Diabetes is a common manifestation in mitochondrial diseases caused by mutations in mtDNA. The most important mutation is the m.3243A>G substitution in the MTTL1 gene, which leads to hearing loss and diabetes at a young age. Diabetes resembles type 2 diabetes. Impaired insulin secretion is a typical finding. Typically, mitochondrial diabetes is associated with normal weight and the disease is diagnosed between 20 and 45 years of age. In an unselected sample, the prevalence of mitochondrial diabetes is less than 1%, but around 2 to 2.5% if diabetes is inherited from the maternal side.
Mitochondrial diabetes should be particularly suspected in adults having both diabetes and hearing impairment. The prevalence of the mutation m.3243A>G can be up to 60% in these subjects. The level of heteroplasmy of the mutation in the blood sample is often low, and the mutation cannot always be demonstrated in the DNA. In these cases the mutation is found in other tissues, e.g. skeletal muscle.
The analysis is performed from a whole blood sample (EDTA). Instructions for storage and sending the sample as well as prices for DNA screening are given in the request form. The report and interpretation of the results are mailed to the address given in the order 6-8 weeks after the arrival of the blood sample.