Genetic testing results

Click on the picture above to read about the upcoming event in London. There are familiar faces appearing, like Agnieszka, Dr Boles and indeed me.

 

I am quite often sent genetic testing results. There are many types of tests ranging from inexpensive tests looking at SNPs to the expensive WES or WGS tests.

SNP = Snip = Single Nucleotide Polymorphism = a tiny genetic spelling mistake

WES = Whole Exome Sequencing

WGS = Whole Genome Sequencing

There is a small industry based around selling expensive supplements for SNPs.

We all carry thousands of SNPs and I think these tests may often raise issues that are not causal.  The results from WGS or WES can be much more insightful.  A good example being in the comment recently posted on this blog.

 

I've been following your blog for many years, it's a real blessing and the perfect place to come and read for us, parents of ASD kids. My boy, 9, has non-regressive autism, is largely non verbal (one word sentence) and has pronounced OCD symptoms (similar to excoriating disorder, but aimed at the environment), hyperactivity and severe gut problems, recurrent vomitting, gastroparesis, etc. The only thing that visibly stopped the hyperactivity and inappropriate laughing and helped him sit for longer periods of time and read his books or watch whole movies was 0.5/kg mg Naltrexone daily, as advised by this paper https://pubmed.ncbi.nlm.nih.gov/16735648/. Lower doses saw the OCD creep back. As for his WGS test results, I've found relevant the fact that he has four pathogenic mutations in the EIF4EBP1, also a de novo mutation in the PIK3R1 gene and multiple other mutations in the STAT3, HTR3a, MAPT and also HLA-DRB1, HLA-DQA1, HLA-A, HLA-B, HLA-C, NRG1, NRG2, SCN4a, CACNA1S genes, amongst many others. We recently tried a course of Azythromycin for immuno-modulation, which saw his OCD reduced further, also his academic interest and focus increased visibly. He responds very well to Ibuprofen, AlkaSeltzer gold, Propranolol, Sytrinol and Cromolyn, but a quite long trial of Bumetanide two years ago did nothing for him. After all trials of various protocols and individual drugs, his gut is still bad, very often food seems to have major difficulty to pass though his digestive tract, no matter how finely tuned his diet is or how many prokinetics he takes. Given your extensive knowledge, I've always wondered what your take on the underlying problem/genetic pathway might be in his case (microglial activation, MTOR activation, perhaps?) and what drugs/cocktail of drugs might work best for his specific genetics and symptoms. He is a smart boy, has self-taught reading, loves music and masters his iPAD like a pro and, unlike what we know about autism, loves being around people. I cannot give up on him. We live in the UK, not the best place to even talk about treatments for autism. Please, if it's not too much to ask, tell me what other medications you thing it might boost his cognition further and help him start talking and develop more skills. Sorry for the long post. And thank you for any advice and ideas you might have to offer.

 

It would be useful to know which of the above mutations are present in at least one of the parents.  There so many possibly causal mutations here; I expect some are actually not relevant. In other words, it is not as scary at it may appear to be.

I do like to start with the easy part, which will be the ion channels.  Dysfunctions in ion channels (channelopathies) are often treatable with existing drugs and there is a great deal of information on each one.

 

CACNA1S

This gene encodes the calcium channel Cav1.1.

This is known as an L type calcium channel, the other ones being Cav1.2 and Cav1,3 and Cav1.4.

These ion channels are extremely important to how your brain works.  Because they also play a role in how your heart works, numerous drugs have been developed, some are more specific to one type of channel (Amlodipine for Cav1.3, Verapamil for Cav1.2).

The individual channels interact with other sub-types, so a mutation in one sub-type can affect other subtypes.

Very interesting in this case are the GI problems. There were efforts made a few years ago to develop R-verapamil as a drug to treat IBS/IBD under the name of Rezular. Some readers of this blog have reported that the only thing that resolves their child’s GI problems is an L-type calcium channel blocker.

