MRPS34 is a mitochondria-specific ribosomal protein essential for mitochondrial translation and mitoribosme assembly. It is required for stability of the small ribosomal subunit and the 12S rRNA 1. MRPS34 mutations compromise synthesis of all 13 mitochondrially-encoded polypeptides, reducing levels of mitochondrial respiratory complexes and decreasing oxygen consumption and respiratory chain enzyme activity 12. The protein may be trafficked to mitochondria through interactions with scaffolding proteins prior to mitochondrial entry 3. Pathogenic biallelic MRPS34 mutations cause Combined Oxidative Phosphorylation Deficiency 32 (COXPD32), typically presenting in infancy with developmental delay, feeding difficulties, lactic acidosis, and neurological manifestations including dystonia and ocular symptoms 4. Brain MRI characteristically shows symmetrical abnormal signals in the brainstem, thalamus, and basal ganglia 4. Recently, MRPS34 variants have been identified in adult-onset leukoencephalopathy with cerebellar ataxia, motor neuropathy, and profound cerebral folate deficiency, where folinic acid treatment induced clinical stabilization 5. Disease severity ranges from developmental delay with childhood survival to severe presentations with respiratory and circulatory failure 4. The underlying mechanism involves impaired small mitoribosomal subunit assembly and destabilization of actively translating ribosomes, leading to reduced OXPHOS enzyme activity across multiple tissues 12.