Mutations in CACNA2D1 plus KDM6B -- Gabapentin and Calcium Folinate? Perhaps PQQ? Perhaps BHB?

 

A little research can sometimes be eye opening

I was recently sent genetic results from several parents and surprisingly some have multiple potentially highly causal genes. Some are mutations that are extremely rare and one was unique.

Today I am looking at one case with two genes highlighted in whole exome sequencing (WES), one is a calcium ion channel and the other is a gene extremely close to the one causing Kabuki syndrome.  Interestingly, two possible interventions did very quickly appear.

The report states:

UNCLEAR RESULT

Variants of uncertain significance (VUS) identified

Based on current evidence, the clinical relevance of the detected variants remains unclear.

Kabuki syndrome is caused by mutations in KMT2D or KDM6A.

KDM6A and today’s gene KDM6B both target trimethylation on lysine 27 of histone H3 (H3K27me3), a mark associated with gene silencing. By removing this mark, they activate gene expression. So, mutations in either gene will cause a cascade of effects on numerous other genes.

The old post below suggested the use of HDAC inhibitors to correct the mis expressed genes. In particular, BHB from the ketogenic diet was discussed.

Notably, histone deacetylase inhibition rescued structural and functional brain deficits in a mouse model of Kabuki syndrome.

 

Ketones and Autism Part 5 - BHB, Histone Acetylation Modification, BDNF Expression, PKA, PKB/Akt, Microglial Ramification, Depression and Kabuki Syndrome

           

The calcium channel involved today is not one we have previously looked at, but it is the target of the very well-known drug Gabapentin. This drug is used to treat epilepsy and neuropathic pain. The child does have abnormal EEG and seizures, plus autism, ADHD and absent speech.

Mutations of the KDM6B causing autism were first described only in 2019. In 2022 mutations in this gene were found in several patients with cerebral folate deficiency (CFD), one of the authors is our old friend Dr Ramaekers.

We know a lot about CFD, thanks to our reader Roger, Dr Frye, Dr Ramaekers, and now Agnieszka and Stephen. Over in the US one of the founders of an autism organisation told me her son was diagnosed in adulthood with CFD, when he finally had a spinal tap.

Interestingly, Agnieszka has pointed out a novel way to potentially increase folate in the brain using an OTC supplement called PQQ.

 

Protective effects of pyrroloquinoline quinone in brain folate deficiency

Results

Folate deficiency resulted in increased expression of inflammatory and oxidative stress markers in vitro and in vivo, with increased cellular ROS levels observed in mixed glial cells as well as a reduction of mitochondrial DNA (mtDNA) content observed in FD mixed glial cells. PQQ treatment was able to reverse these changes, while increasing RFC expression through activation of the PGC-1α/NRF-1 signaling pathway.

Conclusion

These results demonstrate the effects of brain folate deficiency, which may contribute to the neurological deficits commonly seen in disorders of CFD. PQQ may represent a novel treatment strategy for disorders associated with CFD, as it can increase folate uptake, while in parallel reversing many abnormalities that arise with brain folate deficiency.

 

PQQ is a relatively common OTC supplement that looks helpful in older people and those with mitochondrial dysfunctions (most older people, plus many with autism).  It can also improve sleep.  The common 20mg dose seems to be based on what was used in a clinical trial in Japanese adults. Japanese drugs are dosed to reflect the size of Japanese people. American women on average weigh 40% more than Japanese women.

PQQ is present in mother’s milk, so it is not some scary artificial compound.

CFD looks like another nexus point where may different genetic variants produce a downstream meeting point.  This means numerous different underlying autisms will share a common beneficial therapy. It will not be a cure, but it should improve the outcome.

The only way to access I/V calcium folinate looks to be via confirmation of very low levels in spinal fluid, so a spinal tap would be necessary.  This is not easy, as Agnieszka has found out.  For some people oral calcium folinate is not sufficiently potent to reverse CFD.

KDM6B

Mutations of the KDM6B gene causing autism were first described only in 2019. In 2022 mutations in this gene were found in several patients with cerebral folate deficiency (CFD).

