Involvement of mitochondrial dysfunction in pathogenesis of hemophagocytic lymphohistiocytosis

Abstract

Background: Hemophagocytic lymphohistiocytosis (HLH) is a hyper-inflammatory condition resulting from altered crosstalk between innate and adaptive immune responses. Familial HLH is caused by mutations in several genes whereas the acquired form is associated with infections, rheumatic diseases, malignancies, and inherited metabolic disorders. Case Presentation: We report an infant boy who developed HLH and the potential involvement of mitochondrial DNA in pathogenicity. This patient was with evidence of mitochondrial disease based on neonatal-onset lactic acidosis, elevated lactate in cerebrospinal fluid, a significant lactate peak on magnetic resonance spectroscopy, and generalized reduction of multiple respiratory chain enzyme complex activities. In addition, full mitochondrial genome sequencing only revealed the identification of the homoplasmic m.4325A>G mutation. Subsequently, he presented with a febrile illness complicated by HLH. Conclusion: Elevated levels of lactic acidosis and mitochondrial dysfunction strengthen the involvement of mitochondria in causing secondary HLH in our patient.