I’ve just spent a few minutes trying to work out how I’m going to crack the code on the punch key that keeps the childcare centre secure and then I’m inside thanks to a mum who enters the numbers for me. At the end of a long corridor I’m greeted by a beaming smile from a pretty, petite, brunette. Wilmarie Craig.
I’m here to talk to her about her daughter Angela. Two days a week when Angela is feeling well, she can be found here, at the daycare centre, where, like any of the other kids, she will be burning off joules in an endless burst of noisy activity.
Today Angela’s energy level is bright and unwavering but when she flags, which happens every two to three weeks,
“She’ll have a day where she gets up and she’ll fall over.
“She can’t see properly and she walks into walls.”
She is also unbalanced, so Wilmarie wonders about her hearing.
On these days Angela lies on the lounge and stays there.
“I call them her recharge days.”
Recharge is essential otherwise her body retaliates and she has absence seizures. She desaturates and while most parents just carry around some wipes, Wilmarie Craig has more unusual and cumbersome items, like an oxygen tank, and an oximeter.
In [gs March 2011] Angela suffered her first seizure and was flown up to Townsville hospital from Dysart. The doctors did an MRI and her brain appeared normal. Six months later she suffered a huge cluster that left her catatonic. After numerous tests, including a lumbar puncture, Angela had another MRI. It showed brain damage.
“It was what you’d expect from a newborn.”
“It was completely black rather than having grey areas and the black extended down through her brain stem as well.”
Angela was drooling excessively. At first Wilmarie didn’t think too much about it “…after all she was a toddler,” but it got worse and she couldn’t swallow properly. The doctors had no idea what was going on. An initial diagnosis was given of Panayiotopoulos syndrome
“Just unexplainable, benign childhood epilepsy that can go within a couple of years,” says Wilmarie
Eventually a diagnosis was made. Three weeks before Angela’s second birthday she was diagnosed with [gs Mitochondrial Disease],(mito disease) subgroup suspected [gs Leigh Syndrome] They were told, ‘Look you’re just going to have to take her home and enjoy her.’
“The way she was presenting they didn’t expect her to live very much longer,” says Wilmarie.
Wilmarie began an intense and continuing biology lesson discovering the role mitochondria play in human disease.
Mitochondria exist in most of our cells, especially within the high energy systems such as the heart, brain, nerves, muscles, bowels, eyes, ears and hormone producing glands.
They perform many functions necessary for cell metabolism, but the energy-producing pathway is the most important. This pathway, which breaks down carbohydrate, fat, protein, and oxygen to make the energy molecule, adenosine triphosphate (ATP) is called oxidative phosphorylation.
Over 70 different polypeptides or proteins, located on the inner mitochondrial membrane, make up the complex mitochondrial respiratory chain, also known as the “electron transport chain” (ETC) and allow OXPHOS to occur. This highly efficient manufacturing process, called aerobic metabolism, only happens in the mitochondria. It produces approximately 90% of the energy needed by the human body.
Mitochondria also play an intimate role in most of the cell’s major metabolic pathways that build, break down, or recycle molecular building blocks. Cells cannot make the RNA and DNA they need to grow and function without mitochondria.
Energy sources such as glucose are initially metabolized in the cytoplasm then imported via proteins at the beginning of the ETC. Other proteins continue the process of catabolism using metabolic pathways such as the Krebs cycle, fatty acid oxidation, and amino acid oxidation.
This produces energy-rich electron donors whose electrons are then passed through the ETC (a series of complex molecules I, II, III, and IV). Cytochrome oxidase or complex IV, passes the electrons to oxygen which is reduced to water.
ATP synthase or Complex V then uses the electrochemical proton gradient produced by the respiratory chain to make ATP. Although electron transport occurs with great efficiency, a small percentage of electrons are prematurely leaked to oxygen, resulting in the formation of the toxic free-radical superoxide.
These five ‘structures’ that make up OXPHOS are encoded by both nuclear DNA and mitochondrial DNA (mtDNA). Thirteen proteins coded by mtDNA are part of complexes I, III, IV and V.
Simply put, even at rest, humans need to constantly generate about 100 watts of energy, the same amount as a bright light globe. This allows our neurons to send messages, our heart to pump and our organs to perform. Each day we generate and consume about 65 kilograms of ATP.
