Cardiomyopathy of unknown etiology: Barth syndrome unrecognized.

This is a report of a child who died at 20 months from what was clinically thought to be cardiomyopathy of unknown etiology. Barth syndrome, an X-linked mitochondrial cardioskeletal myopathy, was diagnosed by genetic testing at autopsy. Barth syndrome presents in infancy or childhood with cardiomyopathy, hypotonia, growth delays, and cyclic neutropenia. Other associated laboratory findings can include hypocholesterolemia, relative monocytosis, low prealbumin, low plasma carnitine, and lactic acidosis. The classic echocardiogram finding is left ventricular noncompaction, although not always present. Until recently, the most reliable biochemical finding has been 3-methylglutaconic aciduria. However, quantitative analysis must be specifically requested for results to be reliable. Recently, a confirmatory tetralinoleoyl cardiolipin high-pressure liquid chromotography-tandem mass spectrometry blood test has become available. Genetic testing is also confirmatory and details the underlying mutation. Diagnosis is often missed or delayed and early diagnosis improves survival. The purpose of this case report is to encourage physicians to include Barth syndrome in the differential for cardiomyopathy of uncertain etiology in males, especially in the presence of growth delays, hypotonia, neutropenia, and/or family history of pediatric male death of unknown etiology.