Abstract
We present a patient with ataxia, retinitis pigmentosa, dysarthria, neurosensorial deafness, nystagmus and leukoencephalopathy. A novel heteroplasmic G to A transition at nucleotide 15 975 was found, affecting the T arm of the mitochondrial (mt) tRNA(Pro) gene. A biochemical analysis of respiratory chain enzymes in muscle revealed isolated complex I deficiency. This is the fourth pathogenic tRNA(Pro) point mutation to be associated with an mt disorder. The result highlights the importance of molecular dissection of mtDNA in patients with defined mt disorder and confirms the clinical and biochemical heterogeneity associated with tRNA(Pro) mutations.