The invention relates generally to a method of treatment for a human genetic disease, such as diseases characterized by unbalanced nucleotide pools, e.g., mitochondrial DNA depletion syndromes, and more specifically, thymidine kinase 2 (TK2) deficiency, using gene therapy. The gene therapy may involve administration of one or more constructs, such as a viral vector, containing a nucleic acid encoding a functional protein. The functional protein may correspond to a nuclear gene. For treatment of TK2 deficiency, the gene therapy may involve administration of one or more constructs, such as a viral vector, containing a nucleic acid encoding a functional TK2 enzyme. The treatment may also involve the administration of pharmacological therapy in conjunction with the gene therapy. The treatment protocols of the disclosure, such as those involving gene therapy alone or in combination with pharmacological therapy, can be used to treat, prevent, and/or cure various other disorders of unbalanced nucleoside pools, especially those found in mitochondrial DNA depletion syndrome.

The invention relates generally to a method of treatment for a human genetic disease, such as diseases characterized by unbalanced nucleotide pools, e.g., mitochondrial DNA depletion syndromes, and more specifically, thymidine kinase 2 (TK2) deficiency, using gene therapy. The gene therapy may involve administration of one or more constructs, such as a viral vector, containing a nucleic acid encoding a functional protein. The functional protein may correspond to a nuclear gene. For treatment of TK2 deficiency, the gene therapy may involve administration of one or more constructs, such as a viral vector, containing a nucleic acid encoding a functional TK2 enzyme. The treatment may also involve the administration of pharmacological therapy in conjunction with the gene therapy. The treatment protocols of the disclosure, such as those involving gene therapy alone or in combination with pharmacological therapy, can be used to treat, prevent, and/or cure various other disorders of unbalanced nucleoside pools, especially those found in mitochondrial DNA depletion syndrome.