Dr Sai, Chief Embryologist at Malpani Infertility Clinic explains the nitty gritty behind mitochondrial donation

1. TREATING MITOCHONDRIAL DNA DISEASES
Dr. Sai, Chief Embryologist, Malpani Infertility Clinic Pvt. Ltd.
What are Mitochondria?
• Mitochondria are small complex structures, which exist in every cell of the body, except
red blood cells.
• Mitochondria produces most of the energy we all need to live and grow.
• In other words Mitochondria are the powerhouses which convert the food we eat into
energy.
• There are from 1 to several hundred Mitochondria in each cell.
• Mitochondria performs many functions necessary for cell metabolism but the energy
producing pathways are most important
• These pathways allow us breakdown carbohydrate, fat etc. and turn into energy.
What are mitochondrial diseases?
• When mitochondrial DNA contains genetic defects, the mitochondria do not work
properly, so do not produce enough energy. This results in mitochondrial DNA disease.
• Mitochondrial DNA disease is a genetic disease.
• Most of the cell DNA is contained in the nucleus but a very small (>1%) is found in the
mitochondria.
• Alterations in mitochondrial DNA result in a number of relatively rare but very serious
diseases
• Healthy and diseases Mitochondria can exist in the same cell
• When the proportion of diseased mitochondria, compared to healthy mitochondria,
reaches a certain amount(>60%) that a disease may occur.
• Some patients will have predominately brain and nerve disease. Others will have
muscle, cardiac, endocrine, renal or bone marrow diseases.

2. • Symptoms vary depending on which organs are affected. They can include loss of
control over movement, muscle weakness and pain.
What are the symptoms of mitochondrial DNA disease?
• It can result in heart disease, disorders of the stomach and intestines and disorders of
the brain.
• The severity of mitochondrial DNA disease varies from mild to extremely debilitating,
and it can result in death in childhood.
• Mitochondrial DNA defects leading to mitochondrial DNA disease are often passed
down from mother to child.
How are Mitochondrial DNA diseases transmitted?
• Those who inherit faulty mitochondrial DNA can develop symptoms or be carriers of the
condition without experiencing symptoms, and in both cases they are able to pass the
defects on to their children
Mitochondrial DNA disease can be prevented using Mitochondrial Donation
What can be done to prevent it?
Faulty mitochondrial DNA from a mother’s egg can be replaced with healthy mitochondrial DNA
from a donor egg.
This prevents mitochondrial DNA defects from being inherited, so the child that develops from
the egg will not get mitochondrial DNA disease.
What techniques are used in mitochondrial donation?
1)
Two techniques can be used for mitochondrial donation:
This technique is very difficult and need expertise to perform it.
Maternal Spindle Transfer
We need Spindle View, an additional equipment to connected to our inverted microscope
in order to view a Spindle. We cannot see a spindle looking at the egg under a normal
microscope.
Maternal Spindle Transfer involves removing the nuclear DNA (which contains 99.9% of the
total cell DNA) from the donor egg, leaving the part of the cell containing the healthy
mitochondria. The nuclear DNA from the mother’s egg is then inserted into this cell. The

3. healthy egg is fertilised and is then implanted into the mother’s uterus in the same way IVF
is carried out already.
2)
This Technique is simpler as compared to Spindle Transfer.
Pronuclear transfer
Pronuclear Transfer is similar to Maternal Spindle Transfer but involves fertilising the
mother’s egg first and then transferring the nuclear DNA to the fertilised donor egg
containing healthy mitochondria, from which the original nuclear DNA has been removed.
The healthy fertilised egg is then implanted.