Executive summary Mitochondria are small structures present in human cells that produce a cell‟s energy. They contain a small amount of DNA that is inherited exclusively from the mother through the mitochondria present in her eggs. Mutations in this mitochondrial DNA can cause a range of rare but serious diseases, which can be fatal. However, there are several novel methods with the potential to reduce the transmission of abnormal mitochondrial DNA from a mother to her child, and thus avoid mitochondrial disease in the child and subsequent generations.
The Human Fertilisation and Embryology (HFE) Act 1990 (as amended) only permits eggs and embryos that have not had their nuclear or mitochondrial DNA altered to be used for treatment. However, the Act allows for regulations to be passed by Parliament that will allow techniques that alter the DNA of an egg or embryo to be used in assisted conception, to prevent the transmission of serious mitochondrial disease.
The Secretary of State for Health asked the Human Fertilisation and Embryology Authority (HFEA), in February 2011, to carry out a scientific review to scope “expert views on the effectiveness and safety of mitochondrial transfer”. In order to carry out this task, the HFEA established a small panel, with broad-ranging scientific and clinical expertise, to collate and summarise the current state of expert understanding on the safety and efficacy of methods to avoid mitochondrial disease through assisted conception.
This report presents the panel‟s assessment of the safety and efficacy of the three techniques that have the potential to avoid mitochondrial disease. Preimplantation genetic diagnosis (PGD) involves removing and examining one or more cells from an early embryo to identify those that are unlikely to lead to a mitochondrial disorder in the resulting child. PGD for mitochondrial diseases is licensed in the UK. Maternal spindle transfer and pronuclear transfer are two techniques, currently at the research stage, that involve transferring the mother‟s, or both parent‟s, genetic material into an unfertilised donor egg or a fertilised donor embryo that contains healthy mitochondria. Neither maternal spindle transfer nor pronuclear transfer is permitted for treatment under the HFE Act 1990 (as amended) because each alters the mitochondrial DNA of the egg or embryo.
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