Combined oxidative phosphorylation defect type 7

Combined oxidative phosphorylation deficiency type 7 (COXPD7) is an extremely rare autosomal recessive mitochondrial disorder caused by mutations in the MTRFR gene (also known as C12orf65), which encodes a mitochondrial translation release factor involved in the termination of mitochondrial protein synthesis. Because oxidative phosphorylation (OXPHOS) is essential for cellular energy production, defects in this pathway lead to impaired function of multiple organ systems that have high energy demands, particularly the nervous system and eyes. The condition typically presents in childhood and is characterized by a combination of neurological and ophthalmological features. Key clinical manifestations include optic atrophy leading to progressive visual impairment, peripheral neuropathy (particularly a Charcot-Marie-Tooth-like sensorimotor neuropathy), spastic paraparesis, and progressive encephalopathy. Patients may also develop leukoencephalopathy, cognitive decline, and growth retardation. Lactic acidosis, a hallmark of mitochondrial energy metabolism defects, may be present. The severity and combination of symptoms can vary among affected individuals, even within the same family. There is currently no cure or disease-specific treatment for COXPD7. Management is supportive and symptomatic, focusing on neurological rehabilitation, visual aids, physical therapy for motor impairments, and monitoring for metabolic decompensation. Supplementation with cofactors such as coenzyme Q10 and riboflavin may be tried empirically, though evidence for their efficacy in this specific condition is limited. Genetic counseling is recommended for affected families.

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