(BPT) - The third week of September is Mito Awareness Week, a time to recognize mitochondrial diseases. Mitochondrial diseases affect the mitochondria, the structures of the cells that are responsible for making energy. When the mitochondria are not working properly, the body does not have enough energy to carry out its normal functions. This can lead to a variety of health problems that can present at any age and vary in severity. One in 5,000 people have some form of genetic mitochondrial disease. Thymidine kinase 2 deficiency (TK2d) is a debilitating and life-threatening mitochondrial disease that causes progressive and severe muscle weakness.