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.
In most cases, symptoms are felt in the calf. Symptoms of intermittent claudication include: 1  Pain, cramping, numbness, or fatigue in the hip, thigh, or calf during activities such as walking or climbing stairs.  Discomfort subsides when activity is discontinued, although it may take a few minutes.