Note Memantine, which is an Alzheimer’s drug that was subject to a very large autism clinical trial in the US.  The trial was deemed a failure, but one reader told me that Memantine is the only drug she had found that solved her child’s GI problems.  Memantine has several different modes of action, and a little reported one is blocking L-type calcium channels.

 

https://www.mdpi.com/1648-9144/49/9/64

Conclusions. Our results suggest that the neuroprotective effect of memantine could arise not only through the inhibition of the NMDA receptor current but also through the suppression of the L-type Ca²⁺ current.   

 

You might expect/hope a geneticist would suggest treatment with a drug like Verapamil.

  

SCN4a

This gene encodes the sodium ion channel Nav1.4.

This is one of the genes associated with Hypokalemic Periodic Paralysis (HPP), that was covered extensively in this blog. Interestingly the above Cav1.1 is also associated with Hypokalemic Periodic Paralysis (HPP).

The other genetic cause of HPP is KCNJ2 (an inward-rectifier potassium channel Kir2.1).

The immediate recovery therapy is drinking a potassium supplement.

A common preventative measure is acetazolamide (Diamox). This drug has also been covered in previous posts. The proposed mechanism is that it “increases the flow of potassium” – not sure what that is supposed to mean.

Some common anti-epilepsy drugs block Nav1.4 (Lamotrigine, Phenytoin etc).

All of the above-mentioned drugs have been used in autism. In specific cases they have shown a benefit.

You could ask your doctor to cautiously try them one by one.

Interestingly, the drug that seems to help many with sound sensitivity is Ponstan.  This cheap drug that affects the flow of potassium ions was proposed by Knut Witkowski as a therapy for 2-3 year olds to prevent non-verbal severe autism. 

 

EIF4EBP1

Here you mention there are 4 pathogenic mutations.

This gene is a real mouthful, but regular reader might recall the odd looking eIF4E part appearing in some previous posts

“This gene encodes one member of a family of translation repressor proteins. The protein directly interacts with eukaryotic translation initiation factor 4E (eIF4E), which is a limiting component of the multi subunit complex that recruits 40S ribosomal subunits to the 5' end of mRNAs. Interaction of this protein with eIF4E inhibits complex assembly and represses translation. This protein is phosphorylated in response to various signals including UV irradiation and insulin signaling, resulting in its dissociation from eIF4E and activation of cap-dependent mRNA translation.”

eIF4E inhibitors for Autism – Why not Ribavirin?

 

As you can see in the above post there are numerous ways to block elF4E. It is possible that the 4 mutations in your gene EIF4EBP1 could have the reverse effect in which case you would want to activate elF4E, not block it.

On the list, in my post above, is quercetin which is OTC and simple to try.

 

PIK3R1

A mutation in this gene can alter the PI3K/AKT/mTOR signaling pathway.

If this gene is causing a problem you might see some facial features a triangular face, a prominent forehead, small chin with a dimple, a loss of fat under the skin, prominent ears, hearing loss and delayed speech.

A mutation in this gene can lead to SHORT syndrome, which hopefully your pediatrician will have heard of.

 https://rarediseases.info.nih.gov/diseases/7633/short-syndrome

 

STAT3

STAT3 plays a key role in the immune system and elsewhere.

You can either have too much or too little STAT3.

In lay terms the immune system might end up either over-activated (hence benefiting from Ibuprofen and Cromolyn sodium) or under activated.

The immunomodulatory probiotics prescribed by gastroenterologists might be worth a try.

Lactobacillus rhamnosus GG

Lactobacillus plantarum 299v 

 

This might well reduce GI problems as well.

  

HTR3a 

This gene encodes subunit A of the type 3 serotonin receptor. It has lots of effects, but it may contribute to the vomiting.

It is associated with:

• Motion sickness
• Irritable bowel syndrome
• Social phobia
• Serotonin syndrome

For gastroparesis (impaired stomach's motility) the good drug seems to be Domperidone, which you should be able to get for free from your NHS doctor.

