28. What are my reproductive choices?
This involves using the egg of a donor woman combined with sperm of the father.
This treatment is effective for both mitochondrial DNA defects (mutations) and for nuclear DNA defects and ensures the resulting child will be free from Mitochondrial Disease.
The child will be genetically related to the father but not the mother.
This involves using the sperm of a donor male combined with egg of the mother.
This treatment is only effective for nuclear DNA defects but ensures the resulting child will be free from Mitochondrial Disease.
The child will be genetically related to the mother but not the father.
IVF with Preimplantation Genetic Diagnosis (see Q27)
This technique involves IVF treatment using the mother's egg and the father's sperm and as such, the resulting child will be genetically related to both parents. The process involves creating a number of embryos through the normal IVF process and then screening the embryos using a process called Preimplantation Genetic Diagnosis (PGD). The aim is to identify embryos that look healthy and are either free from disease or carry low levels of mutation.
The screening process is very effective for nuclear DNA mutations as it can give a definite yes or no answer.
Results for mitochondrial DNA mutations however, may be less clear. Clinicians are able to test embryo's and advise families the % mutant loan (the % level of faulty mitochondria present). This % is then compared against theoretical 'disease thresholds'. Disease thresholds are the % of abnormal mitochondria, above which, they believe disease symptoms may appear. Clinical experience in the UK suggests that for PGD, a mutant load of 30% or less should result in asymptomatic or unaffected individuals although this may vary depending on the underlying genetic mutation.
Sometimes embryo mutant load %'s may be close to the threshold level, which means families are not be able to obtain the assurance they need, to be confident the child would be free from disease. Q29 gives more information on new developments which can help families in this situation.
For some women who carry only faulty mitochondrial DNA mutations (ie. 100% faulty mitochondrial DNA or 'homoplasmic' mutations), this technique will not be successful. For these families, and for families where PGD has been unsuccessful, there has recently been a medical breakthrough called Mitochondrial Donation.
This technique involves using the mother's egg, the father's sperm and the healthy mitochondria from a donor woman. The resulting child will be genetically related to both parents and will have a tiny 0.02% of mitochondrial DNA from the donor woman.
This treatment is only suitable for mothers that carry mitochondrial DNA defects but it can help some families when IVF with PGD cannot.
UK legislation was passed in Feb 2015 to allow this technique to be offered on a case by case basis to suitable affected families.