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Other therapeutic interventions include:
- ethosuximide and other anticonvulsant drugs
- GHB receptor antagonist NCS-382
- GABA receptor modulators
- uridine
- acamprosate
- dopaminergic agents
- dextromethorphan
- glutamine
- antioxidants
- Lamotrigine
The GABA(B) receptor antagonist, SGS-742, is currently being tested as a potential therapeutic in an NIH phase II clinical trial (NCT02019667).
The GABA antagonist CGP-35348 (3-amino-propyl-(diethoxymethyl) phosphinic acid) has been used in Aldh5a1-/- mice with strong results. It has shown to reduce the frequency of absence seizures, though there have been some cases in which it worsened convulsive seizures.
The primary treatment method for fatty-acid metabolism disorders is dietary modification. It is essential that the blood-glucose levels remain at adequate levels to prevent the body from moving fat to the liver for energy. This involves snacking on low-fat, high-carbohydrate nutrients every 2–6 hours. However, some adults and children can sleep for 8–10 hours through the night without snacking.
Carnitor - an L-carnitine supplement that has shown to improve the body's metabolism in individuals with low L-carnitine levels. It is only useful for Specific fatty-acid metabolism disease.
It has been suggested that a possible method of treatment for histidinemia is through the adoption of a diet that is low in histidine intake. However, the requirement for such dietary restrictions is typically unnecessary for 99% of all cases of histidinemia.
CTD is difficult to treat because the actual transporter responsible for transporting creatine to the brain and muscles is defective. Studies in which oral creatine monohydrate supplements were given to patients with CTD found that patients did not respond to treatment. However, similar studies conducted in which patients that had GAMT or AGAT deficiency were given oral creatine monohydrate supplements found that patient’s clinical symptoms improved. Patients with CTD are unresponsive to oral creatine monohydrate supplements because regardless of the amount of creatine they ingest, the creatine transporter is still defective, and therefore creatine is incapable of being transported across the BBB. Given the major role that the BBB has in the transport of creatine to the brain and unresponsiveness of oral creatine monohydrate supplements in CTD patients, future research will focus on working with the BBB to deliver creatine supplements. However, given the limited number of patients that have been identified with CTD, future treatment strategies must be more effective and efficient when recognizing individuals with CTD.
A high-protein diet can overcome the deficient transport of neutral amino acids in most patients. Poor nutrition leads to more frequent and more severe attacks of the disease, which is otherwise asymptomatic. All patients who are symptomatic are advised to use physical and chemical protection from sunlight: avoid excessive exposure to sunlight, wear protective clothing, and use chemical sunscreens with a SPF of 15 or greater. Patients also should avoid other aggravating factors, such as photosensitizing drugs, as much as possible. In patients with niacin deficiency and symptomatic disease, daily supplementation with nicotinic acid or nicotinamide reduces both the number and severity of attacks. Neurologic and psychiatric treatment is needed in patients with severe central nervous system involvement.
Supplementary "protein substitute" formulas are typically prescribed for people PKU (starting in infancy) to provide the amino acids and other necessary nutrients that would otherwise be lacking in a low-phenylalanine diet. Tyrosine, which is normally derived from phenylalanine and which is necessary for normal brain function, is usually supplemented. Consumption of the protein substitute formulas can actually reduce phenylalanine levels, probably because it stops the process of protein catabolism from releasing Phe stored in the muscles and other tissues into the blood. Many PKU patients have their highest Phe levels after a period of fasting (such as overnight), because fasting triggers catabolism. A diet that is low in phenylalanine but does not include protein substitutes may also fail to lower blood Phe levels, since a nutritionally insufficient diet may also trigger catabolism. For all these reasons, the prescription formula is an important part of the treatment for patients with classic PKU.
The oral administration of tetrahydrobiopterin (or BH4) (a cofactor for the oxidation of phenylalanine) can reduce blood levels of this amino acid in some people. Most people, however, have little or no benefit.