Another very popular therapy for gut dysbiosis of all kinds in some countries, but not the UK, is sodium butyrate. This has been mentioned in previous posts. It is an OTC supplement that will produce butyric acid in the gut and it helps restore a healthy mucosa. If you eat lots of fiber and have a healthy microbiome you would produce butyric acid naturally. The cheapest place in Europe to buy it is Poland, where they sell a product called Intesta Max (a weaker version is Intesta).  In the UK it is 3 times more expensive. Making friends with a Pole will save you money.

 

MAPT

The MAPT gene makes tau proteins.  There is a class of disease called tauopathy.

Tau Reduction Prevents Key Features of Autism in Mouse Models

 

Tau: A Novel Entry Point for mTOR-Based Treatments in Autism Spectrum Disorder?

 

As with the PIK3R1 mutation this will lead you to the idea of targeting mTOR signalling. You can inhibit this with Rapamycin, which has been used in autism.

 

Rapamycin/Sirolimus Improves the Behavior of an 8-Year-Old Boy With Nonsyndromic Autism Spectrum Disorder

 

One UK reader did get Everolimus prescribed on the NHS, but that was because the child was diagnosed with a genetic disorder called TSC. Several readers of this blog have tried Rapamycin as used in the Chinese case study.

If you do not have an over activated immune system, Rapamycin will cause the problem of an underactive immune system.

  

HLA-DRB1, HLA-DQA1, HLA-A, HLA-B, HLA-C,

 These genes all play a role in the immune system.

The human leukocyte antigen (HLA) system is a complex of genes in humans which encode cell-surface proteins responsible for regulation of the immune system.

The immune system uses the HLAs to differentiate self cells and non-self cells. Any cell displaying that person's HLA type belongs to that person and is therefore not an invader.

 

HLA Immune Function Genes in Autism

The human leukocyte antigen (HLA) genes on chromosome 6 are instrumental in many innate and adaptive immune responses. The HLA genes/haplotypes can also be involved in immune dysfunction and autoimmune diseases. It is now becoming apparent that many of the non-antigen-presenting HLA genes make significant contributions to autoimmune diseases. Interestingly, it has been reported that autism subjects often have associations with HLA genes/haplotypes, suggesting an underlying dysregulation of the immune system mediated by HLA genes. Genetic studies have only succeeded in identifying autism-causing genes in a small number of subjects suggesting that the genome has not been adequately interrogated. Close examination of the HLA region in autism has been relatively ignored, largely due to extraordinary genetic complexity. It is our proposition that genetic polymorphisms in the HLA region, especially in the non-antigen-presenting regions, may be important in the etiology of autism in certain subjects.

One specific HLA gene has been studied in autism.

 Inheritance of HLA-Cw7 Associated With Autism Spectrum Disorder (ASD)

Autism spectrum disorder (ASD) is a behaviorally defined disorder that is now thought to affect approximately 1 in 69 children in the United States. In most cases, the etiology is unknown, but several studies point to the interaction of genetic predisposition with environmental factors. The immune system is thought to have a causative role in ASD, and specific studies have implicated T lymphocytes, monocytes, natural killer (NK) cells, and certain cytokines. The human leukocyte antigen (HLA) system is involved in the underlying process for shaping an individual’s immune system, and specific HLA alleles are associated with specific diseases as risk factors. In this study, we determine whether a specific HLA allele was associated with ASD in a large cohort of patients with ASD. Identifying such an association could help in the identification of immune system components which may have a causative role in specific cohorts of patients with ASD who share similar specific clinical features. Specimens from 143 patients with ASD were analyzed with respect to race and ethnicity. Overall, HLA-Cw7 was present in a much greater frequency than expected in individuals with ASD as compared to the general population. Further, the cohort of patients who express HLA-Cw7 shares specific immune system/inflammatory clinical features including being more likely to have allergies, food intolerances, and chronic sinusitis as compared to those with ASD who did not express HLA-Cw7. HLA-Cw7 has a role in stimulating NK cells. Thus, this finding may indicate that chronic over-activation of NK cells may have a role in the manifestation of ASD in a cohort of patients with increased immune system/inflammatory features.

