Myopathic form The TK2 related myopathic form results in muscle weakness, rapidly progresses, leading to respiratory failure and death within a few years of onset. The most common cause of death is pulmonary infection. Only a few people have survived to late childhood and adolescence. Encephalomyopathic form SUCLA2 and RRM2B related forms result in deformities to the brain. A 2007 study based on 12 cases from the Faroe Islands (where there is a relatively high incidence due to a founder effect) suggested that the outcome is often poor with early lethality. More recent studies (2015) with 50 people with SUCLA2 mutations, with range of 16 different mutations, show a high variability in outcomes with a number of people surviving into adulthood (median survival was 20 years. There is significant evidence (p = 0.020) that people with missense mutations have longer survival rates, which might mean that some of the resulting protein has some residual enzyme activity. RRM2B mutations have been reported in 16 infants with severe encephalomyopathic<unk>  that is associated with early-onset (neonatal or infantile), multi-organ presentation, and mortality during infancy. Hepatopathic form DGUOK, POLG, and MPV17 related forms result in defects to the liver. Liver dysfunction is progressive in the majority of individuals with both forms of DGUOK-related<unk>  and is the most common cause of death. For children with the multi-organ form, liver transplantation provides no survival benefit. Liver disease typically progresses to liver failure in affected children with MPV17-related<unk>  and liver transplantation remains the only treatment option for liver failure. Approximately half of affected children reported did not undergo liver transplantation and died because of progressive liver failure – the majority during infancy or early childhood. A few children were reported to survive without liver transplantation.
Mitochondrial DNA depletion syndrome
Mitochondrial disease
Glutaminase deficiency
Pyruvate kinase deficiency
Pyruvate dehydrogenase deficiency
3-Methylcrotonyl-CoA carboxylase deficiency
Succinyl-CoA:3-oxoacid CoA transferase deficiency
Contiguous gene syndrome