According to several headlines the house of commons has
today voted to allow three
parents to collude in sharing their DNA to create an unnatural and
experimental GM baby. The embryos created under the new mitochondrial donation
law will indeed technically contain DNA of three parents, but the term is
unhelpful and misleading in the extreme.
"The biggest problem is that this has been described as
three-parent IVF. In fact it is 2.001-parent IVF,"
Dr Gillian Lockwood, reproductive ethicist
As anyone who did Biology at school knows, the mitochondria
are vital bits of cell equipment that use oxygen to generate chemical energy
from glucose. They are descendants of ancient bacteria-like cells that were
engulfed very early on in life’s evolution. They each retain a tiny genome
consisting of a handful of genes that are essential for the fundamental process
of respiration.
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Mitochondrial DNA
|
Nuclear DNA
|
|
Approx. 16,600 base pairs
Approx. 37 genes
All from Mother
Needed to produce energy for cells to function.
|
Approx. 3,300,000,000 base pairs
Approx. 25,000 genes
46 chromosomes – 23 each from Mother and Father.
Codes for all other processes.
Determines appearance and characteristics. |
Mitochondrial DNA mutates more quickly than nuclear DNA as
it isn't subject to the same proof-reading mechanisms. In common
with nuclear DNA, small changes in the sequence can cause dysfunction and
disease, such as Leigh’s disease. Babies born with Leigh’s (which causes
profound physiological disruption including diarrhoea, vomiting, developmental
delay, and failure of the muscles, eyes, heart and lungs) survive for only a
few years. A human egg cell contains about 10,000 mitochondria, of which any
number may be faulty any other children the mother of an affected baby has may
well suffer with the disease too. Replacing these faulty mitochondria with
working ones is a bit like replacing a faulty heart, or transfusing blood.
http://gentle-interventions.org/what_are_mitochondrial_diseases.htm
MPs have backed the mitochondrial donation regulations by
382 votes to 128 - a majority of 254.
If passed through the House of Lords, doctors will be able
to apply for a license from the human fertilisation and embryology authority
that allows them to implant a patient’s healthynuclear DNA
into a cell that contains healthy mitochondria, thereby eliminating
the transmission of disease caused by mitochondrial DNA errors, and preventing
its transmission to all subsequent generations too.
This law allows the UK to continue advancing medical science
and has the potential to reduce disease burden and improve the lives of many
people.
There is still quite a lot of opposition to this for some
reason. Some people, including the pro-life groups, believe that human life
begins at conception. A harder position to defend, or articulate, is that using
this technology to eliminate mitochondrial disease is “playing God” and that
this is a bad thing (and presumably using medical technology to fight cancer
and infections and organ failure isn’t playing God and is fine). Still others
(such as cartoon Tory Jacob Rees-Mogg) argue that we take a step onto a
slippery slope that ends in parents dictating more and more details about their
children until they are selecting them out of a catalogue. To be clear
mitochondrial DNA doesn’t code for any characteristic of a person, and in any
case the HFEA already have clear rules about only excluding embryos with clear
genetic disorders (over 250 on their
list) that would significantly adversely affect their lives.
As far as I can there is no significant difference in any of
these arguments from those that were used to oppose “test-tube” babies born
using IVF, where several embryos are created and healthy embryos are selected
to be implanted into the mother. There are legitimate concerns as to whether
IVF or mitochondrial donation is necessary when adoption and egg donation is
available, and it remains controversial whether this type of treatment should
be available on the NHS. However, IVF technology has been shown to be
very effective and quite acceptable to most people too. I see no reason why
mitochondrial donation is different.
