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Report provided to the Human Fertilisation and Embryology Authority, April 2011 - page 13 / 45





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3.3.4 Rather than aiming specifically at avoiding transmission of the mutation and thus disease prevention, PGD for mitochondrial heteroplasmy can only be aimed at risk reduction.

      • 3.3.5

        Centres that carry out PGD for mtDNA disorders should:

        • offer prenatal diagnosis or PGD as the first option for patients who have an identified mutation and a low to medium level of heteroplasmy

        • have appropriate experience and expertise in the diagnosis and management of mtDNA disorders, knowledge of the different mutations and the proportion of heteroplasmy likely to lead adult disease

        • provide appropriate experienced genetic counselling, in order to decide upon and document the threshold level of abnormal mtDNA measured at PGD above which embryos would not be replaced in order to minimise the risk of the child being affected with the disorder

        • be encouraged to consider single embryo transfer to enable follow up of the fate of the embryo transferred8

        • encourage patients to consider prenatal testing following PGD, to assess the consistency in levels of heteroplasmy

        • record the levels of abnormal mtDNA in the woman, the embryo (trophectoderm or cleavage stage biopsy) and in the subsequent child to assess the degree of correlation


Review of maternal spindle transfer and pronuclear transfer to avoid mitochondrial disease

    • 4.1


      • 4.1.1

        In cases where PGD is not appropriate, such as cases where the woman has high levels of heteroplasmy or is homoplasmic, transmission of mtDNA disease can be

8 Using single embryo transfer will require centres to have an effective cryopreservation programme in order to freeze the remaining suitable embryos that were not transferred. Page 13 of 45

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