Tentative evidence supports dietary supplementation with large neutral amino acids (LNAAs). The LNAAs (e.g. leu, tyr, trp, met, his, ile, val, thr) may compete with phe for specific carrier proteins that transport LNAAs across the intestinal mucosa into the blood and across the blood–brain barrier into the brain. It use is really only indicated in adults who will not follow an appropriate diet.
Another interesting treatment strategy for is casein glycomacropeptide (CGMP), which is a milk peptide naturally free of Phe in its pure form CGMP can substitute the main part of the free amino acids in the PKU diet and provides several beneficial nutritional effects compared to free amino acids. The fact that CGMP is a peptide ensures that the absorption rate of its amino acids is prolonged compared to free amino acids and thereby results in improved protein retention and increased satiety compared to free amino acids. Another important benefit of CGMP is that the taste is significantly improved when CGMP substitutes part of the free amino acids and this may help ensure improved compliance to the PKU diet.
Furthermore, CGMP contains a high amount of the phe lowering LNAAs, which constitutes about 41 g per 100 g protein and will therefore help maintain plasma phe levels in the target range.
The conversion of tryptophan to serotonin and other metabolites depends on vitamin B. If tryptophan catabolism has any impact on brain glutaric acid and other catabolite levels, vitamin B levels should be routinely assayed and normalized in the course of the treatment of GA1.
Dietary control may help limit progression of the neurological damage.
HMG-CoA reductase inhibitors have been examined as treatment for SLOS. Given that this catalyzes the rate-limiting step in cholesterol synthesis, inhibiting it would reduce the buildup of toxic metabolites such as 7DHC. Simvastatin is a known inhibitor of HMG-CoA reductase, and most importantly is able to cross the blood–brain barrier. It has been reported to decrease the levels of 7DHC, as well as increase the levels of cholesterol. The increased cholesterol levels are due to simvastatin's effect on the expression of different genes. Simvastatin increases the expression of "DHCR7", likely leading to increased activity of DHCR7. It has also been shown to increase the expression of other genes involved in cholesterol synthesis and uptake. However, these benefits are dependent on the amount of residual cholesterol synthesis. Because some individuals possess less severe mutations and demonstrate some amount of DCHR7 activity, these people benefit the most from simvastatin therapy as they still have a partially functioning enzyme. For individuals that show no residual DCHR7 activity, such as those homozygous for null alleles or mutations, simvastatin therapy may actually be toxic. This highlights the importance of identifying the specific genotype of the SLOS patient before administering treatment. It is still unknown if simvastatin will improve the behavioural or learning deficits in SLOS.
Treatment for all forms of this condition primarily relies on a low-protein diet, and depending on what variant of the disorder the individual suffers from, various dietary supplements. All variants respond to the levo isomer of carnitine as the improper breakdown of the affected substances results in sufferers developing a carnitine deficiency. The carnitine also assists in the removal of acyl-CoA, buildup of which is common in low-protein diets by converting it into acyl-carnitine which can be excreted in urine. Though not all forms of methylmalonyl acidemia are responsive to cobalamin, cyanocobalamin supplements are often used in first line treatment for this disorder. If the individual proves responsive to both cobalamin and carnitine supplements, then it may be possible for them to ingest substances that include small amounts of the problematic amino acids isoleucine, threonine, methionine, and valine without causing an attack.
A more extreme treatment includes kidney or liver transplant from a donor without the condition. The foreign organs will produce a functional version of the defective enzymes and digest the methylmalonic acid, however all of the disadvantages of organ transplantation are of course applicable in this situation. There is evidence to suggest that the central nervous system may metabolize methylmalonic-CoA in a system isolated from the rest of the body. If this is the case, transplantation may not reverse the neurological effects of methylmalonic acid previous to the transplant or prevent further damage to the brain by continued build up.
