These factors include. 1  Living at high latitudes (closer to the polar regions), particularly during winter months. 2  Air quality conditions: high levels of air pollution. 3  Weather conditions: dense cloud covering. 4  The degree to which clothing covers the skin. 5  Use of sunscreen. 6  Skin pigmentation: darker skin types.
A few cases of severe homocysteinemia have been due to rare MTHFR gene mutations (sometimes in combination with a second common MTHFR gene mutation). Symptoms in these patients varied greatly but often involved pronounced neurological symptoms and blood vessel disease.
MTHFR mutations are common. The mutations can be âheterozygousâ meaning they occur only on one strand or âalleleâ of the chromosome, or they can be âhomozygousâ, occurring on both alleles. The frequency of a heterozygous C677T mutation is common, occurring in about 35% of the population.n abnormal change in gene structure, called a mutation, of the MTHFR gene can cause a disruption of the MTHFR enzymeâs normal function of breaking down homocysteine.