The only saving grace for Wilmarie, if you can call it that, was that the following year Angela was also diagnosed with autism spectrum disorder (ASD) leaning towards the aspergers side and she got financial help from the government. There are no government financial resources available to mito sufferers.
Autism is a common symptom or presentation of mito and while it can have other reasons to occur, there is usually no cause. Karen Crawley a doctor who was ignorant of mito until her daughter started to have stroke like episodes says, mito is commonly unrecognised in these patients as they hide under their symptoms of idiopathic autism.
“Hence we get back to it’s favourite name….”the notorious masquerader”….it hides in other illnesses.
“So really any complicated ASD, complicated epilepsy, complicated diabetes, etc…….mito should be thought of.”
Wilmarie would like to get another MRI for Angela but the anaesthetic can accelerate the disease. The last MRI showed brain damage which they were told was irreversible.
She says Angela has regressed but now she’s progressed past the point where they understood she could expect to. Her language skill has improved. She doesn’t need a speech therapist anymore and she is socialising, “in incredible ways.”
“I want to see what’s happening.
“If all the old pathways that should have died have died what’s happened in her brain to make her capable of doing what she’s doing now?”
But as Crawley says mito is a cruel affliction and, “You are constantly second guessing the health of your child.” The sad reality for Angela and her family is that the disease is progressive and fatal.
It’s a week or so later, and after some confusion with time frames, I’m talking to Crawley on Skype. It’s late and she has the kids sorted. Then, suddenly, she’s distracted. “Sorry I just got a very long winded text from the help line. I didn’t know you could send texts that long.” She laughs.
Her daughter Kara was diagnosed with MELAS , a common subgroup of mito, at age 8 after she had a stroke like episode.
Karen relates the frustration, frustration that is echoed throughout the mito community, in trying to find out what was wrong with Kara.
The doctors and specialists were oblivious. Karen says Kara lost all her baby teeth by the age of seven. Her mouth was x-rayed and the specialist told Karen that he could see her adult teeth, so there was no need for further investigations.
Kara was extremely clumsy and uncoordinated but that was shrugged off too, along with her toe-walking, very tight calf muscles, excess body hair, halted growth and failed occupational therapy assessment.
She had droopy eyelids, [gs ptosis] but because she was reading and doing well at school, “Don’t worry.” “It can’t be too serious.” Karen says Kara did well at school, despite her physical problems, because she loves schoolwork
“She’s a determined sausage and that kept her up there,”
But she was slow and she looked like she was in a daydream all the time. So we took her to the psychologist and were told, she’s just lazy.
“So we got the ‘proverbial’ whip out, but that was her top gear.”
This was the pattern from age 3 to nearly 8 years of age. At 7, Kara started puberty.
So three weeks before her eighth birthday, Kara saw an endocrinologist. This was the first time that someone had suggested “something genetic” to help explain Kara’s “bad luck.”
A few tests were organised including a head and spinal MRI scan, blood tests, x-rays and an eye review. But everything was appearing unremarkable.
On Monday morning, a week after her last test and after a fun-packed weekend celebrating her birthday Kara was in bed extremely drowsy and vomiting. This progressed to seizures and unconsciousness a few hours later. A preliminary diagnosis of a viral encephalitis was made.
The next day, with seizures persisting and tests not showing any sign of organisms, just high lactate, the reportedly ‘normal’ MRI from a week earlier was reviewed. An old stroke and cerebellar atrophy were discovered. Karen believes because the MRI was organised by an endocrinologist the reporting specialist only focussed on the hormone producing parts of the brain.
“I think they got a bit of a rap over the knuckles for missing that”.
When this “old” stroke occurred is difficult to know says Karen, except that Kara had what appeared to look like severe gastroenteritis at age 3. Karen recalls she looked very similar with drowsiness and repeated vomiting, but no seizures. Blood tests in emergency appeared “off”, so she was kept for a few days to be re-hydrated. Otherwise, all of Kara’s other issues up to age 8 were quirky and simply ‘hard work’.