 

Genetic variants in the KDM6B gene are associated with neurodevelopmental delays and dysmorphic features

Lysine-specific demethylase 6B KDM6B demethylates trimethylated lysine-27 on histone H3. The methylation and demethylation of histone proteins affects gene expression during development. Pathogenic alterations in histone lysine methylation and demethylation genes have been associated with multiple neurodevelopmental disorders. We have identified a number of de novo alterations in the KDM6B gene via whole exome sequencing (WES) in a cohort of 12 unrelated patients with developmental delay, intellectual disability, dysmorphic facial features, and other clinical findings. Our findings will allow for further investigation in to the role of the KDM6B gene in human neurodevelopmental disorders.

 

Layman’s guide to the KDM6B gene

https://www.simonssearchlight.org/research/what-we-study/kdm6b/

 

12% of people with CFD studied in the paper below had mutations in KDM6B. So clearly all people with a mutation in this gene should be tested for CFD vis a spinal tap.

 

KDM6B Variants May Contribute to the Pathophysiology of Human Cerebral Folate Deficiency

Cerebral folate deficiency syndrome (CFD) was defined as any neurological condition that was associated with low concentrations of 5-methyltetrahydrofolate in the cerebrospinal fluid. Previous clinical studies have suggested that mutations in the folate receptor alpha FOLR1 gene contribute to CFD. In this study, we identified six genetic variants in histone lysine demethylase 6B (KDM6B) in 48 CFD cases. We demonstrated that these KDM6B variants decreased FOLR1 protein expression by manipulating epigenetic markers regulating chromatin organization and gene expression. In addition, FOLR1 autoantibodies were identified in CFD patients’ serum. To the best of our knowledge, this is the first study to report that KDM6B may be a novel CFD candidate gene in humans.

The way to confirm CFD, with certainty, is via a spinal tap.  This can then open the door to intravenous therapy with calcium folinate.

There is a blood test which then would lead to oral calcium folinate therapy.  This is now very common in children with autism in the US. It improves speech.

www.fratnow.com

The problem is that some people need the more potent intravenous therapy and without a spinal tap there is not enough proof to get the therapy.

 

CACNA2D1

The CACNA2D1 gene encodes voltage-dependent calcium channel subunit alpha-2/delta-1. 

Different types of mutation will have different effects and varying degrees of severity.

Some mutations in this gene are associated with a condition called “Developmental and Epileptic Encephalopathy 110”.

Developmental and epileptic encephalopathy-110 (DEE110) is an autosomal recessive disorder characterized by profound global developmental delay and hypotonia apparent in infancy followed by onset of seizures in the first months or years of life. Affected individuals achieve almost no developmental milestones and show impaired intellectual development, poor or absent speech, inability to walk or grasp objects, peripheral spasticity, and poor eye contact. Brain imaging shows hypoplastic corpus callosum and cortical atrophy.

CACNA2D1 is also a novel Brugada Syndrome susceptibility gene.

Brugada syndrome may be a major cause of sudden cardiac death in men under 40. People with Brugada syndrome on average die between the ages of 26 to 56 years, with an average age of 40 years. If treated appropriately, patients can have a normal lifespan.

A pediatric cardiologist should be consulted.

Fortunately the Alpha-2/delta proteins are believed to be the molecular target of the gabapentinoids gabapentin and pregabalin, which are used to treat epilepsy and neuropathic pain.

This means that an obvious path to investigate is whether the drug gabapentin has a positive effect. Mutations could produce either gain of function of loss of function.

Gabapentin binds to a the α2δ subunit. This binding does not directly block or open the channel, but it influences its overall activity.

The exact mechanism of action is still not fully understood, but it is believed that gabapentin:

·       Reduces the release of certain neurotransmitters involved in pain signaling, such as glutamate and substance P.

·       Alters the trafficking and function of the calcium channels themselves.

·       Therefore, gabapentin's action is more complex than simply "blocking" or "opening" channels. 

Gabapentin is not guaranteed to help in this case, but certainly might do.

Conclusion

The take home is really that if you invest thousands of dollars/euros/pounds in genetic testing, it is well worth your time spending some time on the internet looking up any flagged genes.

People expect too much from the geneticist writing the report.

Double check these things yourself.  Take your findings to an open-minded neurologist, who reads the research literature.

Be aware that the same mutation can be present in one or even both parents, with no noticeable negative effect, but be disease causing in their child. Genetics is often about the probability of something happening, rather the certainty. 

