The neurologic outcome of 20 patients with propionic acidemia was evaluated at the Medical Unit, Institute of Child Health, London, England. In 11 patients who presented in the first week of life, the death rate was high and all were mentally retarded (IQ less than 60), and 3 had mild chorea or dystonia. Of 9 patients with onset after the neonatal period, 4 had a severe movement disorder that evolved following an episode of metabolic derangement. In the late onset group, CT disclosed transient basal ganglia lucencies after episodes of metabolic decompensation. CSF neurotransmitter metabolites were unchanged. 
COMMENT. A biotin-responsive propionic acidemia in a newborn is reported from Buenos Aires, Argentina and Paris, France . The infant presented at the 4th day of life with partial feeding rejection, drowsiness, tachypnea, hypothermia and hepatomegaly. He developed generalized tonic-clonic seizures and required mechanical respiratory support. Enzyme studies in fibroblasts showed a profound deficiency of propionyl-CoA carboxylase activity and normal values for pyruvate carboxylase. Lab results showed severe metabolic acidosis and ketonuria. Treatment with carnitine and biotin was followed by clinical improvement and normal urine organic acids. One patient in the early onset group of the London study was treated with biotin and lived to 6 years of age. The outcome for patients with propionic acidemia is generally poor, although there is a wide variation.
Propionic acidemia (ketotic hyperglycinemia) should be distinguished from non-ketotic hyperglycinemia which is characterized by hypotonia, lethargy and seizures beginning on the first day of life. Some infants succumb within a few weeks, whereas others develop mental retardation and extrapyramidal signs.