Autism Genetics Vs Environment

Is autism genetic, environmental or both?

The evidence continues to provoke and confound. The consensus from a group of studies concluded in the past six months is "both". But it's not as simple as that. Let's break it apart.

There is the multiplex version of autism (parents have multiple children with autism) in which several genes  are affected. This is the inherited type of autism.

The simplex version (parents have a single child with autism) breaks down into three types (but stay tuned, this will explode into a multitude of types very soon). First there are some rare inheritable disorders such as Rhett's and Fragile-X. These make up 8% of the multiplex type. Next there is a genetic version which is typically caused by mutated genes from aging parents. This is not inherited, but is still genetic. This, too, accounts for only 8% of the simplex cases. What is left is a  whopping 80+% of cases are not related to genetics. We used to think that autism 90% was genetic. One researcher called this new finding, "humbling".

As we all learned in biology, the environment of the mother's womb is instrumental in a baby's development. Researchers are now looking at the second trimester of pregnancy as being the key time that disruptions in development may occur. And high on the list of what they are looking at is a disruption of RNA functionality. RNA decodes the DNA strands in the body. If RNA is not performing its jobs correctly, huge changes can occur in the development of the child.

And now we come back to the miracle "cures" achieved with food supplements, changes in diet, hyper-oxygenation, etc. Is there a problem in specific children with the specific RNA mechanisms that ultimately create the proteins needed for food digestion, toxin removal and oxygenation? What is it about these remedies that affects not just the gastric system (for example), but affects the child's ability to communicate and to interact socially?

We also come back to the question: "What is autism and what are it's causes?" Will we continue to define it as a collection of symptoms: lack of social interaction, delayed/disrupted communication skills, etc.? Or will we define it in medical terms by the mechanisms that cause it. Stay tuned!

NIMH. (2011, 6 28). Autism Spring. Retrieved 10 31, 2011, from National Institute of Mental Health: http://www.nimh.nih.gov/about/director/2011/autism-spring.shtml

Lactase Enzyme Deficiency in Autism

A new study out of Harvard Medical School found that 58% of children with autism age 5 and younger are deficient in the lactase enzyme. Lactase is used to break down lactose in milk products.

The researchers found intestinal inflammation in 6% of the 199 patients. The report said, " Lactose inflammation or injury may contribute to abdominal discomfort, pain and observed aberrant behavior....most not identified by clinical history."

This number is higher (65%) in children over the age of 5. Boys are at 1.7 times greater risk than girls.

1.       Reference

          Kushak, R. I., Lauwers, G. Y., Winter, H. S., & Buie, T. M. (2011). Intestinal disaccharidase activity in patients with autism: Effect of age, gender and intestinal inflammation. Autism, 3: pp. 285-294.

More Genetics Vs Environment on Autism

Here are 4 recent studies showing a link from environmental factors including toxins to autism. Expect to see many, many more studies of this sort. Journal references are at the end of this posting.

1. Twin studies show that autism can be traced to both genetic and to environmental causes. (Hallmeyer, J., Cleveland, S., Torres, A. Phillips, J., Cohen, B., Torigoe, T., Miller, J., Fedele, A., Collins, J., Smith, K., Lotspeich, L., Croen, L., Ozonoff, S., Lajonchere, C., Grether, J., K., & Risch, N. (2011). Genetic heritability and shared environmental factors among twin pairs with autism. Arch Gen Psychiatry, published online July 4, 2011.)

2.  Women who are genetically at risk for foliate deficiency have a reduced risk for bearing a child with autism  if they take prenatal vitamins before and during pregnancy. (Schmidt, R. J., Hansen R. L., Hartiala J., Allayee H., Schmidt L. C., Tancredi D. J., Tassone F., Hertz-Picciotto I. (2011). Prenatal vitamins, one-carbon metabolism gene variants, and risk for autism. Epidemiology, 4,476-85.)

3. Women who take SSRIs before or during pregnancy (i.e. Proxac, Zolov, etc.) are at a 2% increased risk for bearing a child with autism.  (Croen, L. A., Grether, J. K., Yoshida, C. K., Odouli, R. & Hendrick, V. (2011). Antidepressant use during pregnancy and childhood autism spectrum disorders. Arch Gen Psychiatry, 73, 1-9.)

4. I may have mentioned previously that toxins including heavy metals, PCBs and jet fuel products are showing up in bodies of pregnant women - who typically carefully watch their health. Those elements are most likely in all of us. (Woodruff TJ, Zota AR, & Schwartz JM. (2011). Environmental chemicals in pregnant women in the United States:  NHANES 2003-2004. Environmental Health Perspectives, 6, 878-85.)