The severity of Charcot-Marie-Tooth Disease (CMT) is increased by the following factors: A family history of CMT. A mutation in the CMT gene. A lack of vitamin B12. A lack of vitamin D. A lack of calcium. A lack of magnesium. A lack of potassium. A lack of folate. A lack of iron. A lack of zinc. A lack of exercise. A lack of sunlight. A lack of vitamin E. A lack of vitamin C. A lack of vitamin B6.