Currently, the most common form of treatment for SLOS involves dietary cholesterol supplementation. Anecdotal reports indicate that this has some benefits; it may result in increased growth, lower irritability, improved sociability, less self-injurious behaviour, less tactile defensiveness, fewer infections, more muscle tone, less photosensitivity and fewer autistic behaviours. Cholesterol supplementation begins at a dose of 40–50 mg/kg/day, increasing as needed. It is administered either through consuming foods high in cholesterol (eggs, cream, liver), or as purified food grade cholesterol. Younger children and infants may require tube feeding. However, dietary cholesterol does not reduce the levels of 7DHC, cannot cross the blood–brain barrier, and does not appear to improve developmental outcomes. One empirical study found that cholesterol supplementation did not improve developmental delay, regardless of the age at which it began. This is likely because most developmental delays stem from malformations of the brain, which dietary cholesterol cannot ameliorate due to its inability to cross the blood–brain barrier.
PKU is not curable. However, if PKU is diagnosed early enough, an affected newborn can grow up with normal brain development by managing and controlling phenylalanine ("Phe") levels through diet, or a combination of diet and medication.
Due to neuroferritinopathy’s genetic etiology, the disorder is not currently curable. Furthermore, progression of the disorder is unable to be effectively halted. Therefore current treatment focuses on managing symptoms of the disorder.
No medication is available to treat all symptoms. Botox has been shown to help with focal dystonia. The dopamine depleter Tetrabenazine shown to help with involuntary movements. Symptoms affecting movement (dystonia) have also been treated with L-Dopa, orphenadrine, benzhexol, sulpiride, diazepam, clonazepam, and deanol. Parkinsonian symptoms were not decreased by L-Dopa. Iron supplements should be avoided.
The most commonly effective treatment is clonazepam, which leads to the increased efficacy of another inhibitory neurotransmitter, GABA. There are anecdotal reports of the use of Levetiracetam in genetic and acquired hyperekplexia. During attacks of hypertonia and apnea, the limbs and head may be flexed towards the trunk in order to dissipate the symptoms. This is named the Vigevano maneuver after the doctor who invented it.
Because HFM is a rare disorder, there are no studies that define its optimal treatment. Correction of the systemic folate deficiency, with the normalization of folate blood levels, is easily achieved with high doses of oral folates or much smaller doses of parenteral folate. This will rapidly correct the anemia, immune deficiency and GI signs. The challenge is to achieve adequate treatment of the neurological component of HFM. It is essential that the folate dose is sufficiently high to achieve CSF folate levels as close as possible to the normal range for the age of the child. This requires close monitoring of the CSF folate level. The physiological folate is 5-methyltetrahydrofolate but the oral formulation available is insufficient for treatment of this disorder and a parenteral form is not available. The optimal folate at this time is 5-formyltetrahydrofolate which, after administration, is converted to 5-methyltetrahydrofolate. The racemic mixture of 5-formyltetrahydrofolate (leucovorin) is generally available; the active S-isomer, levoleucovorin, may be obtained as well. Parenteral administration is the optimal treatment if that is possible. Folic acid should not be used for the treatment of HFM. Folic acid is not a physiological folate. It binds tightly to, and may impede, FRα-mediated endocytosis which plays an important role in the transport of folates across the choroid plexus into the CSF (see above). For a further consideration of treatment see GeneReviews.
As there appeared to be a connection with PED and mutated GLUT1 transporters a possible treatment was looking at changing patients diets. A common treatment for another disorder with a mutated GLUT1 transporter is the ketogenic diet. The diet is a strict 3:1 ratio of fat (3) to protein and carbohydrates (1). This diet is thought to help restore the unbalance created by the decreased amount of glucose in the brain caused by the faulty GLUT1 transporter. This diet was administered to three patients who had been screened and found to have mutation in their SLC2A genes coding for GLUT1 and were experiencing PED symptoms. All three showed benefit from this treatment and a reduction in their PED episodes. They were able to exercise and run long distances for the first time in their lives. No other studies have been performed using this diet as many patients feel the advantages of the diet do not outweigh its disadvantages.
