Question: What is (are) Mitochondrial DNA-associated Leigh syndrome ?
Answer: Mitochondrial DNA-associated Leigh syndrome is a progressive brain disorder that usually appears in infancy or early childhood. Affected children may experience vomiting, seizures, delayed development, muscle weakness, and problems with movement. Heart disease, kidney problems, and difficulty breathing can also occur in people with this disorder. Mitochondrial DNA-associated Leigh syndrome is a subtype of Leigh syndrome and is caused by changes in mitochondrial DNA. Mutations in at least 11 mitochondrial genes have been found to cause mtDNA-associated Leigh syndrome. This condition has an inheritance pattern known as maternal or mitochondrial inheritance. Because mitochondria can be passed from one generation to the next only through egg cells (not through sperm cells), only females pass mitochondrial DNA-associated Leigh syndrome to their children.
Source: GARD

Question: What are the symptoms of Mitochondrial DNA-associated Leigh syndrome ?
Answer: What are the signs and symptoms of Mitochondrial DNA-associated Leigh syndrome? The Human Phenotype Ontology provides the following list of signs and symptoms for Mitochondrial DNA-associated Leigh syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Abnormality of movement 90% Cognitive impairment 90% Incoordination 90% Muscular hypotonia 90% Nystagmus 90% Respiratory insufficiency 90% Strabismus 90% Ophthalmoparesis 50% Optic atrophy 50% Seizures 50% Abnormal pattern of respiration - Ataxia - Autosomal recessive inheritance - CNS demyelination - Dysarthria - Dystonia - Emotional lability - Failure to thrive - Hepatocellular necrosis - Heterogeneous - Hyperreflexia - Hypertrichosis - Increased CSF lactate - Increased serum lactate - Infantile onset - Intellectual disability - Lactic acidosis - Mitochondrial inheritance - Ophthalmoplegia - Phenotypic variability - Pigmentary retinopathy - Progressive - Ptosis - Respiratory failure - Sensorineural hearing impairment - Spasticity - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD