A three-year-old child exhibits unsteady walking and frequent falls, and experiences leg pain after walking a hundred meters. Examination reveals elevated levels of aspartate aminotransferase and creatine kinase isoenzymes in cardiac enzymes, with the rest of the test results normal. The EMG shows damage to both lower limb nerves, but there is no clear history of trauma. The MRI did not show any abnormalities, and the neurology examination did not yield a definitive diagnosis. What diseases could this be related to?