Look at partially-effective or sometimes-effective interventions in the research. For example, one reader is looking at mutations in NF1 plus a gene affecting epigenetics. He might want to try Lovastatin.  NF1 causes an increase in RAS, which is a pro-growth signal, this leads to RASopathies which can cause intellectual disability (ID). Lovastatin reduces RAS and it was trialled to reduce ID in NF1 - the results were mixed. It probably matters at what age you start trying to reduce RAS.

Takeaways from Thinking Autism 2023

I did present at the Thinking Autism 2023 conference in London recently.  I was last there in 2019 and there were many familiar faces.

Emotions were very much on show - joy, desperation, bewilderment, hope, fear, frustration and more.

The United Kingdom is amongst the worst countries in the world if you want to treat autism.  Even the idea of treating autism can get you into trouble. For severe autism it is much better to say treating ID (intellectual disability) – what sane person could object to that?

My takeaways are very specific to me, but here they are anyway.

 

So many doctors!

This year I was approached by many doctors who have children with ASD.  Among them were GPs, pediatricians, a neurologist, and a psychiatrist.

When you understand the basis of autism it is not surprising that so many doctors have kids with autism, particularly doctors married to a doctor.

 

Fertility treatment increasing the risk of autism

I did mention in my book the link between difficulty conceiving and having children with autism. Mothers who have had miscarriages are at risk of having a child with autism and children produced via IVF therapy have an elevated chance of autism.

One of the speakers at the conference, who uses diet as a therapy, told us that 30-40% of her patients where conceived by IVF therapy.  Wow – I thought. They are mainly children with milder autism, only 10% of her patients have severe autism.

 

From struggling to get on IVIG to how to come off it

Many parents struggle to get onto IVIG therapy for their child.  It is very expensive and, being an intravenous therapy, it is not so easy to administer to a child with severe autism.

Having finally got on IVIG therapy and responded well to it, how do ever wean the child off it, without losing all those gains?

This was a side issue arising from the conference and is an issue to some other readers of this blog.

What is very interesting is the potential to give IVIG therapy just once to very young children who developed normally but then suffer a regression into “autism.”  It seems to work for some. You might get it in Russia, but don’t bother asking in the UK.

 

My son is 14, I have tried everything else now I am ready for pills

Some people do respond well enough to dietary modification and OTC supplements, but more severe autism likely needs pharmaceuticals. For one mother at the conference she had come to this conclusion.  It is never too late to start to treat severe autism. Good luck to her!

 

Never give up

Never give up was the last point on my talk.

One mother at the conference was a very good example. She had finally had her twins examined at the UK’s top children’s hospital, Great Ormond Street Hospital (GOSH).  They have had MRIs, lumbar punctures to get spinal fluid samples and they have had genetic testing.  That is a triumph in the UK health system.

As she told us, she had to play the cancer card. She told her doctors “why do you go to such great lengths to save my life from cancer and yet do nothing for my twin boys with severe autism?”

Now one has a diagnosis of cerebral folate deficiency and one has a mutation is DISC1, a schizophrenia gene already covered, with therapy ideas, in my blog.  High dopamine in spinal fluid was only to be expected - it is a feature of schizophrenia. Light is at the end of the tunnel.  This mother was also very helpful to other mothers present.

 

School reporting on parent treating autism

I was disappointed to hear that a school had reported one mother for treating her child’s autism.

 

Ketones really do benefit some!

I did write a lot about the multiple possible benefits of ketones/BHB in autism.

The week before the conference one mother wrote to tell me that both she and her child with autism respond well to HVMN Ketone-IQ.

I knew our doctor reader Agnieska was a big fan of the BHB ester product Ketoforce, which seems to have disappeared during Covid.

At the conference a Spanish psychiatrist was listing the therapies in my blog that have helped his son and they included NAC, Bumetanide and BHB.

There are several new ketone products based on diol ketone esters, like HVMN Ketone-IQ.

Our reader Daniel mentioned very recently that he is using a product called DeltaG, a proprietary blend of diol ketone esters. HVMN Ketone-IQ is a pure diol ketone ester, while DeltaG is a proprietary blend of diol ketone esters.

