What are the signs and symptoms of Methylmalonic acidemia with homocystinuria, type cblC? For both methylmalonic acidemia and methylmalonic acidemia with homocystinuria (MMA+HCU) cblC type signs and symptoms can vary from mild to life-threatening. There have been cases of MMA+HCU cblC type associated with mild symptoms and delayed age at onset (teen to adult years). In most cases however, signs and symptoms of MMA+HCU cblC type present in infancy. Even with early diagnosis and treatment, children with the condition tend to have symptoms affecting vision, growth, and learning. A recent study of 12 children with early onset MMA+HCU CblC type, diagnosed by newborn screening, and treated early with intramuscular hydroxocobalamin, oral betaine, folinic acid, l-carnitine, and dietary protein modification were reported to have developed the following symptoms: Mild to moderate low muscle tone (91%) Quick uncontrollable movements of the eye (nystagmus) with variable affect on vision (75%) Seizure (25%) Small head circumference (17%) Testing of communication, socialization, daily living skills, motor skills, and behavior showed mild to moderate delays in these areas for most children. Socialization was the least affected aspect of development. The Human Phenotype Ontology provides the following list of signs and symptoms for Methylmalonic acidemia with homocystinuria, type cblC. 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) Anorexia 90% Hydrocephalus 90% Megaloblastic anemia 90% Microcephaly 90% Pallor 90% Reduced consciousness/confusion 90% Retinopathy 90% Seizures 90% Infantile onset 50% Abnormality of extrapyramidal motor function - Autosomal recessive inheritance - Cerebral cortical atrophy - Confusion - Cystathioninemia - Cystathioninuria - Decreased adenosylcobalamin - Decreased methionine synthase activity - Decreased methylcobalamin - Decreased methylmalonyl-CoA mutase activity - Dementia - Failure to thrive - Feeding difficulties in infancy - Hematuria - Hemolytic-uremic syndrome - High forehead - Homocystinuria - Hyperhomocystinemia - Hypomethioninemia - Intellectual disability - Lethargy - Long face - Low-set ears - Macrotia - Metabolic acidosis - Methylmalonic acidemia - Methylmalonic aciduria - Muscular hypotonia - Nephropathy - Neutropenia - Nystagmus - Pigmentary retinopathy - Proteinuria - Reduced visual acuity - Renal insufficiency - Smooth philtrum - Thrombocytopenia - Thromboembolism - Tremor - Visual impairment - 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.