London | A new In Vitro Fertilisation (IVF)-based technique is likely to lead to normal pregnancies and reduce the risk that babies born will have mitochondrial disease, scientists have found.
Scientists at the Wellcome Trust Centre for Mitochondrial Disease at Newcastle University in the UK conducted the first in-depth analysis of human embryos created using a new technique designed to reduce the risk of mothers passing on a debilitating, life-limiting mitochondrial disease to their children.
The new technique, called ‘early pronuclear transfer’, involves transplanting the nuclear DNA from a fertilised egg into a donated egg, which contains healthy mitochondria, on the day of fertilisation.
The study involving over 500 eggs from 64 donor women, indicates that the new procedure does not adversely affect human development and will greatly reduce the level of faulty mitochondria in the embryo. Their results suggest that the technique will lead to normal pregnancies while also reducing the risk of babies having mitochondrial disease.
The results of this study will be considered by the Human Fertilisation and Embryology Authority (HFEA) Expert Scientific Panel, which will ultimately decide whether to issue the first licence to a clinic.
A licensed clinic would allow couples affected by mitochondrial disease to have the choice of whether to use pronuclear transfer to try to have healthy children. Having overcome significant technical and biological challenges, we are optimistic that the technique we have developed will offer affected women the possibility of reducing the risk of transmitting mitochondrial DNA disease to their children, said Mary Herbert, professor at Newcastle University.
Extensive studies conducted in collaboration with researchers from University of Oxford and the Francis Crick Institute indicated that embryos created using the new technique are indistinguishable from those created by conventional IVF.
Analysis of thousands of genes in single cells detected no difference between the two types of embryos. There was also no increase in chromosomal abnormalities, which can cause miscarriage and birth defects. The findings provide reassurance that the new procedure does not have a harmful effect on early embryonic development.
They also indicate that the new technique will result in a minimal amount (less than 2 per cent) carryover of disease-causing mitochondrial DNA to the embryos. The importance of keeping carryover to a minimum is highlighted by studies on embryonic stem cell lines. We have found no evidence the technique is unsafe.
Embryos created by this technique have all the characteristics to lead to a pregnancy, said Doug Turnbull, Director of the Centre for Mitochondrial Research.
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