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.
The MTHFR Gene. There are currently a total of 34 mutations in the MTHFR gene. The MTHFR gene sits on Chromosome 1. There are two key variants we test for (as at this stage there is little or no research on the others). SNPs that we currently test for: MTHFR C677T; MTHFR A1298C; Heterozygous = 1 copy of the gene from either parent Homozygous = 1 copy of the gene from each parent. MTHFR C677T Heterozygous = 40% loss of function * MTHFR C677T Homozygous = 70% loss of function * MTHFR A1298C Heterozygous = 20% loss of function (research not known) MTHFR A1298C Homozygous = 40% loss of function **