With this ‘normal’ MRI now reviewed, an urgent repeat MRI was performed which showed a new stroke developing in a different part of the brain. By the end of the second evening a clinical diagnosis of [gs MELAS] was given and confirmed two weeks later with a genetic test
Thinking back says Karen, “It all seemed pretty straight forward”.
“All of her symptoms are all classical mito signs, once you know what you’re looking for.”
It took Karen at least 6 months to get up enough courage to find out about Kara’s disease.
“….My mind wasn’t ready to deal with it until the following year .”
She searched the internet, bought a new medical textbook, hoping and expecting to see a more detailed explanation than the one sentence in her old book, but discovered only a few more words, but what she did discover broke her heart.
“You are essentially going to watch your partner, child or whoever turn into a vegetable.
Dying from mitochondrial disease can be like dying from several illnesses. It can confer the pain of bone cancer, the dementia of Alzheimers, the breathlessness of lung failure and the muscle weakness of motor neurone disease.
“I thought this couldn’t be this shitty.
“Of all the things and I never knew this nasty piece of work was out there.”
Kara’s disease was affecting her whole system. Her eyesight, her bowels, her hearing, her muscles, her nerves, her mind and understanding, her swallowing, her speech, and common to MELAS an over-expenditure of energy which can cause strokes.
After Kara’s diagnosis Karen met up with and joined a team of medicos, specialists and research scientists who were behind the Australian Mitochondrial Disease Foundation [gs AMDF]. As well as managing medical education for the public and medical practitioners, she helps raise funds, increases awareness, and she says, “Goes wherever else the journey takes her. She is also the author of a booklet entitled, ‘Mito Disease Depleting LIfe’s Energy’ a medical information booklet for general practitioners. (available at http://www.amdf.org.au)
In 2009 Karen started the [gs AMDF help line] providing advice and referral services for mito patients. I asked her how people find the help line. She tells me about a man in Sydney. He’s seen five neurologists “He has classic MELAS symptoms.” One of them [neurologist] raised his arms up and said I don’t know what you’ve got–some stroke like illness.
‘The guy toddles off in his wheelchair and ‘googles’, ‘stroke like illness’’.’ He finds four pages of information and the AMDF website. He questions why google can get it right but not the specialist.
As part of its crusade to raise awareness in 2010, the AMDF booked an information stand at the major general practitioner conference, GPCE, in Sydney. Karen was in charge of crash tackling passers by. Of the hundreds of doctors and other health professionals Karen spoke to she says, “Only about five or so knew what mitochondria were and what cells they were in.”
And Karen says a lot of them weren’t interested in finding out.
“We felt like used car salesman.
“Trying to sell them something they didn’t want.
“Because it’s coined rare they think they are never going to see it so they don’t have to bother learning about it.”
For serious illness the stats are 1 in 5,000, with 1 in 200 of the general population carrying mitochondrial disease causing genetic defects. That equates to about 100,000 Australians.
Those carrying a genetic defect, 1 in 25 will die from it at a young age or as a young adult. Then Crawley says, somewhere in between there is an unknown percentage of the population who present with a broad spectrum of mild forms of the illness, most likely never to be diagnosed.
I ask about the progression of the disease, Crawley says the general rule of thumb is the younger they are the nastier it is and the younger they die. The later you start, the slower the disease progresses. “If you present at say 40 to 50 you may not die until 70 but you will look like a very old person at a young age.”
To add to the complexity and because of [gs heteroplasmy] how sick you get depends on how many mitochondria are affected and how badly.
Some children may seem to have severe disease and live to 40 or 50, or even older. Whereas, some adults who may appear to have mild disease suddenly develop a severe complication like a cardiomyopathy with heart failure and die.
“If you think of it as a scale out of 10 [my daughter] Kara is 9 out of 10.
“She started at 3 but was diagnosed at age 8.”
These serious sufferers, the ones on a scale of 7, 8, 9 or 10, are slowly getting better diagnosed. However, the mild forms are rarely diagnosed.
“I’m a classic example.
“I’ve got the MELAS gene and suffer from a slow bowel and reflux, along with a few minor symptoms like some autonomic dysfunction, and now intermittent tinnitus”.
“Do you call that mito or do you call that bad luck or coincidence?” She says if she started to go deaf, or had a stroke or developed liver or kidney problems, then she could get a clinical diagnosis.
