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Your Body’s Detoxification Pathways

Welcome back to the GPL-BLOG.  Over the past several weeks we’ve been discussing a lot of the environmental toxins that everyone is exposed to on a daily basis.  These toxins must be processed and detoxified.  Most of this is done in the liver through several different processes that include Cytochrome P450 (P450) biotransformation, glutathione conjugation, enzyme hydrolyzing, sulfation, and glucuronidation.

Detoxification is often referred to as a two stage process (phase 1 and phase 2) of metabolism (Figure 1).  Phase 1 metabolism involves the reduction or hydrolysis of the compound (usually caused by the addition of an oxygen molecule).  The addition of oxygen to a compound is referred to as oxidation.  This process is usually performed by the P450 enzymes.

Figure 1

The P450s are a family of enzymes that are found in numerous tissues throughout the body. However, a majority of these are found in the liver.  The P450s are important for the detoxification of many foreign substances, including environmental toxicants and medications.  The P450s are also important in controlling the levels of different molecules produced in the body such as the synthesis and breakdown of hormones, steroids, and multiple other molecules. 

In humans, 58 different P450s have been discovered.  However, only a subset of these is involved in the degradation of xenobiotics (chemicals that come from outside the body).  These enzymes have different substrates, which are determined by the activity pocket of each enzyme.   In regards to detoxification the most important P450s are Cyp1A2, Cyp2A6, Cyp2C9, Cyp2C19, Cyp2D6, Cyp2E1, and Cyp3A4.  Besides detoxification, these enzymes metabolize a majority of medications (figure 2).

Here are some important detoxification enzymes:

Figure 2

Cyp1A2 is important for the metabolism of polycyclic aromatic hydrocarbons (PAHs), which are found in cigarette smoke.  Other substrates include medications, aflatoxin B1, caffeine, and acetaminophen.  The major polymorphism is Cyp1A2*1K, which results in a decrease of activity.

Cyp2A6 is involved in the metabolism of nicotine.  Cyp2A6 is also involved in the metabolism of medications.  The major polymorphic alleles are Cyp2A6*4 and Cyp2A6*9 (which can have between 35% -70% activity depending on if you have one or two polymorphic copies). 

Cyp2C9 is involved with the metabolism of a large number of medications including NSAIDs, warfarin, and tamoxifen.  There are multiple polymorphisms that affect activity of the enzyme. 

Cyp2C19 is involved with the metabolism of multiple medications.  The most common are diazepam, omeprazole, and sertraline.  Cyp2c19 also metabolizes progesterone.   There are two major variants that result in loss of activity.  These are Cyp2C19*2 and Cyp2C19*3.

Cyp2D6 is involved with the metabolism of about 20% of drugs on the market.  It also metabolizes serotonin and neurosteroids.  There are five different polymorphisms that can lead to decreased activity.  Some of the classes of drugs that are metabolized by Cyp2D6 are antidepressants, SSRIs, opioids, and antipsychotics. 

Cyp2E1 is involved with the detoxification of many industrial pollutants, as well as carcinogens.  Cyp2e1 also metabolizes ethanol to acetaldehyde and acetate.  Cyp2e1 is also responsible for bioactivating a number of carcinogens, including cigarette smoke. 

Cyp3A4 is responsible for metabolizing more compounds than most other P450s.  It is responsible for metabolizing sex hormones, caffeine, statins, SSRIs, antifungals, antidepressants, and many other medications.  Some antibiotics can negatively affect its activity. Also, grapefruit and pomegranate juice have been shown to be potent inhibitors. 

Sulfur transferase is a phase 2 enzyme that adds sulfur groups to compounds in order to make them more water soluble and less reactive.  This process is used on a wide variety of toxic molecules including phenols, amines, acetaminophen, and food dyes.  Many chemicals that are able to become airborne are sulfated.  Patients with autism have been found to have impaired sulfation ability, which will make these individuals more sensitive to toxins.

Glutathione transferase is a phase 2 enzyme that catalyzes the conjugation of glutathione to substrates.  The addition of glutathione to toxins prevents these compounds from interacting with proteins in the body and allows them to be excreted via urine or bile.  There are a wide variety of compounds that are conjugated with glutathione.  A partial list includes pesticides, herbicides, carcinogens, acetaminophen, and mycotoxins.   

Glucuronosyltransferase (UGT) is another phase 2 enzyme that is responsible for the glucuronidation of many different toxic chemicals.  This process involves the addition of a glucuronosyl group to substrate molecules making them more polar and more easily excreted by the kidneys. 

