Propionic acidemia is an inherited condition in which the body can't breakdown certain parts of proteins and fats. This leads to a build-up of toxic substances and to bouts of serious illness called decompensation events or metabolic crises. Symptoms of a decompensation event include poor feeding, vomiting, weak muscle tone (hypotonia), and lack of energy (lethargy). Without early diagnosis and treatment, these symptoms may lead to more serious medical problems, including heart abnormalities, seizures, intellectual disability, coma, and possibly death. Propionic acidemia is caused by changes in the PCCA and PCCB genes and is inherited in an autosomal recessive pattern. Diagnosis is based on the symptoms, clinical exam, blood and urine testing, and may be confirmed by the results of genetic testing.