The C677T variant is a common genetic polymorphism found in the MTHFR gene, characterized by a specific change in the DNA sequence that leads to an altered protein.
Understanding the MTHFR C677T Variant
The C677T variant is formally known as the MTHFR C677T polymorphism. This particular genetic variation occurs within the methylenetetrahydrofolate reductase (MTHFR) gene. The MTHFR enzyme is essential for processing folate, a B vitamin vital for many bodily functions, including DNA synthesis and repair.
Genetic Change and Protein Impact
The "C677T" designation precisely describes the nature of this genetic change:
- Single Nucleotide Polymorphism (SNP): It indicates that at position 677 in the MTHFR gene, the DNA base cytosine (C) is replaced by thymine (T). This is a single point mutation in the genetic code.
- Amino Acid Substitution: This specific DNA change has a direct consequence on the protein produced. The C677T polymorphism results in an alanine-to-valine substitution in the MTHFR enzyme. This amino acid change can affect the enzyme's stability and activity.
Prevalence and Demographics
The C677T variant is widely distributed globally and is considered a common genetic variation:
- General North American Population: It exhibits a notable allele frequency of approximately 35%.
- Specific Population Groups: This variant is frequently observed among Caucasian and Asian populations.
- Homozygous Individuals: In these populations, the rate of individuals who are homozygous for the T allele (meaning they have inherited two copies of the variant) typically ranges from 12% to 15%.
To summarize the key characteristics of the C677T variant:
| Characteristic | Description |
|---|---|
| Gene Affected | MTHFR (methylenetetrahydrofolate reductase) |
| Type of Change | Single Nucleotide Polymorphism (SNP) |
| DNA Change | Cytosine (C) replaced by Thymine (T) at position 677 |
| Protein Change | Alanine substituted by Valine |
| Allele Frequency | ~35% in general North American population |
| Prevalence | Common in Caucasian and Asian populations |
| Homozygous Rate | ~12-15% in Caucasian and Asian populations for homozygous individuals |
Understanding such genetic variants provides valuable insights for genetic research and personalized health discussions. For more detailed information on the MTHFR gene and its functions, you can explore reputable genetic databases such as NCBI Gene.