 

The therapeutic implication would be to look at immunomodulatory therapy.

At the simple level you have NSAIDs like Ibuprofen, but then you have the more potent drugs used to treat psoriasis, arthritis, IBD etc.

If you saw Dr Arthur Krigsman, the autism gastroenterologist, I guess he would prescribe Humira.  This is an injection you take every few weeks.  That very well might help your son in many ways. He does also come to Europe for consultations. You would need a colonoscopy.

Some British parents take their autistic kids with GI problems to Italy for treatment. You could ask the Thinking Autism charity who they go to see. One of these doctors presented at their conference in London in 2019.  He used some of Krigsman’s slides in his presentation.

 

NRG1, NRG2

Neuregulin 1 and 2 are implicated in brain disorders. NRG1 is well known as a schizophrenia gene, but it has been shown to be miss-expressed in autism as well.

NRG2 also plays a role in many neurological conditions.  

Neuregulins in Neurodegenerative Diseases 

The downstream effect of NRG1 is on epidermal growth factor (EGF). There are expensive cancer drugs like Lapatinib that are inhibitors of EGFR. 

As I have written in my blog, disturbed growth factors is a recurring feature of autism. This is why son many autism genes are also cancer genes. Don’t worry, this does not mean everyone with autism is going to get cancer.

 

Conclusion

Try and find a doctor who is interested to treat your son.

I think you will make great strides by treating the GI problems that you see every day.

I did meet an UK autism mother at that conference in London in 2019 who was told by her doctor that her son’s GI problems would not be treated in the UK and she should look abroad. She went to Italy and solved his problems.  It sounds so bizarre, I would not have believed it to be possible, had I not been talking directly to the mother.  I did talk to the Italian gastroenterologist at that same event.  Contact Thinking Autism and ask who was the Italian who presented in 2019.

Diamox & Bumetanide, Ion Channels Nav1.4 and Cav1.1, HypoPP, Autism and Seizures

So you’re going to spend some time at high altitude, climbing mountains or trekking, don’t forgetto pack your Diamox before you leave home, it can save your life.  She is right.

Today’s post links together subjects that have been covered previously.

It does suggest that there are multiple therapies that may be effective in the large sub-group of autism that is characterized by the neurotransmitter GABA being excitatory (E) rather than inhibitory (I).  The science was covered in the earlier very complicated post:-

GABA A Receptors in Autism – How and Why to Modulate Them

The growing list of potential therapies is:-

·        Bumetanide (awaiting funding for Stage 3 clinical trials in humans)

·        Micro-dose Clonazepam (trials in mouse models of autism)

·        Diamox (off-label use in autism)

·        Potassium Bromide  - to be covered in a later post (in use for 150 years)

Not surprisingly, all of these drugs also have an effect on certain types of seizure.

The optimal therapy in people with this E/I imbalance will likely be a combination of some of the above.

Periodic paralysis

Periodic paralysis (Hypokalemic periodic paralysis or HypoPP) is a rare condition that causes temporary paralysis that can be reversed by taking potassium.  A similar condition is hypokalemic sensory overload, when someone becomes overwhelmed by lights or sounds, but after taking potassium all goes back to normal. Autistic sensory overload, experienced by most people with autism, can also be reduced by potassium.

Though rare, we know that HypoPP is caused by dysfunction in the ion channels Na_v1.4 and/or Ca_v1.1.

For decades one of the treatments for HypoPP has been a diuretic called Diamox/Acetazolamide.

Other treatments include raising potassium levels using supplements or potassium sparing diuretics.