The active ingredient in Ketone-IQ is R-1,3 Butanediol, also referred to as R-1,3-Butylene glycol, which maintains FDA GRAS status as a flavor molecule.

 

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=173.220

 

1,3-Butylene glycol (1,3-butanediol) may be safely used in food in accordance with the following prescribed conditions:

(a) The substance meets the following specifications:

(1) 1,3-Butylene glycol content: Not less than 99 percent.

(2) Specific gravity at 20/20 deg.C: 1.004 to 1.006.

(3) Distillation range: 200deg.-215 deg.C.

(b) It is used in the minimum amount required to perform its intended effect.

(c) It is used as a solvent for natural and synthetic flavoring substances except where standards of identity issued under section 401 of the act preclude such use.

 

This raw ingredient is very cheap.

Once it is packaged up as a supplement, it becomes very expensive.

As Agnieszka mentioned on the conference sidelines, you do have to look at the ingredients. In HVMN Ketone-IQ there is potassium benzoate as the preservative.  Potassium benzoate is a DAO inhibitor. DAO, or diamine oxidase, is an enzyme that breaks down histamine, a compound that can cause a variety of symptoms in histamine-sensitive people, such as headache, flushing, hives, and diarrhea.

 

“If my son can take the bus aged 20, I’d be happy”

One doctor mother showed me a video of her untreated young son with severe autism.  I told her how I have treated my son since 2012 and what the result has been. He passed his high school exams (GCSEs) in maths, science, geography, and English.  Now he has learnt how to travel independently from home by bus.  Time for those pills.

High dose Betaine/TMG, Low Dose Ponstan, Galavit, Humira, HMB (β-hydroxy-β-methylbutyrate) and Cetirizine for Palilalia/Scripting

 

Our reader in Canada, AJ, did highlight a case series from Norway that showed that high dose Betaine/TMG was effective in improving functioning in people with autism due to creatine transporter deficiency.  The use of Betaine/TMG was really just stumbled upon and the authors considered what the beneficial possible mode of action could be. 

Betaine (TMG) and Gene Therapy as potential alternatives to Bumetanide Treatment in Autism? 

The effect was only present at high dose (7-10 g a day) not the much lower dose used by some DAN/MAPS doctors, who do prescribe TMG and the closely related DMG.

The paper suggested that one possible effect might have been lowering chloride levels within neurons.  This is also the effect of Bumetanide.

AJ suggested that Betaine/TMG might be an alternative to Bumetanide and one that does not need a prescription.

Our reader Nancy reported a benefit in her adult son.

The question is not whether or not high dose TMG is a useful therapy, we already know that it is, in some cases. The question is whether it is a bumetanide alternative.

My conclusion is that high dose TMG does not seem to be a bumetanide alternative.  If it was an effective alternative then I would be suggesting everyone using bumetanide should go and buy some.

I did try TMG for s couple of weeks and did not see any additional effect over the continued therapy of 2mg of bumetanide.  In our case there is a benefit from additional bumetanide/Azosemide. If TMG shared the same mode of action as Bumetanide then 7g TMG + 2mg Bumetanide should show some improvement over 2mg Bumetanide.  It did not.

There is a long list of other modes of action to explain why Nancy’s son and the two Norwegians improved.

 

Low dose Ponstan for sound sensitivity

Low dose Ponstan (Mefenamic Acid) was proposed as a treatment for sound sensitivity.  Within Europe it seems that Greece is the place to buy Ponstan; it is sold OTC and cheap.  One pack (15 x 500mg) costs less than 2 USD/EUR.

In some people the effect of 250mg lasts all day, while for others it lasts for a few hours.

Ponstan is also widely used as a syrup to reduce fever in young children (antipyretic).

In the US the common brand name is Ponstel, but the price is dramatically higher.

Galavit + Cromolyn Sodium

The combination of the common mast cell stabilizer Cromolyn Sodium, used by many readers, with a Russian drug called Galavit is used by at least two readers. Dragos recently told us that the combination has put an end to his adult son’s aggressive behaviors.

Galavit has multiple anti-inflammatory modes of action.  It is not a mast cell stabilizer like Cromolyn Sodium.

Galavit is not expensive, but may hard to get hold of.

