Fatal infantile lactic acidosis and a novel homozygous mutation in the SUCLG1 gene: a mitochondrial DNA depletion disorder

Mitochondrial DNA (mtDNA) depletion syndromes are autosomal recessive conditions in which the mtDNA copy number is greatly decreased in affected tissues. The encephalomyopathic group of these syndromes comprise mutations in SUCLA2 and SUCLG1 subunits [1]. In this report, we describe a patient with fatal infantile lactic acidosis associated with mutations in the SUCLG1 gene and mtDNA depletion. Histological and enzymatic abnormalities in skeletal muscle support the diagnosis of this recently described mitochondrial disorder. This case is unique in that prenatal imaging suggested the diagnosis and that the confirmatory molecular diagnosis was established at 2 weeks of age. We describe prenatal MRI and neonatal laboratory disturbances that can point the clinician toward consideration of this diagnosis when treating infantile lactic acidosis.