Question to the Department of Health and Social Care:

To ask Her Majesty’s Government, further to the Written Answers by Earl Howe on 17 November (HL2642) and on 2 December (HL2905), whether they consider that mutations affecting DNA Polymerase Gamma might in turn ever be potentially responsible for disease-associated mitochondrial DNA mutations such as those listed in Annex D of the "Mitochondrial Donation" consultation document; and if not, why not.

We have been advised that there is no evidence to suggest that mutations affecting DNA polymerase gamma result in high levels of the mitochondrial DNA mutations responsible for the mitochondrial diseases listed in Annex D of the mitochondrial donation consultation document. As stated in my previous answer of 17 November 2014 (Official Report, col WA59), mitochondrial donation techniques would only be used for patients that have an inherited mitochondrial DNA mutation and could not be used for those diseases in which faulty mitochondria arise from a nuclear gene mutation.