It does look like there is an overlap between responders to Verapamil and responders to Galavit.  So, if you respond well to Verapamil but get one of the rare side effects, like Maja’s daughter, it might be worth investigating further. 

Humira 

Humira is a TNF alpha inhibitor normally used to treat auto-immune conditions like rheumatoid arthritis, Cohn's disease, ulcerative colitis, psoriasis and juvenile arthritis.

I was recently contacted by an Aspie lady with auto-immune conditions, who found Humira not only controlled those conditions but moderated her autism symptoms, notably sound sensitivity.  One injection produced a benefit that lasted 7 weeks.

Kanner’s subject #1 went on to develop juvenile arthritis and this made his autism much worse.  There was no Humira back in his day, but his arthritis did respond to treatment.

Apparently, many children with autism and GI problems are taking Humira. 

IVIG seems to be the “go-to” therapy for immunomodulation in autism.  It is now quite commonly used in the US, but much less so elsewhere due to the cost.

I wonder if Humira might be an alternative for some?

 

HMB (β-hydroxy-β-methylbutyrate)

Our reader Natasa did mention the sports supplement HMB to me.

It has many interesting modes of action and it is a precursor to the ketone BHB, which has been covered in great depth in this blog.

Ketone Therapy in Autism (Summary of Parts 1-6)

In Europe ketone supplements like BHB fell foul of the rules on supplements and have been banned. In the US they are widely sold.

If you want to try BHB, by cannot buy it in Europe, you might want to look into HMB (β-hydroxy-β-methylbutyrate).

 

Cetirizine for Palilalia/Scripting 

I am a big fan of the OTC antihistamine Cetirizine/Zyrtec and I was interested to read the recent comment below about its effect on one 12-year-old boy.

“I realize this is 5 years old, but as a result of this blog, I tested cetirizine on my 12 yo yesterday. He has a nonstop palilalia (obsessive speaking that is nonsense or only makes sense to him). It's his "chief feature" and inhibits social development. For 4 glorious hours, it went away. Today, I gave him 5 mg of Zyrtec again. Yet again, the palilalia went away, AND he had strong focus on school (he has serious attention issues).”

 

Many people’s autism gets worse when auto-immune conditions flare up.  In some cases, the auto-immune condition is very mild, but the consequences are not.  For one person the result is aggressive behavior, while in another it is talking nonsense.

The Ketone D-BHB as a Medical Food for Heart, Kidney and Brain Disease (Alzheimer’s, some Autism …)

 Nestle’s research centre in Lausanne, Switzerland

I did write extensively about the potential to treat some autism using the ketone BHB (beta hydroxybutyrate). This can be achieved either by following a strict ketogenic diet or just by eating medical foods that contain/produce BHB.

Some readers are now big consumers of BHB supplements and anyone taking BHB should be interested in today’s paper, that I assume was paid for by Nestlé.

Nestlé make everything from baby milk formula to George Clooney’s Nespresso.  You may not be aware that they also have a business selling medical food; they have been looking at ketones to treat Alzheimer’s for some time.  This is quite similar to Mars developing Cocoa flavanols to improve heart and brain health.

Most ketone supplements are sold to help you lose weight or boost athletic performance.  The military also uses ketones in survival rations. 

We saw that you can increase the level of ketones in your body by supplementing: -

·        MCT oil (medium chain triglyceride oil, which usually contains about 60% caprylic C8 acid and 40% capric C10 acid).  This is a product already sold by Nestlé

·        Neat caprylic acid, C8

·        BHB salts (potassium, sodium, calcium etc)

·        BHB esters (also called ketone esters KE)

These products range from expensive to very expensive.

People requiring ketones as an alternative fuel to glucose, like those with Alzheimer’s need quite large amounts of the supplements.  In Alzheimer’s a glucose transporter at the blood brain barrier is restricting the flow of glucose in blood and so the brain is starved of “fuel”.  Mitochondria in the brain can be powered by both ketones and glucose, so if not enough glucose cannot get through, you have the option to increase the amount of ketones.

Babies fed with mother’s milk are on a high ketone diet.  You can safely combine both glucose and ketones as a fuel for your body.

The news from today’s paper has already been translated to a usable therapy. 

