Leucinosis, or maple syrup urine disease (lecture and a clinical case)

Abstract

Maple syrup urine disease (leucinosis, short-chain ketoaciduria, branched-chain disease, branchedchain ketonuria) is an autosomal recessive disorder which is a consequence of the deficient branchedchain alpha ketoacid dehydrogenase complex. There are five subtypes of the disease: classical, intermediate, intermittent, thiamine-dependent and E3-deficient. Leucinosis is characterized by high plasma levels of branched-chain amino acids (leucine, isoleucine and valine) and high urine levels of branched-chain ketoacids, as well as of lactate and pyruvate. Tandem mass spectrometry can be used as a screening method in newborns. Mild disease cannot be identified at screening. The diagnosis should be based on tandem mass spectrometry of a blood sample and aminoacid analysis by gas chromatography of a urine sample. Prenatal diagnosis requires molecular genetic tests. Treatment of maple syrup urine disease is aimed at normalization of plasma branchedchain amino acids levels and includes two main components, namely, life-long diet therapy and active treatment of acute metabolic deterioration episodes. A favorable course of the disease is possible only with early (pre-symptomatic) initiation of treatment. The development of cognitive functions depends on plasma leucine levels. We present a clinical case of delayed diagnosis of leucinosis, despite its early clinical manifestation, leading to irreversible consequences for the patient.