Abstract
The paper discusses the diagnosis and treatment of mitochondrial DNA depletion syndrome (MDS), which is associated with a defect in the thymidine kinase 2 (TK2) gene. Despite the expansion of neonatal screening (up to 36 diseases, with plans to increase it to 62), the detection of MDS requires expensive whole-genome sequencing and is not yet available on a large scale. A case of a girl with TC-2-associated mitochondrial myopathy is described: the disease manifested itself at 9 months with weakness of the limbs and regression of motor skills, complicated by pneumonia, respiratory failure and cardiomyopathy. The diagnosis was confirmed genetically. The patient received therapy with deoxytimidine and deoxycytidine — the condition stabilized, new skills appeared. Long-term follow-up showed a decrease in the frequency of pneumonia, improvement of tests and a decrease in dependence on respiratory support. The importance of early genetic diagnosis and access to treatment is emphasized; research centers and telemedicine can help with this.