As some cases have noted that patients were able to alleviate or lessen their PED attacks with a sugary snack, another diet that was tried on patients was one rich in carbohydrates with additional frequent carbohydrate-containing snacks. Four patients with reported PED symptoms were put on this diet but no observable improvements were noted and in fact one patient even complained of worsening symptoms.
Additionally it has been observed that levodopa may reduce some symptoms associated with PED. This may demonstrate that PED is a precursor to Parkinson's disease. Acetazolamide was beneficial to some patients, but also worsened symptoms in others. Additionally, a modified version of the Atkin's diet helped to regulate glucose levels in the CSF. Patients with PED associated with insulinomas appeared to have symptoms resolved after consuming sugary drinks. Currently, there are no drugs that are particularly useful in completely curing all symptoms.
Since phytanic acid is not produced in the human body, individuals with Refsum disease are commonly placed on a phytanic acid-restricted diet and avoid the consumption of fats from ruminant animals and certain fish, such as tuna, cod, and haddock. Grass feeding animals and their milk are also avoided. Recent research has shown that CYP4 isoform enzymes could help reduce the over-accumulation of phytanic acid "in vivo". Plasmapheresis is another medical intervention used to treat patients. This involves the filtering of blood to ensure there is no accumulation of phytanic acid.
No cures for lysosomal storage diseases are known, and treatment is mostly symptomatic, although bone marrow transplantation and enzyme replacement therapy (ERT) have been tried with some success. ERT can minimize symptoms and prevent permanent damage to the body. In addition, umbilical cord blood transplantation is being performed at specialized centers for a number of these diseases. In addition, substrate reduction therapy, a method used to decrease the production of storage material, is currently being evaluated for some of these diseases. Furthermore, chaperone therapy, a technique used to stabilize the defective enzymes produced by patients, is being examined for certain of these disorders. The experimental technique of gene therapy may offer cures in the future.
Ambroxol has recently been shown to increase activity of the lysosomal enzyme glucocerebrosidase, so it may be a useful therapeutic agent for both Gaucher disease and Parkinson's disease. Ambroxol triggers the secretion of lysosomes from cells by inducing a pH-dependent calcium release from acidic calcium stores. Hence, relieving the cell from accumulating degradation products is a proposed mechanism by which this drug may help.
Courses of treatment for children with is dependent upon the severity of their case. Children with OHS often receive physical and occupational therapy. They may require a feeding tube to supplement nourishment if they are not growing enough. In an attempt to improve the neurological condition (seizures) copper histidine or copper chloride injections can be given early in the child’s life.
However, copper histidine injections have been shown ineffective in studies of copper metabolic-connective tissue disorders such as OHS.
Response to treatment is variable and the long-term and functional outcome is unknown. To provide a basis for improving the understanding of the epidemiology, genotype/phenotype correlation and outcome of these diseases their impact on the quality of life of patients, and for evaluating diagnostic and therapeutic strategies a patient registry was established by the noncommercial International Working Group on Neurotransmitter Related Disorders (iNTD).
For individuals prescribed anti-anxiety medications such as Alprazolam (Xanax), caffeine can introduce further problems by increasing rates of cytotoxicity and cell death by necrosis. This leads to these medications being essentially ruled out as viable treatments for caffeine-induced anxiety. Due to caffeine’s negative interaction with anti-anxiety medications such as benzodiazepines, treatments for caffeine-induced anxiety disorder tend to focus on abstinence from or a reduction of caffeine intake and behavioral therapy. Some doctors may recommend a continuance of caffeine consumption but with the provision that the patient actively takes note of physiological changes that happen after caffeine intake. The goal of this approach is to help patients better understand the effects of caffeine on the body and to distinguish threatening symptoms from normal reactions.
In ruminant animals, the gut fermentation of consumed plant materials liberates phytol, a constituent of chlorophyll, which is then converted to phytanic acid and stored in fats. Although humans cannot derive significant amounts of phytanic acid from the consumption of chlorophyll present in plant materials, it has been proposed that the great apes (bonobos, chimpanzees, gorillas, and orangutans) can derive significant amounts of phytanic acid from the hindgut fermentation of plant materials.