“We try not to over-diagnose mito, but wait until three or more definite systems are affected.”
Except some of the mito subgroups that affect one system such as [gs LHON] and PEO.
[gs Dr Doug Lingard]’s eldest son Alex died from an unexplained neurological illness in 1983 at the age of 7 and a half.
Then in 2007 his 20 year old daughter Rose developed convulsions. Doug went back to the research neurologist who had looked after Alex and was told that in hindsight he thought Alex had died of something called ‘mitochondrial disease’ – the first time Doug, a radiologist and nuclear physician, had heard of it. After countless seizures, two induced comas, months in hospital and many tests a diagnosis of POLG gene mito was diagnosed.
When Rose was diagnosed Lingard discovered there was very little information, no support network, and almost total lack of awareness amongst the medical profession. The RACGP ‘bible’ ‘Principles of General Practice’ contained no mention of mito.
So says Lingard many people, particularly those with milder disease, were undiagnosed or misdiagnosed, and unknowingly at risk of passing the disease on to their children. Many were labelled hypochondriacs and told their problems were psychosomatic, often for years.
He agrees yes its difficult to know how to classify and diagnose mito but it can be done. The diagnosis can be described in three ways, a clinical diagnosis, a biochemical diagnosis and a genetic diagnostic. The clinical diagnosis is based on presentation; eg Leigh syndrome, MELAS, CPEO, KSS, LHON plus many more including Huntington’s disease, some forms of muscular dystrophy and autism.
The biochemical diagnosis is based on mitochondrial respiratory chain energy generation (ATP production, oxygen consumption rate and other measurable indicators of mitochondrial function) and is usually obtained from a muscle biopsy. Examples include Complex I, II III, IV and V abnormality, or coenzyme Q10 (C0Q10) deficiency.
Finally, the genetic diagnosis is based on the presence of mtDNA or nuclear DNA (nDNA) mutations; eg [gs POLG]] gene mutations and at least 200 others.
The difficulty is there is so much overlap. A biochemical abnormality can produce several different clinical syndromes and result from several different gene mutations, and any one gene mutation may produce different respiratory chain (RC) complex abnormalities and different clinical syndromes.
Professor Carolyn Sue a mitochondrial disease specialist who operates a clinic in Sydney has offered a list of observational and [gs investigational tests] for the general practitioner (GP) or specialist to help assess and diagnose mito disease.
If you really want to know, after a clinical or biochemical diagnosis, the exact mutations you can have a mitoexome which will look for point mutations and deletions. This should take a few weeks and cost about $7,000.00, non- rebatable dollars.
Patients with mtDNA deletions have two types of DNA. They always have some normal/healthy/wild-type mtDNA, which is a circle of 16,569 base pairs (bp). The other form of mtDNA they have is a deleted molecule, which is basically missing a big chunk. The deleted species is smaller and could be half the size of normal, or 3/4, or some other fraction. mtDNA deletions knock out multiple genes so are grossly dysfunctional.
However, if you have enough healthy mtDNA, then a small amount of deleted mtDNA isn’t a problem. Once the amount of deleted mtDNA exceeds a threshold though it results in cellular dysfunction and disease. That threshold varies between tissues. mtDNA deletions are usually sporadic events i.e. there is usually no family history, at least for single deletions, where there are just the two types of mtDNA present (fullsize and deleted).
Some patients have multiple mtDNA deletions for example instead of fullsize and one size of deletion, they have a mix of deleted mtDNAs of different sizes. These are problems caused by nuclear genes and have different types of inheritance (autosomal dominant or autosomal recessive).
mtDNA depletion is where there is not enough mtDNA ie the problem is not a deletion or a change in the sequence of the mtDNA, but that the cells can’t make enough of it. So instead of having maybe 2000 copies of mtDNA per liver cell, there may only be 100 or 200, which is not enough for the cells to make enough mitochondrial proteins.
Be aware, as Lingard points out many nDNA abnormalities produce mtDNA abnormalities. Meaning you may have to do a whole genome investigation, which will take a lot longer and considerably more dollars.
[gs Dr David Thorburn] is one of the few handful of mitochondria research scientists in Australia and runs the main diagnostic lab for muscle biopsies from kids around Australia and New Zealand. He’s been studying mito for 20 odd years.