Paraoxonase 1 (PON1) is an enzyme that is able to perform paraoxonase activity on substrates.  This enzyme is able to hydroylse and detoxify many different types of organophophate molecules.  PON1 is one of the major pathways that protects people from these types of compounds.  Mutations to PON1 could lead someone to be more sensitive to pesticides.  Infants do not have a lot of PON1 activity.  PON1 becomes active between birth and seven years of age. 

These are the major pathways that you should be aware of when you are thinking about detoxification.  Please see Table 1 to help you understand which pathway is mostly responsible for detoxifying these common toxicants.  Also see Figure 1 to help you understand what you can do to help support type 1 and type 2 detoxification pathways.  Detoxification of compounds by glutathione can be assisted by the supplementation of additional glutathione.  Next week I will discuss some additional methods to help with detoxification.  

Email gplblog@gpl4u.com if you have any questions about this blog post.

The Importance of Genetic Testing for Mental Health

Two weeks ago I talked about how we are starting to move into the age of personalized medicine.  Our goal at The Great Plains Laboratory is to determine what factors lead to chronic illnesses and what treatments may help.  Previously I discussed how the Organic Acids Test (OAT) and the GPL-SNP1000 DNA Sequencing Profile work well together to determine both the risk for and causes of many chronic illnesses and how useful these two tests are in helping practitioners develop individualized treatments.  Last week I specifically discussed the DNA methylation pathway, of the GPL-SNP1000.  This week I am going to go over the mental health pathway of the this same test.  I will talk about what genes are most important, some specific polymorphisms to be aware of, how the OAT can help diagnosis these disorders, and what treatments seem to work best. 

The two most important genes in this pathway are MAO-A (monoamine oxidase A) and COMT (catechol-o-methyltransferase) (Please see Figure 1). Both enzymes are required for metabolizing neurotransmitters critical to mental health. Mutations to either one can have serious consequences relating to how we think, feel, and interpret the world around us.

Figure 1

MAO-A
Monoamine oxidase A is important for the metabolism (breakdown) of biogenic amines such as the neurotransmitters dopamine, norepinephrine, and serotonin (figure 2).  Mutations to this gene have also been linked to depression, borderline personality disorder, and bipolar disorder. 

 

Figure 2

 

There are two different types of polymorphisms involved with MAO-A.  The first type, which is characterized by rs6323 , causes an increase in activity of the enzyme. Rapid metabolism resulting from this mutation causes depletion in the neurotransmitter. This depletion is directly related to the extent of the enzyme activity which can be determined on the Organic Acid test (OAT) by measuring the production of Homovanillic acid (HVA) and Vanillylmandelic acid (VMA) which are the end products of dopamine and epinephrine metabolism (see figure 1).  Patients who are rapid metabolizers will show an increase of HVA of VMA (Figure 3).  Such patients will have a depletion of these neurotransmitters which leads to multiple neurological diseases including depression. Treatment for these polymorphisms includes supporting the methylation pathway which helps to promote the cofactor required for neurotransmitter synthesis and providing neurotransmitter precursors such as tyrosine, B6 and 5-HTP.

Figure 3

A second type of polymorphism to MAO-A is one that decreases activity (rs72554632,  Gln296X), whichcauses a premature stop codon in the gene..  This polymorphismwill lead to a buildup of neurotransmitters, which can lead to the development of Brunner syndrome.  Brunner syndrome is characterized by a decrease of mental capabilities, increased impulsivity, mood swings, and sleep disorders. These individuals will have a decrease of HVA and VMA metabolites on the OAT. Without the benefit of genetic testing, these results could lead a practitioner to treat with neurotransmitter precursors. Increasing neurotransmitters for individuals with this type of mutation would actually exacerbate the condition. Treatments include decreasing the amine containing foods such as fish, cheese, and fruit, taking progesterone to increase MAO; taking inositol(which reduces 5HT2A serotonin receptor), taking riboflavin (increases MAO activity), or taking ginkgo, which has been shown to decrease aggressiveness in MAO-A deficient patients.

COMT
Catechol-O-methltransferase (COMT) is present in the body in two different forms.  The short form is called soluble catechol-O-methyltransferase (S-COMT).  The longer form is called membrane-bound catechol-O-methyltransferase (MB-COMT).   MB-COMT is mainly present in the nerves of the brain, while S-COMT is located in the liver, kidney, and blood.  In the brain, MB-COMT is responsible for degrading neurotransmitters called catecholamines, which include dopamine, epinephrine, and norepinephrine. Therefore the membrane bound form is believed to have a greater affect on mental health, though both forms may be implicated in disease since both are capable of metabolizing catecholamines.

