Propionic acidemia (PA) is a rare autosomal recessive organic aciduria resulting from defects in propionyl-CoA-carboxylase (PCC), a key enzyme of intermediate energy metabolism. PA mostly manifests during the neonatal period, when affected newborns develop severe metabolic acidosis and hyperammonemia. We present a previously healthy teenager, who suffered from acute fatigue and breathlessness. The patient was tachycardic, displayed a precordial heave and a systolic murmur. Cardiac investigations revealed severe dilated cardiomyopathy (DCM). Biochemical work up led to the diagnosis of PA. Remarkably, this patient of consanguineous Hispanic origin was in a good general health condition before the acute onset of DCM. Diagnosis of PA was confirmed by enzymatic and molecular genetic analysis, the latter revealing a novel homozygous mutation in the PCCB gene (c.1229G > A; p.R410Q). Residual PCC enzyme activity of approximately 14 % of normal was detected in patient's lymphocytes and fibroblasts, thereby providing a possible explanation for the hitherto asymptomatic phenotype.
Conclusion: Isolated DCM, although rare, can be the leading and/or sole symptom of late-onset PA. Therefore, patients with DCM should receive a comprehensive diagnostic evaluation including selective screening for inborn errors of metabolism.