Patients with methylmalonic acidemia usually have gastrointestinal symptoms, such as diarrhea, bloating, and vomiting. Neonatal patients may experience unexplained crying, hypotonia, muscle weakness, and some patients may suffer from diarrhea and bloating, which may lead to neonatal malnutrition leading to dehydration, or even life-threatening symptoms of coma, atrophy, and acidosis. If children suffer from methylmalonic acidemia, they will experience growth retardation, low mental and physical strength and even regression. There are disorders of consciousness and movement disorders, as well as loss of appetite, which often lead to misdiagnosis and misdiagnosis because of these symptoms. Adult patients often experience problems with the musculo-neurological system, such as dizziness, headaches, hemiparesis, muscle numbness, and involuntary tremors.