Scientists have edged closer to a breakthrough with three-parent babies, a procedure which uses an IVF technique involving DNA from three people to create a baby.
This could be a reality by the end of next year following successful pre-clinical analysis. The process is considered to be controversial because it could lead to the child having the DNA of three parents – the extra one being from what is effectively a second mother.
Scientists at Newcastle University are trying to help women who are at risk of passing on serious genetic disorders to have a healthy child.
They have been experimenting with the process to see if replacing an egg’s disease-prone mitochondrial DNA with that of a healthy female donor could head off inherited conditions such as muscular dystrophy.
Mitochondrial replacement therapy replaces a small amount of a mother’s faulty DNA in her egg with healthy DNA from another woman.
More commonly known as three-parent babies, the experimental technique means that babies inherit genes from a father and two mothers. The technique will be used in normal pregnancies.
By removing the faulty DNA, scientists are able to reduce the chance of babies having mitochondrial diseases which are passed through the maternal line spreading from mother to child. They are rare but serious conditions which tend to emerge in childhood and can sometimes prove fatal before adulthood.
The illnesses, many of which affect the brain and muscles and worsen as children grow, are produced by genetic mutations in tiny structures called mitochondria that sit inside cells and provide them with energy. They are passed on exclusively from mother to child, but mothers can be carriers without having symptoms.
Using mitochondrial donation, doctors hope to block the transmission of faulty mitochondrial DNA by making IVF embryos that have the normal set of chromosomes from the parents, but healthy mitochondria from a donor.
Previous studies have shown the process is technically feasible in abnormally fertilized human eggs, yet they have had limited capacity for onward development.
A study involving more than 500 eggs from 64 donor women found that the new procedure did not adversely affect embryo development and significantly reduced the amount of faulty mitochondria being passed on.
Scientists have however acknowledged that despite some successes with the process, there was a risk of up to four percent of mutated, disease-causing DNA carrying over.
Last year the UK became the first country to approve laws to permit the procedure. Parliament has allowed the process to go ahead, but further tests have been called for by the Human Fertilisation and Embryology Authority (HFEA).
The HEFA will ascertain whether it may be granted a license, enabling the procedure to later become available to women as a treatment.
Critics argue the “three-parent babies”procedure unnecessarily medicalizes children’s lives and conception. However, proponents argue it provides invaluable help to families who carry severe hereditary conditions, saving them unnecessary suffering and distress.