They are cruel diseases that kill 150 children in Britain every year, three times the number who die in car accidents.
However, despite decades of painstaking research backed by millions of pounds, there is still no cure for mitochondrial diseases.
It means that children diagnosed will likely see their condition progress for months or years before their body finally shuts down, often due to respiratory failure.
Indi Gregory’s harrowing battle with the disease has shed new light on the barely understood umbrella syndrome, an umbrella term for genetic disorders caused by mutations in mitochondria, described as the powerhouse of cells.
Eight-month-old Indi, who was at the center of a legal dispute over her treatment, died in the early hours of this morning after her breathing tube was removed.
Baby Indi Gregory, who was at the center of a legal dispute over her treatment, died after her breathing tube was removed.
Indi photographed at her baptism, alongside her parents Claire Staniforth and Dean Gregory.
Judges ruled that she should be taken off life support after doctors successfully argued that Indi was dying and that her treatment was causing her pain and would not save her life.
But last week, Italy’s Prime Minister Giorgia Meloni sensationally intervened and made her an Italian citizen in a last-minute legal bid to get her treated in a Rome hospital.
She never made it there and was moved from Queen’s Medical Center in Nottingham (QMC) to a hospice where she died in the early hours of today in her mother’s arms.
Approximately one in 4,300 babies is born with mitochondrial diseases each year.
Sufferers have mutations in their mitochondria (the cell batteries that give them energy for all bodily functions, from thinking to moving), meaning they do not provide enough energy for the cells to function properly.
Without energy, cells cannot function and begin to die.
The disease occurs due to a genetic defect in mitochondrial DNA (a small ring-shaped structure crucial for energy production) or nuclear DNA (the twisted ladder-shaped structure that is responsible for determining our characteristics).
Although incurable, not all children die in childhood.
Some patients manage to reach adulthood and live a fairly normal life.
It can also be difficult to diagnose as its symptoms overlap with those of other conditions.
However, doctors may suspect it when symptoms overlap.
A variety of tests are usually needed, including blood, cerebrospinal fluid, and MRIs. Genetic testing can also detect the condition, but is only available on the NHS if the patient is referred by the doctor.
Currently, medications can only slow the progression of mitochondrial disease and relieve symptoms.
However, a new wave of experimental drugs is being developed that researchers hope will prevent or reverse some symptoms of the disease.
Professor Sian Harding, an expert in cardiac pharmacology at Imperial College London, who has researched mitochondrial disease, told MailOnline: ‘Mitochondrial mutation diseases are particularly devastating, because mitochondria supply energy to every part of the body.
‘The special biology of mitochondrial DNA makes it even more difficult to treat than mutations in the core (nuclear) DNA.
‘The best current hope for couples in which the mother carries a mitochondrial mutation to have children free of the disease is egg donation to provide healthy mitochondria.
‘This is authorized and under investigation in the UK.
“Sadly, even that won’t offer a cure for children like Indi, who already suffer from this disease.”
A drug called EPI-743, also known as vincerinone, is expected to be able to treat some forms of mitochondrial disorders.
The tablet, manufactured by US-based Edison Pharmaceuticals, triggers the release of energy held by faulty mitochondria.
However, EPI-743, which is currently being tested, does not cure the underlying genetic defect behind the disease.
Early trials, involving terminally ill children in Europe and the United States, found that many showed improvement in their symptoms.
Other possible therapies include elamipretide, manufactured by the US pharmaceutical company Stealth Biotherapeutics, and omaveloxone, manufactured by Reata Pharmaceuticals in the United States.
Baby Indi Gregory with her mother Claire Staniford. The baby died after she was taken off life support.
Eight-month-old Indi (pictured with her father Dean), who suffered from an incurable genetic mitochondrial disease, had been in several High Court and Court of Appeal cases.
Elamipretide has been shown to help maintain mitochondrial function, while omaveloxone increases the efficiency of energy production in mitochondria, according to early studies.
Trials suggest that glutathione, manufactured by US-based Raptor Pharmaceuticals, could offer another treatment option by protecting against mitochondrial damage.
Meanwhile, studies in mice suggest that gene therapy could target and eliminate the DNA in the mitochondria that causes this devastating condition.
In Indi’s case, it is unclear what care she would have received in Italy for her mitochondrial disease.
The Bambino Gesu children’s hospital in Rome had offered to give him treatment that would help him breathe. “opening a valve by implanting a stent,” his father told Italian media last week.
«Then we can focus on his mitochondrial disease. We know that Indi is a fighter, she wants to live and does not deserve to die,’ he added.
Her family had already tried to persuade judges at the High Court and Court of Appeal in London and judges at the European Court of Human Rights in Strasbourg, France, to keep her on life support machines.
However, High Court judge Mr Justice Peel ruled that limiting treatment would be lawful and in Indi’s best interests.
Baby Indi Gregory, who was at the center of a legal dispute over her treatment, died after her breathing tube was removed.
The baby was transferred to a hospice on Saturday and died in the early hours of this morning.
Upon learning that doctors planned to take Indi off life support, Italian Prime Minister Meloni granted her citizenship last Monday and offered her care in Rome.
Doctors at QMC said Indi, who was born on February 24, was suffering from significant pain and distress and there was no point in further treatment.
On Saturday she was transferred to a hospice.
Her father Dean said: ‘Indi’s life ended at 1.45am My wife Claire and I are angry, heartbroken and ashamed.
‘Not only did the NHS and the courts take away the opportunity to live a longer life, they also took away Indi the dignity of dying in the family home where she belonged.
‘They managed to take away Indi’s body and dignity, but they will never be able to take away her soul.
‘They tried to get rid of Indi without anyone knowing, but we made sure she was remembered forever. He knew she was special from the day she was born. Claire held her until her last breath.
As news of Indi’s death spread, Meloni tweeted: “We did everything we could, everything we could. Unfortunately it wasn’t enough. Have a safe journey, little Indi.
Italian Deputy Prime Minister Matteo Salvini said this morning: “Little Indi Gregory is no longer with us, it is news we never wanted to read.” The Italian government took advantage of it and offered to treat it in our country, unfortunately without success. A moving prayer for you and a sincere hug for his parents.