Metabolism of Exogenous D-Beta-Hydroxybutyrate, an Energy Substrate Avidly Consumed by the Heart and Kidney

There is growing interest in the metabolism of ketones owing to their reported benefits in neurological and more recently in cardiovascular and renal diseases. As an alternative to a very high fat ketogenic diet, ketones precursors for oral intake are being developed to achieve ketosis without the need for dietary carbohydrate restriction. Here we report that an oral D-beta-hydroxybutyrate (D-BHB) supplement is rapidly absorbed and metabolized in humans and increases blood ketones to millimolar levels. At the same dose, D-BHB is significantly more ketogenic and provides fewer calories than a racemic mixture of BHB or medium chain triglyceride. In a whole body ketone positron emission tomography pilot study, we observed that after D-BHB consumption, the ketone tracer ¹¹C-acetoacetate is rapidly metabolized, mostly by the heart and the kidneys. Beyond brain energy rescue, this opens additional opportunities for therapeutic exploration of D-BHB supplements as a “super fuel” in cardiac and chronic kidney diseases.

One of the main benefits of ketones is their ability to act as an alternative energy source to glucose or fatty acids for production of ATP by mitochondria. Caloric restriction and intermittent fasting also produce transient mild-moderate ketosis (6, 7).

While a high dose of MCT can provide a moderate increase in blood ketones (+0.5–1.0 mM), gastrointestinal intolerance and high caloric load limit their use. Second, ketone esters (KE) made of a BHB ester linked to butanediol provide one molecule of D-BHB after digestion, with the butanediol being further metabolized by the liver to D-BHB (9). KE increase blood ketones above 1 mM but are also limited at high dose by their gastric tolerability and severe bitterness (10).

Third, perhaps the most physiologic way to raise blood ketones is via the oral intake of D-BHB itself. Exogenous D-BHB is directly absorbed into the circulation, with some of it being converted to AcAc by the liver, and both ketones being distributed throughout the body. Until recently, only racemic mixtures of dextro (D) and levo (L) BHB (D+L-BHB) were available and oral human studies with them have been reported (9, 11–14). As L-BHB is not metabolized significantly into energy intermediates and is slowly excreted in the urine (9, 15), D+L-BHB would be anticipated to be less ketogenic than pure D-BHB. 

Levo, Dextro and Racemic

When certain chemicals are manufactured, they usually contain an equal mixture of the left-handed and right-handed version, this is called a racemic mixture. These versions are called enantiomers.

One enantiomer is an optical stereoisomer of another enantiomer. The two molecules are mirror images of each other, which are not superimposable - much like your left and right hand.

In the case of the chemical BHB, only the right-handed version has an effect on your body.  If you take the salt potassium BHB, half of the product has no effect other than raise your level of potassium.

Zyrtec is an antihistamine made of Cetirizine, but it is a racemic mixture.  If you want pure L-Cetirizine, you would buy Xyzal not Zyrtec.

Arbaclofen/ R-baclofen is the right-handed version of baclofen

Rezular/R-verapamil is the right-handed version of verapamil.

Back to the study:

The study compared three therapies: -

D-BHB

14.1 g of pure salts of the D enantiomer of D-BHB were used. The D-BHB supplement tested was formulated as a mixture of three salts: sodium D-beta-hydroxybutyrate, magnesium (D-beta-hydroxybutyrate and calcium (D-beta-hydroxybutyrate). Each oral serving provided 12 g D-beta-hydroxybutyric acid, 0.78 g sodium, 0.42 g magnesium, and 0.88 g calcium, citrus flavouring and sweetener (Stevia), dissolved in 150 mL of drinking water.

D+L-BHB

14.5 g of an equimolar mixture of commercial D and L beta-hydroxybutyrate salt was used (KetoCaNa, KetoSports, USA). Each serving provided a mixture of 12 g D+L-Beta-hydroxybutyric acid, 1.3 g sodium, 1.2 g calcium, orange flavoring and stevia, dissolved in 150 mL of drinking water.

MCT oil

Fifteen grams of medium chain triglyceride (MCT) (60% caprylic C8 acid and 40% capric C10 acid) emulsified in 70 mL of a 5% aqueous milk protein solution.

This chart shows the concentration of ketones in your blood plasma after taking either of the three therapies.

This chart shows the concentration of just the ketone D-BHB in your blood plasma after taking either of the three therapies.