Bumetanide is a diuretic, but rather than raising potassium levels, it does the opposite.  So I always thought it was odd that bumetanide would have a positive effect on HypoPP.  But the research showed a benefit.

Autism and Channelopathies

We know that autism and epilepsy are associated with various ion channel and transporter dysfunctions (channelopathies).  In a recent post I was talking about Cav1.1 to Cav1.4.

Today we are talking about Cav1.1 and Nav1.4.

We know that Nav1.1 is associated with epilepsy and some autism (Dravet syndrome).

Nav1.4 is expressed at high levels in adult skeletal muscle, at low levels in neonatal skeletal muscle, and not at all in brain

Nav1.1 expression increases during the third postnatal week and peaks at the end of the first postnatal month, after which levels decrease by about 50% in the adult.

We saw with calcium channels that a dysfunction in one of Cav1.1 to Cav1.4 can cause a dysfunction in another dysfunction in another one of Cav1.1 to Cav1.4.

We also so that in autism the change in expression of NKCC1 and KCC2 as the brain matures failed to occur and so in effect they remain immature and therefore malfunction.

So it is plausible that sodium channels may also malfunction in a similar way. 

  

Acetazolamide efficacy in hypokalemic periodic paralysis and the predictive role of genotype

Hypokalemic periodic paralysis (hypoPP) is an autosomal dominant neuromuscular disorder characterized by episodes of flaccid skeletal muscle paralysis accompanied by reduced serum potassium levels. It is caused by mutations in one of two sarcolemmal ion channel genes, CACNA1S and SCN4A1-3 that lead to dysfunction of the dihydropyridine receptor or the alpha sub-unit of the skeletal muscle voltage gated sodium channel Nav1.4. Seventy to eighty percent of cases are caused by mutations of CACNA1S and ten percent by mutations of SCN4A4. 

There are no consensus guidelines for the treatment of hypoPP. Current pharmacological agents commonly used include potassium supplements, potassium sparing diuretics and carbonic anhydrase inhibitors (acetazolamide and dichlorphenamide). Dichlorphenamide is the only therapy for hypoPP to have undergone a randomized double blind placebo controlled cross over trial. This trial showed a significant efficacy of dichlorphenamide in reducing attack frequency but the inclusion criteria were based on clinical diagnosis of hypoPP and not genetic confirmation.

  

Ca_v1.1

Ca_v1.1 also known as the calcium channel, voltage-dependent, L type, alpha 1S subunit, (CACNA1S), is a protein which in humans is encoded by the CACNA1S gene

Na_v1.4

Sodium channel protein type 4 subunit alpha is a protein that in humans is encoded by the SCN4A gene.

The Na_v1.4 voltage-gated sodium channel is encoded by the SCN4A gene. Mutations in the gene are associated with hypokalemic periodic paralysis, hyperkalemic periodic paralysis, paramyotonia congenita, and potassium-aggravated myotonia.

Ranolazine

Ranolazine is an antianginal and anti-ischemic drug that is used in patients with chronic angina. Ranzoline blocks Na+ currents of Nav1.4. Both muscle and neuronal Na+ channels are as sensitive to ranolazine block as their cardiac counterparts. At its therapeutic plasma concentrations, ranolazine interacts predominantly with the open but not resting or inactivated Na+ channels. Ranolazine block of open Na+ channels is via the conserved local anesthetic receptor albeit with a relatively slow on-rate.

Muscle channelopathies:does the predicted channel gating pore offer new treatment insights for hypokalaemic periodic paralysis?