He and other research scientists are looking at the genes involved in mito diseases using new gene sequencing technologies.
Next generation sequencing [gs NGS] may be helpful in identifying genes causing mutations. Its also an infant technology and produces very complex data. Thorburn shares an analogy he once heard. The numbers of letters in our genetic code is three billion bases. Bases are equivalent to letters. That’s the number of letters in 1,000 copies of War and Peace. So if you were trying to work out a change in gene sequence it may be as difficult as finding the typo in one letter in one of the thousand volumes and it could be one letter in one word or it could be the deletion of a whole chapter. Plus the data needs to be compared next to a healthy genome.
Research by Thorburn and 16 others, with Sarah Calvo taking the lead. performed ‘mitoexome’ sequencing of over a thousand genes encoding all the known mitochondrial proteins on young children with mito.
They not only identified the known defects [in 24% of cases] but also discovered two new nuclear genes not previously linked to disease and since then he says, “..We have found 7 more.”
One of the new genes found by the research was named: C6orf125 which means its the 125th open reading frame or 125 predicted gene on chromosome 6 and Thorburn says at the time we didn’t know what the hell that one did.
So we found mutations in that gene and then we had to work out what the gene was doing. They collaborated with a group in the Netherlands who did some “funky bioinformatic analyses” and recognised that there was a relationship with that gene and one in yeast that was implicated in mito function.
When a new gene is found, there is no confirmation of whether that gene will be the cause of that patient’s symptoms or whether it will create the same symptoms in another patient.
“So if you’re looking at genes as a diagnostic classification it has its disadvantages.”
Sean Murray, CEO of AMDF, has several family members who are affected by mito. His maternal grandmother was deaf and she suffered what the family thought were strokes. She also had cognitive impairment and was incapacitated right up to her death at 68. His grandmother’s sister also shared the same symptoms.
In 1998 Sean returned from his honeymoon to the news that his older brother, Peter, who was 34 at the time was in hospital. They believed he had had a stroke. That was obviously extremely bizarre says Sean that a young man, who otherwise appeared to be relatively fit and healthy, was in hospital after a stroke. He was being medicated and was psychotic, supposedly in reaction to the medication.
When they started to look into the family history it was not long before a diagnosis of mito was given..
“That was the first we had heard of it.”
Soon after, his mum and all of his sisters, tested positive for mito. Sean and his three sisters were shown to carry the same genetic mutation that causes [gs MELAS].
Meanwhile Peter recovered from the stroke and while Sean and his sisters can’t remember whether Peter’s hearing loss happened prior to the stroke or after, it deteriorated fairly significantly over the following years. Then out of the blue, he got tonsil cancer. Sean recalls thinking how unlucky can this guy be. He had surgery and started a course of radiotherapy. After that Sean says Peter deteriorated rapidly. The radiation treatment affected his neck muscles and he found it hard to hold up his head. His ability to produce saliva was impaired, which made it harder for him to swallow, and it affected his voice box.
So six years after the initial stroke like episode Peter, who was in his early forties and who was, basically, “…a disabled man with a young family,” had another stroke like episode. Sean remembers he was grateful that at least the hospital were now aware of drug contraindications. Particularly to drugs that are used to treat epilepsy (seizures) like Sodium Valproate.
Sean says, “They were giving him some pretty serious drugs and again he become psychotic. He was given sedatives and comatised. He recovered; to a state of ill-health.
Then on the day Sean’s son was born his mother had her first stroke like episode. Since her early forties, her hearing had been getting worse, and her general health had been deteriorating. His mother had to have extensive rehabilitation.
In 2008 Sean’s brother then had another chronic episode. He was back in hospital. Around the same time Sean was contacted by Doug Lingard under the guise of AMDF and was asked to be their ‘website’ guy.
When the foundation was officially formed in February 2009 Sean was one of the founding directors with Doug Lingard and a number of other people from the scientific and medical community.
It was in June 2009 of that year that Sean’s brother went back into hospital. His doctors had noticed some signs that were a precursor to another stroke like episode. He deteriorated quickly and on the 13 June he passed away.
“It was a huge shock.”
“His health had been deteriorating for so long we expected it was coming but it was still shocking for us.”
