Hepatoencephalopathy due to combined oxidative phosphorylation defect type 1

Hepatoencephalopathy due to combined oxidative phosphorylation defect type 1 (also known as combined oxidative phosphorylation deficiency 1, or COXPD1) is an extremely rare and severe mitochondrial disorder caused by mutations in the GFM1 gene, which encodes mitochondrial translation elongation factor G1. This protein is essential for the translation of mitochondrial DNA-encoded proteins that form critical subunits of the oxidative phosphorylation (OXPHOS) complexes. When GFM1 is deficient, multiple OXPHOS complexes are impaired, leading to a combined deficiency of mitochondrial energy production that predominantly affects the liver and brain. The disease typically presents in the neonatal or early infantile period with progressive hepatic failure (liver dysfunction) and severe encephalopathy (brain dysfunction). Key clinical features include lactic acidosis, hypotonia (reduced muscle tone), developmental delay or regression, seizures, liver enlargement (hepatomegaly), elevated liver enzymes, and feeding difficulties. Some patients may also develop microcephaly and respiratory failure. The course is generally severe and progressive, with many affected infants experiencing rapid neurological deterioration. There is currently no curative treatment for this condition. Management is supportive and symptomatic, focusing on nutritional support, seizure management, and treatment of metabolic crises including lactic acidosis. Liver transplantation has been considered in some cases but does not address the neurological component of the disease. The prognosis is generally poor, with many affected children succumbing to the disease in infancy or early childhood.

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