A condition that affects how the body breaks down sugar to use as energy in muscle cells. People withthis conditionexperience fatigue, muscle pain, and cramps during exercise (exercise intolerance). In some people,high-intensity exercise or other strenuous activity leads to the breakdown of muscle tissue (rhabdomyolysis), which can lead to myoglobinuria (rust-colored urine indicating breakdown of muscle tissue) and kidney damage. A skin rash may also develop. The severity of the signs and symptoms varies greatly among affected individuals. Lactate dehydrogenase A deficiency is caused by mutations in the LDHA gene. This condition is inherited in an autosomal recessive pattern. The disease is glycogen storage disease due to lactate dehydrogenase M-subunit deficiency (Monarch Disease Ontology id MONDO_0013047). Also known as: GSD due to lactate dehydrogenase M-subunit deficiency, LDH-M subunit deficiency, LDHA glycogen storage disease, glycogen storage disease caused by mutation in LDHA, glycogenosis due to lactate dehydrogenase M-subunit deficiency, lactate dehydrogenase A deficiency.