After that Sean says he become even more committed to the AMDF. As the AMDF grew Sean was offered, and, accepted, an appointment as its CEO, but his celebrations were short lived as he was greeted with news that his mother had passed away. Sean says after Peter’s death, “I don’t know if my mum lost the will or what happened but she was chronically sick from that period on to a point where she was in a wheelchair.”
Sean recalls it being a very intense period.
“It was very in my face as to what the disease was doing and I really felt that it gave me some resolve and motivation to try and work in this area to make a difference.”
He considers his own mortality saying he’s 41.
“I’m not getting any younger.”
He suffers cramps in his calf muscles and in his feet and they’re getting worse. The cramping is a known symptom of mito resulting from lactic acidosis.
“It can’t beat me,” says Sean.
The complexity and relative infancy of mito disease means there are no real options for treatment.
An initial hypothesis and research led to the supplementation of CoQ10 or ubiquinone, meaning it is ubiquitous in all biological systems. It’s an essential part of the ETC and an antioxidant and Thorburn says maybe that’s the way its acting.
He says that initially researchers thought that [gs oxidative stress] within the cell could be a problem. If there’s a block in the ETC then it could be reducing the conversion of oxygen to water which leads to generation of [gs ROS]. This can damage proteins, lipids and DNA.
The way the field is evolving Thorburn says there is not a whole lot of evidence that oxidative damage itself is a problem but that the changes in the increased amount of ROS is causing a problem with signalling pathways in the cell. He says this could possibly be making cells behave badly or even die.
“If it [CoQ10] does work, and as a co-author of a Cochrane review of current mito treatments, he has doubts, “I suspect what it is doing is perhaps mopping up the free radicals, not so much preventing direct damage to the mitochondria but preventing changes in cell signalling that are leading to other problems”.
If you are diagnosed with mito the chances are you will end up ingesting a ‘Mito Cocktail’. A smorgasbord of vitamins, minerals and co-enzymes, including the abovementioned CoQ10. The term cocktail becomes apparent when you consider there may be up to 50 pills involved. These are mega dosages which really should be administered by a medical professional.
These various supplements are used because they are involved in the energy making process somehow. They can/may boost mitochondrial OXPHOS or related functions. CoQ10 is involved in electron transfer between complex I and complex III and also between complex II and complex III. It also acts as an anti-oxidant.
Vitamin B2– complex I, complex II. Vitamin B1– pyruvate dehydrogenase, which is an enzyme that links glycolysis (first stages of glucose oxidation occurrinjg in the cytosol) to mitochondrial oxidative metabolism. Pyruvate dehydrogenase deficiency causes similar symptoms to OXPHOS diseases eg Leigh syndrome, episodic ataxia, Magnesium orotate. Orotate may boost mitochondrial production of nucleotides needed for DNA & RNA synthesis. Magnesium is needed for any reactions involving ATP
Crawley says medicos prescribe them mainly so they can be seen as doing something that might help the patient.
While the Cochrane review authored by Thorburn and others questioned the efficacy of most of these supplements this was based more on the lack of the gold standard requirement for medical research and the need for further and better studies rather than a definitive statement of non-efficacy.
Crawley says many patients, anecdotally, find them effective. They commit to taking the cocktail for six weeks and if they find a benefit they continue, if not, they stop. After stopping they may then realise that they were in fact providing some benefits. The general starting point for a ‘cocktail’ is CoQ10, magnesium orotate, occasionally carnitine, and varying combinations of other vitamins.
Professor Carolyn Sue prescribes a basic formulae that, can change from patient to patient, it consists of Mg Orotate, Vitamin B1 and B2, Vitamin E, Vitamin C and CoQ10. Crawley says Idebenone can be substituted for CoQ10, a synthetic version, available over the internet, with claims that it’s 1000 times more potent.
Sue also prescribes the cocktail to other family members with the genes, in the hope it may stop them getting the illness. Overseas the long list of ingredients can be put together by a compounding pharmacist so that patients don’t have to take large numbers of pills every day, which Crawley says is an issue with mito patients who already have difficulty swallowing.