GPL-SNP1000 analyzes six different SNPs for COMT.   Of these, the most extensively studied is a mutation to rs4680 (Val158Met). Despite the many studies available about this mutation, the scientific community is still at odds about the degree to which this mutation causes disease. What is known is that individuals with this mutation have lower activity of the enzyme.  Mutations to COMT will lead to dopamine and epinephrine not being broken down properly, which can be detected by a decrease in the HVA metabolite in the Organic Acids Test.

Figure 4

Interestingly, some individuals may benefit from increased dopamine while others may benefit from less. Dopamine functions differently depending on the area of the brain it is produced in and there are likely other mutation to this gene may also influence its function and expression. These interactions are still being investigated and are why GPL is looking beyond the most common mutation to help inform results.  Conditions associated with these mutations include OCD, depression, and schizophrenia.  Symptomatic patients may benefit from treatment aimed at promoting the enzyme function so that dopamine and epinephrine can be metabolized. This is a SAM dependant enzyme and methylation support can be helpful in patients with this mutation.

APOE
Apolipoprotein E (APOE) combines with lipids in the body to form lipoproteins.  Lipoproteins are responsible for packaging cholesterol and other lipids and carrying them through the bloodstream.  Like so many genes in the human body, this is not its only function. The ApoE protein is involved with more than was originally thought. In this case, it has a role in immune expression, cognitive function, and telomere regulation.  There are four different gene versions of APOE called e1 (the double mutant), e2 (rs7412), e3, and e4 (rs429358).  The most common version is e3, the most detrimental is e4

 Mutations to APOE can lead to an increased risk of developing Alzheimer’s disease. People who inherit even one copy of the APOE e4 allele have an increased risk of developing the disease. Certain mutations to this protein impair the ability of the body to phosphorylate NMDA (glutamate) receptors causing a reduction in activity (Glutamate receptors have been implicated in a number of neuropsychiatric disorders including depression, biopolar disorder, schizophrenia, and Autism (PMID: 12404584, 21315104). While this gene is being extensively studied for its role in Alzheimer’s disease, vulnerable patients may also be predisposed to other psychiatric disorders. (PMID: 25751510, 15557508). Patients with certain ApoE mutations may develop cognitive symptoms well before onset of Alzheimer’s disease (http://psycnet.apa.org/journals/neu/16/2/254/).  Patients with these polymorphisms should look for early signs of the development of Alzheimer’s disease.  Treatment with estrogen has demonstrated some encouraging results.

DAOA
The D-amino acid oxidase activator (DAOA) protein (also known as G72) is a 153 amino acid protein that localizes in the brain, spinal cord, and testis.  This protein is located in the endoplasmic reticulum and the mitochondria cellular compartments.   DAOA is a modulator of D-amino acid oxidase (DAO) activity.  If DAO is hyper activated it can result in a decrease in the D-serine level and hypo function of the NMDA receptor.  Overexpression of DAOA has been found in schizophrenics and those suffering from bipolar disorder.  Mutations to DAOA have been linked to a higher incidence of schizophrenia and bipolar disorder. 

It is important to remember that our genes influence our mental health and well being but do not necessarily determine the eventual outcome. There are countless factors that play an equal role in how we perceive the world including diet and lifestyle.   I believe that understanding the most common mutations and their function is very helpful in diagnosing, treating, and preventing different neurological disorders.  Using the GPL-SNP1000 test in combination with the OAT can further help determine the extent to which our genes are being expressed metabolically. The combination of these two tests can help bring about the best chance to achieve emotional health and physical well being.

Email gplblog@gpl4u.com if you have any questions about this blog post.

 

DNA Methylation Pathway

In my post last week I briefly talked about the methylation pathway, also called the MTHFR cycle and how disruptions in this pathway may appear on an Organic Acid Test (OAT).  Today, I will go more in-depth into this pathway. Since most practitioners have at least some knowledge of this its function, I’ve decided to focus on the more important polymorphisms (SNPs) common to these genes and on the treatments that work the best for these mutations.  Patients should talk to their healthcare practitioner before starting any treatment. 

The important role of methylation is gaining in popularity among functional medicine groups these days because mutations are quite common and lead to many different chronic conditions. Practitioners interested in treating the root cause of illness are especially interested in learning about this pathway because nucleotide synthesis, neurotransmitter function, detoxification, and numerous other processes are greatly improved once these mutations have been compensated for, leading to much better patient outcomes.

