To ask Her Majesty’s Government, further to the Written Answer by Earl Howe on 6 January (HL3839), whether they can provide any extant examples of a "gene therapy" that does not modify any genes, of a "germ line therapy" that does not affect the germ line, or of a "germ line gene therapy" that does not affect any genes to be transmitted through the germ line; if not, what is the basis of their assertion that a "germ line gene therapy" does not constitute genetic modification; how discussion is clarified by defining genetic modification such that it "is not that that is what it is"; and whether they will place in the Library of the House copies of any written contributions towards the development of the working definition by the Department for Business, Innovation and Skills, the Wellcome Trust and the Nuffield Council on Bioethics.
The working definition adopted by the Government for the purpose of taking forward the Mitochondrial Donation regulations states that genetic modification involves the germ-line modification of nuclear DNA (in the chromosomes) that can be passed on to future generations. Mitochondrial donation is not considered to be genetic modification, as the patient’s nuclear DNA remains unaltered during this process. However, the Nuffield Council on Bioethics considered that it can be defined as germ line therapy because the techniques “introduce a change that is incorporated into the (mitochondrial) genes of the resulting people, and so will be incorporated into the germline that they will go on to develop”. Furthermore, because mitochondria are inherited down the maternal line “only women born from these techniques would be able to pass the changes on to their children” and this form of germ line gene therapy does not affect any genes transmitted through the germ line of men born through these techniques.
Cancer gene therapy intended to activate an anti-tumour immune response is an example of gene therapy that does not modify any genes.
The working definition of genetic modification in humans is intended to assist in taking forward the debate on mitochondrial donation.