Beneficial effects of bumetanide in a CaV1.1-R528H mouse model of hypokalaemic periodic paralysis

Transient attacks of weakness in hypokalaemic periodic paralysis are caused by reduced fibre excitability from paradoxical depolarization of the resting potential in low potassium. Mutations of calcium channel and sodium channel genes have been identified as the underlying molecular defects that cause instability of the resting potential. Despite these scientific advances, therapeutic options remain limited. In a mouse model of hypokalaemic periodic paralysis from a sodium channel mutation (NaV1.4-R669H), we recently showed that inhibition of chloride influx with bumetanide reduced the susceptibility to attacks of weakness, in vitro. The R528H mutation in the calcium channel gene (CACNA1S encoding CaV1.1) is the most common cause of hypokalaemic periodic paralysis. We developed a CaV1.1-R528H knock-in mouse model of hypokalaemic periodic paralysis and show herein that bumetanide protects against both muscle weakness from low K⁺ challenge in vitro and loss of muscle excitability in vivo from a glucose plus insulin infusion. This work demonstrates the critical role of the chloride gradient in modulating the susceptibility to ictal weakness and establishes bumetanide as a potential therapy for hypokalaemic periodic paralysis arising from either NaV1.4 or CaV1.1 mutations.

Mode of action

The research does state that nobody knows why Diamox is effective in many cases of hypoPP.

My reading of the research has already taken me in a different direction.  While researching the GABA_A receptor that is dysfunctional in some autism, it occurred to me that in addition to targeting the NKCC1 receptor with bumetanide, another way of lowering chloride levels within the cells might well exist.

I suggested in an earlier post that Diamox could be used to target the AE3 exchanger.

What Diamox (acetazolamide) does is lower the pH of the blood in the following way.

Acetazolamide is a carbonic anhydrase inhibitor, hence causing the accumulation of carbonic acid Carbonic anhydrase is an enzyme found in red blood cells that catalyses the following reaction:

hence lowering blood pH, by means of the following reaction that carbonic acid undergoes

In doing so there will be an effect on both AE3 and NDAE, below.  This will change the intracellular concentration of Cl-, and hence give a similar result to bumetanide.

This would also explain the phenomenon cited below that pH affects the excitability of the brain.

Over excitability of the brain is the cause of some of the effects seen as autism and clearly Over excitability of the brain will be the cause of some people’s seizures/epilepsy.

Not surprisingly, then one of the uses of Diamox is to avoid seizures.

Acetazolamide in the treatment of seizures.

  

Anion exchanger 3 (AE3) in autism

Anion exchange protein 3 is a membrane transport protein that in humans is encoded by the SLC4A3 gene. It exchanges chloride for bicarbonate ions.  It increases chloride concentration within the cell.  AE3 is an anion exchanger that is primarily expressed in the brain and heart

Its activity is sensitive to pH. AE3 mutations have been linked to seizures

Characterization of an Epilepsy-associated variant of the AE3 Cl-/HCO3-exchanger

Bicarbonate (HCO₃^-) transport mechanisms are the principal regulators of pH in animal cells. Such transport also plays a vital role in acid-base movements in the stomach, pancreas, intestine, kidney, reproductive organs and the central nervous system.

Two types of chloride transporters are required for GABA_A receptor-mediated inhibition in C. elegans

Abstract

Chloride influx through GABA-gated Cl⁻ channels, the principal mechanism for inhibiting neural activity in the brain, requires a Cl⁻ gradient established in part by K⁺–Cl⁻ cotransporters (KCCs). We screened for Caenorhabditis elegans mutants defective for inhibitory neurotransmission and identified mutations in ABTS-1, a Na⁺-driven Cl⁻–HCO₃⁻ exchanger that extrudes chloride from cells, like KCC-2, but also alkalinizes them. While animals lacking ABTS-1 or the K⁺–Cl⁻ cotransporter KCC-2 display only mild behavioural defects, animals lacking both Cl⁻ extruders are paralyzed. This is apparently due to severe disruption of the cellular Cl⁻ gradient such that Cl⁻ flow through GABA-gated channels is reversed and excites rather than inhibits cells. Neuronal expression of both transporters is upregulated during synapse development, and ABTS-1 expression further increases in KCC-2 mutants, suggesting regulation of these transporters is coordinated to control the cellular Cl⁻ gradient. Our results show that Na⁺-driven Cl⁻–HCO₃⁻ exchangers function with KCCs in generating the cellular chloride gradient and suggest a mechanism for the close tie between pH and excitability in the brain.