If you’re not already familiar, the methylation pathway is a process by which carbons are added onto folic acid from amino acids and redistributed onto other compounds throughout the body.  This process is responsible for the formation of methionine, S-Adenosyl methionine (SAM), and thymidylate monophosphate (dTMP).  Mutations in this pathway usually lead to the reduction of methionine which leads to the absence of S-adenosyl methionine (SAM). This compound facilitates virtually every methylation reaction in the body. These reactions include the promotion of several neurologically important agents, histamine breakdown, CoQ10 synthesis, and tissue-specific gene expression. The accumulation of homocysteine, which is caused by mutations in this pathway, has been directly linked to oxidative stress which influences multiple factors of disease.      

When we designed the GPL-SNP1000 test, we knew that most other genetic tests were only reporting about 35 SNPs of the common methylation pathway enzymes. When we did our literature research, we found 105 different methylation SNPs that could potentially cause health conditions and included all of these to provide a more useful tool for practitioners.

MTHFR

Methylenetetrahydrofolate reductase (MTHFR) is an enzyme that converts 5,10-methylenetetrahydrofolate to 5,methyltetrahydrofolate, which is the active form of folate.  Mutations in this gene cause the accumulation of homocysteine and a lack of available folate for cellular functions. Both of these factors have been linked to oxidative stress, vascular disease (including cardiovascular), neural tube defects, neurological disorders (including schizophrenia and bipolar disorder), cancer, preeclampsia, hypotonia, and seizures.  Common mutations are rs1801133 (C677T), rs1801131 (A1298C), and rs2274976 (G1793A).  The C677T polymorphism is present in about 39% of caucasians as heterozygotes and 17% as homozygotes.  Table 1 provides data on how much activity your MTHFR enzyme would possess with different combinations of the C677T and the A1298C.

TABLE 1

TABLE 1

Patients with polymorphisms in MTHFR may consider supplementing with methyl-B12 (also called methylcobalamin) and methyl-folate.  We recommended starting at a very low doses and building up.

MTR

Methionine synthase (MTR) is also known as 5-methyltetrahydrofolate-homocysteine methyltransferase.  This enzyme facilitates the transfer of a methyl group from 5-methyltetrahydrofolate to homocysteine using cobalamin (B12) and MTRR enzyme as a catalyst. The end products of this reaction are the amino acid methionine and the vitamin tetrahydrofolate.  Mutations in this gene lead to a lack of methionine and the accumulation of homocysteine in the body (hyperhomocysteinemia).  The pathological consequence of the gene mutation depends on how profoundly these methylation pathways are affected and the degree of homocysteine accumulation in the body.  The most common polymorphism is rs1805087 (A2756G), which most genetic tests do analyze.  However, we decided to look at seven different SNPs including the rs121913581 (R52Q) polymorphism.  This is a rare polymorphism; however it could dramatically affect the activity of patients with MTR polymorphisms, who should also consider methyl-B12, as well as S-adenosyl methionine (SAM) supplementation.  ).

MTRR

Methionine synthase reductase (MTRR) is also known as 5-methyltetrahydrofolate-homocysteine methyltransferase reductase.   MTRR is important for the methylation of cobalamin and subsequent activation of methionine synthase (MTR).  Mutations in this gene lead to a lack of methionine and the accumulation of homocysteine in the body (hyperhomocysteinemia). Some common mutations in this pathway are RS1801394 and RS10380.  Patients who are heterozygous for MTHFR mutations and concomitant mutations to MTRR have a greater loss of function and increased levels of homocysteine. Patients with MTRR polymorphisms should consider methyl-B12 and SAMe supplementation. 

AHCY

Adenosylhomocysteinase (AHCY) is also known as S-adenosylhomocysteine hydrolase.  AHCY is an enzyme involved in the degradation of the amino acid methionine.  AHCY converts the methionine substrate S-adenosylhomocysteine (SAH) to adenosine and homocysteine. This reaction is an important part of the regulation of methyl groups which are added to DNA, RNA, proteins, and lipids (fats).  Methyl groups help regulate what parts of the genome are active and control protein activity.  Mutations to the AHCY gene can cause methionine to accumulate in the blood, which is called hypermethioninemia (MET).  Two common mutations are Trp112X which causes tryptophan to be replaced with a premature stop signal and Tyr143Cys.  MET  can manifest in neurological problems, delays in motor skills, muscle weakness, and liver problems.  Patients with MET should consult with a dietician to avoid the amino acid methionine.

