LYRM7-associated mitochondrial complex III deficiency presenting as infantile hemiparesis with chronic cerebral infarction: a case report

Abstract

Mitochondrial oxidative phosphorylation (OXPHOS) disorders are rare genetic diseases that primarily affect organs with high energy demands, especially the brain. Although stroke-like episodes are recognised manifestations, presentation as chronic cerebral infarction in infancy is uncommon. Variants in the LYRM7 gene causing mitochondrial complex III deficiency are extremely rare. We report an infant who presented with an acute-onset right-sided hemiparesis following a febrile illness and was found to have a chronic left middle cerebral artery territory cerebral infarction on neuroimaging. The child had delayed developmental milestones, elevated serum lactate, and magnetic resonance spectroscopy findings suggestive of mitochondrial dysfunction. Whole-exome sequencing identified a pathogenic homozygous variant in the LYRM7 gene, confirming mitochondrial complex III deficiency. Supportive management and multidisciplinary rehabilitation resulted in gradual improvement in motor function and developmental progress in follow-up. This case broadens the phenotypic spectrum of LYRM7-associated mitochondrial disease by presenting an unusual case. Recognition of mitochondrial disorders in infants presenting with stroke-like neurological deficits is essential for timely genetic diagnosis, appropriate management, family counselling, and long-term follow-up.