homocysteine levels in plasma and urine. Increased homocysteine level in plasma is a risk factor for cardiovascular disease and deep-vein thrombosis.

How Common is MTHFR Mutation?
The population frequency of homozygotes ranges from 1% or less among Blacks from Africa and the United States to 20% or more among Whites and US Hispanics.
    
Prevalence
The C677T allele appears to be very common among Hispanics. 21% of Hispanic Whites in a population-based study from California were C677T-homozygous, as were 25% of a convenience sample of Colombians. The frequency of homozygosity among Whites outside of Europe (e.g., in Canada, the United States, Brazil, and Australia) ranged from 10%-14%.

Genes and Mutations (Genotype-Phenotype Relationships)
MTHFR catalyzes the conversion of 5,10-methylenetetrahydrofolate into 5-methyltetrahydrofolate,
which is the major circulating form of folate. Folic acid and MTHFR are involved in  complex biochemical pathways. Mutations in MTHFR enzyme block the conversion of homocystein into methionine.

Mutations and populations
The specific most common mutation, which affects all populations, is conversion of C-to-T at position 677 and A-to-C at position 1298 in MTHFR gene. We investigate for these mutations with diligent accuracy in all affected populations.

Phenotypes                        
Coronary heart disease and stroke
Increased risk of cardiovascular disease
High blood pressure in pregnancy (preeclampsia)

Criteria for Genetic Testing

Increased Homocystein Levels

Vitamin B12 metabolism disorder

Arteriosclerotic vascular disease

Deep vein thrombosis