 This chart shows the concentration of the ketone ACAc in your blood plasma after taking either of the three therapies.

  

This chart shows where the ketones are going; the chart shows the distribution of the ketone “tracer” acetoacetate (AcAc) by organ after D-BHB oral intake.  The effect is greatest on the heart and kidney, but some does reach the brain.

From the dynamic brain scan, CMR_AcAc and K_AcAc could be determined for all main regions of the brain and compared to baseline values previously determined in healthy young adults. Overall and compared to baseline, each region demonstrated an increase in CMR_AcAc and K_AcAc of ~4.7 and 2.3-fold, respectively, about 1 h after taking D-BHB. This indicated that AcAc is effectively taken by the brain and by other organs particularly the heart and the kidney.

Ketone production from an exogenous dietary source has been traditionally achieved by MCT. This requires a bolus intake to saturate the liver with MCFA, producing excess acetyl-CoA which is then transformed to AcAc and BHB, which are released into systemic circulation. The C_max achieved with MCT is usually between 300 and 600 μM, with higher values being difficult to reach due to GI side effects and liver saturation. Here we show that D-BHB, a natural and biologically active ketone isomer, raises blood ketone C_max above 1 mM without noticeable side effects. In comparison, an equivalent dose of D+L-BHB or MCT only achieved half this ketone level, with similar T_max at 1 h. Thus, compared to D+L-BHB, D-BHB significantly reduces the salt intake needed to achieve the same plasma ketone response.

Results from a previous study (9) comparing KE to D+L-BHB showed that at the same dose of D-BHB equivalent, the increase blood ketone iAUC had the same magnitude, suggesting that exogenous D-BHB and KE produce similar ketosis.

Note that KE means Ketone Ester and the study (9) is this one: -

On the Metabolism of Exogenous Ketones in Humans

Ketone esters are available, but horribly expensive and taste really bad.

Conclusion

In previous posts the numerous possible beneficial modes of action of BHB were outlined. The summary post is here: -

Ketone Therapy in Autism (Summary of Parts 1-6)

In practise some people with autism seem to benefit a lot, some moderately and some not at all.

Monty, aged 16 with ASD, fits in the “moderately benefits” category.  The combination of about 20ml of caprylic acid (C8) plus a scoop of Potassium BHB powder does produce more speech.

It is not a cheap or very convenient therapy, compared the others I use.

I would agree with Nestlé that the limiting factor with BHB salts is the “salt”.  As they comment in their paper 

“compared to D+L-BHB, D-BHB significantly reduces the salt intake needed to achieve the same plasma ketone response”

Giving someone with heart disease "sodium anything" is not a good idea. A potassium salt would be safer, but even then, your heart is the limiting factor on potassium use.  Calcium salts are unwise in people with autism, because it appears to be able to upset calcium ion signalling, which would also be a potential risk in heart disease.

As I mentioned to one parent who is a big time user of BHB salts, if you switch to D-BHB you can either produce twice the ketones of regular potassium BHB, with the existing potassium load, or reduce your dosage by half and keep the same effect and save some money.

I think potassium D-BHB is good choice.  If you are taking bumetanide you may no longer need a potassium supplement (K-BHB becomes your potassium supplement).

I think people with autism and genuine mitochondrial disease are highly likely to benefit from D-BHB.  These are people who show symptoms in their entire body, i.e. lack of exercise endurance. For these people, eating (or producing via diet) large amounts of ketones will increase the production of ATP in their brains and so improve cognitive function.  D-BHB undergoes a different process to glucose, as it “converted” to ATP by the process called OXPHOS
(Oxidative phosphorylation). Some people with autism lack the enzyme complexes needed to complete OXPHOS, these people who should try D-BHB.

BHB has other beneficial effects, some relating to inflammation that seem to explain its benefit in other types of autism.  The effects were investigated here.

In the brains of people with Alzheimer’s there is decreased expression of glucose transporter 1 (GLUT 1) at the blood brain barrier. This starves the brain of glucose, which is fuel for the brain. D-BHB is an alternative fuel for mitochondria that is not dependent on GLUT 1.  People with early onset Alzheimer's would seem the best ones for this therapy, that would include many people with Down Syndrome.