Cocktail ingredients are not available on the PBS (Pharmaceutical Benefits Scheme) and can cost up to $300 per month. Crawley says the cost for bulk compounding could bring the price down to about $130 per month, but would need a guaranteed patient list of at least 100 to turn stock over, since many of the supplements have a short shelf life. Occasionally, the childrens hospitals supply some of the supplements through their own pharmacy but the adults have to fend for themselves, says Crawley.
Crawley provides Kara with what she says is an abbreviated version of the mito cocktail. It consists of arginine, carnitine, and a multivitamin powder called Seravit.
Kara is also given vitamin D, potassium, phosphate and calcitriol. The supplements are not part of the mito cocktail but are given because of her osteopenia (weak/thinning bones) and ‘leaky’ kidneys.
She eats about 1-2 tablespoons of food per day on average. Karen says its hard to gauge as she won’t eat for weeks then she has a few very small bowls over a few days. She struggles to chew as she gets tired after the third or fourth mouthful, forgets to swallow, chokes and gags. The strokes have affected the muscles around and in her mouth. She finds it hard to do what we take for granted, the simple coordination of tossing the food around in her mouth and chewing. In the main Kara is fed with a type of baby formula via a gastrostomy tube.
In the field of pharmacology, what looks really promising says Thorburn is treatment with a drug called Rapamycin. In a study published in Science using a mouse model researchers discovered they were able to extend the lifespan of the mice from 50 to 150 days and improve motor performance.
But the researchers questioned the action of the drug. Its an immunosuppressor so its not suitable for chronic use. Thorburn says it could be reasonable and useful to trial it with kids that have lethal presentations It’s also useful “for proof of principle” paving a smooth way for research into related drugs, with the same benefits–minus the side effects.
Another area that has promise he says is ‘boosting’ the number of healthy mito or mitochondrial biogenesis using targeted drugs. The reasoning behind this is as Thorburn explains if you had a complete block in the mito generating energy pathway you would never be born. A complete block is not compatible with life. Every patient has some sort of residual capacity. Say for example you have a ten or 20 percent residual capacity, just enough to get you by, apart from when you’re exposed to nasty stressors, like viral illnesses, certain drugs, growth spurts and other hormonal changes, if we could double that number that would mean you had 20 or 40% mito capacity.
What about the likelihood of magnifying the bad mito? It appears drugs like bezafibrate and resveratrol, and there is some data to support this, will boost all mito numbers This area of research has some promising studies in mice that needs to be fine-tuned including the suitability for human trials. My ears prick up at the mention of the word resveratrol. Isn’t that the compound in wine? Yeah. But at the level of compound required, drinking that much wine is also not compatible with life, says Thorburn.
Lingard says it’s imperative to set up an Australian patient registry. Without a registry ‘homogenous study populations’ needed for gold standard trials will be like finding a needle in a haystack.
The first trials for a drug called EPI743 failed he says because they just didn’t have the participant numbers or the right phenotypes. Clinical trials have again been instigated for EPI743 efficacy.
Thorburn also says the problem with clinical trials is the variability in disease progression which questions whether the results are due to the miracle of the intervention or just chance because patients tend to have episodic deteriorations interspersed with periods of stability.
In any genetic disease a discussion of reproduction options is warranted. For some women with a known diagnosis of DNA and some women with mtDNA mito, especially the ones who carry a low mutant load, IVF techniques like preimplantation genetic diagnosis are useful. This involves growing an embryo to the eight cell stage and performing genetic tests to ascertain how many of the DNA or mtDNAs are healthy and how many are mutant. Based on the results a choice is then made about which embryo is implanted.
Then there is a pre-natal diagnosis where at say 11 weeks of pregnancy you take a sample of the chorionic villus, a precursor of the the yet undeveloped placenta, or take amniocytes obtained from the amniotic fluid by amniocentesis. The number of mtDNAs are viewed and again from a consideration of the number of healthy vs mutant cells a determination is made as to what the outcome will be for the child.
So far Thorburn and others have done about ten or so of the mtDNA prenatal diagnosis and in conjunction with Melborne IVF have done one preimplantation genetic diagnosis. As far as Thorburn knows all of thee children born from these procedures are healthy but he says that really neither is a good option because at this stage, for most mtDNAs, no-one knows what level of mutant/healthy mtDNAs causes disease.