NKCC1 and AE3 Appear to Accumulate Chloride in Embryonic Motoneurons

Abstract

During early development, γ-aminobutyric acid (GABA) depolarizes and excites neurons, contrary to its typical function in the mature nervous system. As a result, developing networks are hyperexcitable and experience a spontaneous network activity that is important for several aspects of development. GABA is depolarizing because chloride is accumulated beyond its passive distribution in these developing cells. Identifying all of the transporters that accumulate chloride in immature neurons has been elusive and it is unknown whether chloride levels are different at synaptic and extrasynaptic locations. We have therefore assessed intracellular chloride levels specifically at synaptic locations in embryonic motoneurons by measuring the GABAergic reversal potential (E_GABA) for GABA_A miniature postsynaptic currents. When whole cell patch solutions contained 17–52 mM chloride, we found that synaptic E_GABA was around −30 mV. Because of the low HCO₃⁻ permeability of the GABA_A receptor, this value of E_GABA corresponds to approximately 50 mM intracellular chloride. It is likely that synaptic chloride is maintained at levels higher than the patch solution by chloride accumulators. We show that the Na⁺-K⁺-2Cl⁻ cotransporter, NKCC1, is clearly involved in the accumulation of chloride in motoneurons because blocking this transporter hyperpolarized E_GABA and reduced nerve potentials evoked by local application of a GABA_A agonist. However, chloride accumulation following NKCC1 block was still clearly present. We find physiological evidence of chloride accumulation that is dependent on HCO₃⁻ and sensitive to an anion exchanger blocker. These results suggest that the anion exchanger, AE3, is also likely to contribute to chloride accumulation in embryonic motoneurons.

 

Conclusion

So the science does confirm that “chloride accumulation following NKCC1 block was still clearly present”.  This means that bumetanide is likely only a partial solution.

We also see that “anion exchanger, AE3, is also likely to contribute to chloride accumulation in embryonic motoneurons” and “that chloride accumulation that is dependent on HCO₃⁻”.

This is a subject of some research, but it is still early days.

Bicarbonate homeostasis in excitable tissues: role of AE3 Cl−/HCO3−exchanger and carbonic anhydrase XIV interaction

  

I suggest that Diamox, via its effect on HCO₃⁻, may affect anion exchanger AE3 and further reduce chloride accumulation within cells.  This may have a further cumulative effect on GABA.

As we saw earlier, bumetanide does indeed shift GABA from excitatory to inhibitory in people who neurons remain in an immature state (like those of a typical two week old baby).  To my surprise, the use of micro-dose Clonazepam, as proposed by Professor Catterall, but in addition to Bumetanide, has a further effect on GABA’s excitatory/inhibitory imbalance.

Taken together this would highlight the possible further benefit of Diamox.

Normal blood pH is tightly regulated between 7.35 and 7.45.  I do wonder if perhaps in some people with autism, the pH of their blood is slightly elevated (alkaline), this would contribute to excitability of the brain.

Since Diamox increases the oxygen carrying capacity of the blood, I further wonder if this additional oxygen may also be beneficial in some cases.  Since some people are adamant that hypobaric oxygen therapy has beneficial (although not sustained) effects in autism, surely a better treatment would be Diamox?

Since the body is controlled via so-called feedback loops, perhaps in a small subset of people with autism who respond to extra O₂, they actually have blood pH that is higher than 7.45.  In which case measuring blood pH would be a biomarker of who would respond to hypobaric oxygen therapy.  Not surprisingly then, trials of hypobaric oxygen therapy in autism fail, because most of the trial subjects do not have elevated blood pH.

  

So there are many reasons that Diamox should be trialed in autism.  I did find one (DAN) doctor currently using it, but they do not really explain why.

Biomedical Treatment of the Young Adult with ASD