A multicentre retrospective study evaluated the effects of daily oral administration (treatment lasting on average approximately two years) of deoxycytidine or deoxythymidine (≤ 800 mg/kg/day) in 38 children and adults with thymidine kinase 2 deficiency (TK2d), an ultra-rare mitochondrial myopathy. The investigators compared their clinical progression with data from a control group of 69 patients with similar characteristics reported in the literature. The results show:
- no deaths among treated patients, compared with 58% of controls, representing a 95% reduction in mortality risk;
- recovery of certain motor functions in 65.4% of treated patients;
- a reduction in the time required for ventilatory assistance in 28.6% of them, and discontinuation of feeding tubes in three of the eight patients concerned;
- most adverse events related to taking the treatment were relatively mild. However, two patients had to discontinue treatment after an excessive increase in transaminases.
Although these results are very positive, they will need to be confirmed by further studies to overcome the limitations of an analysis based solely on data from the literature.