BHMT

Betaine-homocysteine methyltransferase (BHMT) and BHMT2 are the only enzymes that can metabolize betaine.  This reaction is considered the alternate or short route for methylation.  BHMT uses zinc as a co-factor to catalyze the transfer of a methyl group from betaine to homocysteine.  There are several mutations in the human population that decrease the activity of this enzyme.  BHMT mutations can result in fatty liver and hepatocellular (liver) carcinomas.  BHMT mutations in mothers increase the risk of Down syndrome for their children.  Patients with BHMT polymorphisms are recommended to take betaine and zinc.

CBS

Cystathione beta-synthase (CBS) is a pyridoxal-5’-phosphate (vitamin B6) dependent enzyme that converts L-serine and L-homocysteine into L-cystathionine.   L-cystathionine is later converted into the amino acid cysteine.  Mutations to the CBS gene are the most common cause of hereditary hyperhomocysteinemia.   The adverse effects of homocysteine accumulation in the body are related to the substitution of homocysteine for methionine in protein synthesis. The resulting complications include an increase in immune response, increase in cell death, and protein damage. The degree of homocysteinemia is relative to the mutation.  Hyperhomocysteinemia has been linked to multiple mutations to the CBS gene.  The most common of these are the Ile278Thr and the Gly307Ser, which cause homocysteine to build up in the blood.  Complications of hyperhomocysteinemia include mental retardation, seizures, and vascular disease. One of the most common causes of death for patients with homocystinuria (CBS deficiency) is heart attack.   Patients with CBS polymorphisms are recommended to take glutathione and B6.  There are reports that the CBS polymorphisms A360A (rs1801181) and N212N (rs2298758) can lead to an increase in CBS activity.  Some claim that these mutations lead to a buildup of ammonia and decrease in glutathione. Since ammonia is a very unstable compound that must be measured STAT for accurate results, the better marker for increased ammonia is orotic acid which is very stable and accumulates when excessive amines are filtered through the urea cycle. I recommend that patients with this mutation do an Organic Acid test (OAT) and look at marker 60 (orotic acid) for ammonia and markers 58-59 (Pyroglutamic and 2-hydroxybutyric acid) for glutathione synthesis and cysteine accumulation respectively.

SHMT1

Serine hydroxymethyltransferase (SHMT1) is important for linked reactions.  The first is the conversion of tetrahydrofolate to 5,10-methylenetetrahydrofolate.  The second is the conversion of L-serine to glycine.  It also has a role in mediating the synthesis of dTMP and SAM. It preferentially selects for dTMP biosynthesis which is the precursor to the nucleic acid thiamine. Mutations in this enzyme may cause elevations in uracil which can build up when dTMP synthesis in impaired.  Uracil is marker 40 in the OAT.  

SUOX

Sulfite oxidase (SUOX) is an enzyme that is located in the mitochondria of cells.  The enzyme oxidizes sulfite to sulfate.  The physiological damage that occurs as a result of enzyme deficiency may be due to the accumulation of toxic levels of sulfite, from the absence of sulfate, or both. Sulfite is a reactive product of cysteine metabolism found in high concentrations in the brain. Its toxicity is exacerbated by glutathione depletion. Sulfate plays an important role in detoxification and deactivation of toxic compounds. Sulfate deficiency has been linked to autism, Parkinson’s disease, and Alzheimer’s disease.  Individuals with SUOX genetic mutations may benefit from a reduction in dietary methionine and cysteine.

VDR

Vitamin D receptor (VDR) is a nuclear hormone receptor for vitamin D3.  Vitamin D3 interacts with this receptor to influence multiple biological activities by regulating gene transcription.  Vitamin D3 is associated with maintenance of calcium distribution. More recently, it has been implicated in inflammatory processes, vascular integrity, and collagen formation. Mutations in VDR have been linked to metabolic syndrome.  Individuals with VDR mutations have greater propensity for insulin insensitivity, higher triglycerides, and lower HDL levels.  Vitamin D receptor mutations can also lead to vitamin-D-dependent rickets type 2.  Patients with VDR polymorphisms are recommended to take 1000 units/day for children or 5000 units/day for adults. 

I hope this information is helpful.  I know many of these pathways can be very intimidating, but hopefully we can work together to produce useful treatment plans for everyone.  Next week I plan on talking about the mental health genes MAO and COMT.

Email gplblog@gpl4u.com if you have any questions about this blog post.