Hepatomioneuropathy secondary to mitochondrial DNA depletion

INTRODUCTION: Mitochondrial DNA depletion (mtDNA) is an highly heterogeneous condition characterized by a decreased number of mtDNA copies. CASE REPORT: The patient is a 22-month-old girl with generalized hypotonia, marked weakness, respiratory failure, arterial hypertension, hyperlactacidemia, hepatosplenomegaly and mild hypertransaminasemia without hepatic failure neither hypoketotic hypoglycemia. Electromyographic findings were consistent with neuromyopathy and muscle biopsy suggested a neurogenic atrophy. Electron microscopy revealed lipid droplets, subsarcolemmal accumulation of mitochondrias and glycogen granules. Respiratory chain enzime activities were normal. Genetic study in muscle showed mtDNA depletion, and the diagnosis of spinal muscular atrophy caused by survival motoneuron gene deletion was excluded. CONCLUSIONS: This case might be a novel phenotype of mtDNA depletion which could be named hepatomioneuropatyc form. A normal result of respiratory chain enzimes in muscle doesn't excluded mtDNA depletion.