Thorburn summarises two studies that have potential for minimising the risk of transferring mito disease to future generations. In 2009, a group from Oregon reported using a nuclear transfer method to show it was possible to transfer nuclear material between monkey eggs, without substantial transfer of mtDNA. They showed that the manipulated eggs could be fertilised and developed into embryos that became healthy baby monkeys.
This approach could potentially be used to prevent mitochondrial DNA disease in humans by allowing couples at risk of mitochondrial DNA disease to have children who carried the nuclear genes from the parents and mitochondrial genes from a healthy donor. This technique is called [gs maternal spindle transfer] (MST)
In another study researchers from the UK used a similar but slightly different approach to show that it was also possible to perform nuclear transfer successfully in fertilised human eggs. The scientists were able to take the nuclear genes from one embryo, leaving nearly all of the mother’s mitochondrial DNA behind, and transfer them to another embryo from which the nuclear genes had been removed. They showed that the resulting embryos could develop normally to the 100-cell stage. This technique is called [gs Pronuclear transfer] (PNT).
The major achievement of PNT is that it shows that nuclear transfer in human embryos can allow apparently normal embryonic development. The major technical difference from the monkey study was that the current study used pronuclear transfer between fertilised eggs rather than transfer of the chromosomal spindle complex between unfertilised monkey eggs.
Both approaches have advantages and disadvantages so it is not certain yet which method may be technically superior if used on humans in the future.
Apart from the technical success and great potential promise of these studies, it is likely to spark further debate about whether it is appropriate to perform these experiments on human embryos. The embryos for the studies were not generated for research but for IVF treatment for couples affected by infertility or at risk of a genetic disease. The scientists only used embryos that were unsuitable for IVF because they contained too few or too many copies of nuclear genes from one parent, namely 23 chromosomes or 69 chromosomes rather than 46 chromosomes.
In order for the experiments to proceed, Thorburn’s understanding is that they required an amendment of British legislation for this specific purpose, as it otherwise forbids manipulation of the human germ line as part of laws to prevent human reproductive cloning. The scientists received special approval to perform the experiments described and grow the embryos up to the 100-cell stage but no further. The justification was largely on the basis of potential harm versus potential benefit in using this technique to prevent serious genetic diseases.
In addition to the ethical issues, which require further community debate there are some practical issues that will delay the potential introduction of nuclear transfer to prevent mitochondrial DNA disease. This procedure would currently be illegal in virtually all countries so its introduction would require legislative change and approval of specific protocols.
Further information needs to be provided on potential safety issues related to the chemicals and proteins used in removing and transferring pronuclei and to the possibility of so called epigenetic changes that may arise from mixing together the nuclear genes from one embryo with the cytoplasm (cell body) of another.
As I’m writing this (March 2014) there is an application to the US Federal Drug Administrator (FDA) for the consideration of PNT in clinical trials. The Human Fertilisation and Embryology Authority (HFEA) in the UK is also undergoing public consultations to discuss both PNT AND MST with a view to develop regulations to allow further research and clinical trials.
Thorburn says another ethical issue that was discussed in relation to the monkey study, was whether the resulting children would have three genetic parents. Technically this is correct, as the donor egg containing mtDNA is likely to come from an unrelated woman. However, the mtDNA contains only a very small number of genes that are essential for converting food energy into chemical energy. They do not appear to play a role in behaviour, appearance or other characteristics.
I must say I have to wonder whether we (collectively) have had this argument before? Crawley says, “…what a load of gaff, has anyone considered how many DNA are passed from organ donors, but as a christian she is quick to point out she is loathe to consider the use of embryos as in the PNT technique.
Thorburn says it could be argued that the genetic influence of a third parent is greater in surrogate pregnancies, since the environment of the womb is now recognised to program the way various genes are expressed and to potentially affect health outcomes later in life.
The other issue that is raised by the working group for the Nuffield Council on Bioethics is the branding of the techniques as falling within the area of germline therapy. Who owns the child is another consideration and finally should we start breeding only boys?. The only definitive answer to some of these discussions was a unanimous yes to the procedures being viewed as ‘germline therapies’. The writer assumes this will provide ethical and legal boundaries in terms of future research. Whether that is good or bad, remains to be seen and is definitely not within the scope of this article.