Genetics, Detoxification and Autism By Vicki Kobliner, MS, RD, CD-N
frequency of autism in identical twins and the fact that children with autism are 10 times more likely to have a sibling with the disorder than typical children. However, it has been said that in the case of autism and many other chronic diseases, genes are the loaded gun and environment pulls the trigger. In other words, without the predis- position to autism which arises from genetic anomalies, the disorder could not present itself, but even with this genetic predisposition, a child may not become autistic unless environmental influences act upon these altered genes to cause further harm. While no single gene or environmental agent has been pinpointed as the cause of autism, research has identified a number of genetic anomalies that appear to play a role. A Single Nucleotide Polymorphism (called a SNP or “snip”) is a small genetic variation that can occur within a human being’s DNA sequence. Since children inherit a set of genes from each parent, a child may inherit a SNP from one or both parents. Although more than 99% of human DNA sequences are the same, these SNPs can have a major impact on how humans respond to diseases, environ- mental factors such as bacteria, viruses, toxins, and chemicals, as well as drugs and other therapies. Inheriting one normal gene and one SNP makes the gene less efficient, and inheriting a SNP from both parents has an even greater impact. The SNPs that have been identified in autistic children play important roles in managing natu- ral detoxification and energy production in the cells. When these genes are inefficient, or overwhelmed, neurological effects ensue.
A Glutathione Since the factors contributing to autism are multifactorial and
affect a variety of metabolic processes in the body, certain research- ers have devoted their studies not to a single gene or toxin, but to particular pathways which can be affected by the combination of ge- netics and environment. In 2004, researchers at Arkansas Children’s Hospital found that autistic children have lower levels of a critical detoxifying compound called glutathione than their typical peers. Glutathione is not only essential for trapping toxins and readying them for excretion, but is also a very powerful antioxidant. Reduced levels of this compound have far reaching effects on overall health. While the children studied had lowered levels of the active form of glutathione (called reduced glutathione), they also had increased quantities of oxidized glutathione, an inactive form that is less desir- able.
While there is as of yet no definitive answer as to why children with autism have less reduced glutathione, the evidence points to a combination of genetics, nutrition, and toxic exposure. The ability to express the gene for glutathione production can vary from one person to the next. For those with a less efficient form of the gene, glutathione reserves can be exhausted by increased exposure to chemicals, pesticides and other environmental insults. We take in these toxins on a daily basis through air, water and food, and they
26 Natural Nutmeg April 2012
utism is a complex neurodevelopmental disorder affected by a multitude of genetic and environmental influences. The strong genetic component is widely accepted due to the
are ingested, inhaled and even absorbed through the skin. In an increasingly toxic world, small children with inefficient glutathione expression can be overwhelmed by the body burden. An enzyme called MTHFR, which is necessary for processing folic acid, is a key factor in producing glutathione, and the gene that governs it is another piece of the glutathione/detoxification puzzle. Many children with autism have a less efficient form of the gene that codes for MTHFR, making it harder to produce glutathione. One way to get around this deficit is by increasing a more broken down form of folic acid called folinic acid. Since folinic acid is produced after the MTHFR enzyme has done its work, adding it directly bypasses the logjam that can occur when MTHFR cannot keep up with the de- mand. Mothers with the variant for MTHFR are more likely to have a child with autism than women who have two normal genes. In a recent study of families in Northern California, three genes were identified as risk factors for autism in children. When moms had a variant of MTHFR, as well as another gene called CBS, and when children have a SNP for a gene called COMT, risk of autism was increased. Greater risk also was identified in moms with gene variants who did not take prenatal vitamins. The CBS gene manages the production of the CBS compound,
which is required for producing glutathione at a different but equally important step in the process than MTHFR. It requires vitamin B6 to function, and increasing B6 can help this process along. The third gene, called COMT, does not affect glutathione, but is necessary for the production of dopamine and other neurotransmit- ters in the brain. Children with COMT variants were more likely to have autism whether or not their moms took a prenatal vitamin, but the risk was even higher when there was no vitamin support. The relationship between nutrition and detoxification cannot be
overemphasized. It is important that children on the autism spec- trum consume foods free of chemicals and pesticides, hormones and antibiotics, in order to limit their exposure to toxins. However, this is not the only way nutrition plays a role in detoxification. Another fac- tor that affects glutathione production is protein intake. Glutathione is made up of three different protein fragments called amino acids, so when there is limited protein in the diet, less glutathione can be produced. In the Arkansas study, children with autism had less cysteine,
which is one of the required amino acids. As we have already seen, B vitamins play a critical role in detoxification processes and gluta- thione production. Vitamin B12, folic acid and Vitamin B6 are major players in an elegant yet complex biochemical dance that changes food proteins into glutathione, so highly processed diets that are lacking in B vitamins put up yet another roadblock to normal elimi- nation of toxins.
Mitochondria
Another important area of exploration into the development and treatment of autism is the mitochondria – tiny energy producing en- gines at the core of our cells. Recent studies have identified a subset of children with autism who have what is called a mitochondrial
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