October 28, 2013 11:45 am Published by Francisco Monegro, Ph.D., M.D.
October 22, 2013 8:01 pm Published by Anne Denning, MA, BCBA, Director of Training
At the 17th Conference on “Advances in Autism” held October 2013 at the Icahn School of Medicine at Mount Sinai Hospital, Dr. Buxbaum and Dr. Reichenberg outlined the argument that autism is a behavioral defined complex neurodevelopmental disorder resulting from the combination of genetic and environmental factors. The critical issues discussed were: to what extent is autism genetic, what is the role of the environmental risk factors for autism, and to what degree can autism be due to the interactions between genes and environmental factors? How genetic factors compare to non-genetic factors?
Dr. Buxbaum stated that at this point we know three things about autism: a) Autism Spectrum Disorder (ASD) is defined by, “deficits in social interaction and the social use of language and presence of stereotypical mannerism”; b) ASD is highly genetic and the heritability has been estimated in 80-90%; and c) the genetic architecture of ASD includes many rare genetic variants with major effect in chromosome abnormalities.
In the human genomics, scientists have identified a large number of genetic variations associated with autism. According to Rosenberg and colleagues (2009) monozygotic twins have higher concordance rates than dizygotic twins. The concordance rates among monozygotic twins (MZ) for Autistic Disorder are estimated at approximately 77% to 86%, and for dizygotic twins (DZ) at about 40% to 50%. (The California Autism Twins Study (CATS), Hallmayer et al., 2011). The risk for siblings of individuals with autism is 2% to 8%, and rises to 12% to 20% if we also take into consideration siblings showing impairment in one or two symptom domains of autism. In support of this notion, the concordance rates for autism reach up to 90% in monozygotic twins and 10% in dizygotic twins (Rutter, 2000; Folstein and Rosen-Sheidley, 2001; Veenstra-Vanderweele et al., 2003; Won, et al. 2013).
Genetic factors might be mainly responsible for the occurrence of autism; however they are not solely responsible in all cases. There is some combination of autism-related genes and /or specific environmental factors that might act as triggers for the development of autism. The role of environmental factors in autism is somewhat a neglected area of research. One of the challenges is to understand the relationship between genetic variations and phenotype, since identical variations have been associated with autism and schizophrenia (Chaste & Leboyer 2012). Other unresolved issues are the two major hypotheses of the sex ratio (sex chromosomes and the role of hormonal influences in utero in the etiology of autism), where autism is more prevalent in males than females. Moreover, the overlap in which 65% to 75% of individuals with autistic disorder have an intellectual disability, is not clear. Two hypotheses have been proposed: individuals with autism and intellectual disabilities share common genetic bases, and the intellectual disability unmasks the limitation in the individual’s capacity for social reciprocity (Chaste & Leboyer, 2012). There is evidence that epigenetic dysregulation may be implicated in autism, such can be seen in the several syndromes associated with autism that are caused by mutations in genes. Epigenetics is defined as the non-permanent heritable changes that alter expression of genes without affecting primary DNA sequence itself, which considers the role of environment in this modulation of gene expression. Research data suggest that many environmental risk factors are interrelated and their identification and comparison might disclose a common scheme in autistic disorder (Grabrucker, 2012).
Furthermore, according to Lehti and colleagues (2013), environmental factors in connection with gene-environment interactions may influence the risk of autism. There are several potential environmental risk factors associated with autism such as advanced parental age (father >40 and mother >35), obstetric complications, viral or bacterial infection (influenza, rubella, and cytomegalovirus infections), disruption in the immune system, zinc homeostasis, dietary factors, lack of vitamin D, and being a second-generation immigrant (Grabrucker, 2012). Several studies conducted in Europe have shown that immigrants born outside Europe have an increased risk of having a child with autism. For instance, in Finland, children have an increased risk of autism if their mother or both parents are immigrants. The main prenatal and perinatal factors are maternal gestational diabetes, maternal bleeding and maternal medication. Exposure to certain medications during pregnancy, such as Selective Serotonin Reuptake Inhibitors (SSRI), use of valproate, as well as organophosphate insecticide, has shown to increase the risk of autism, especially if contact occurred during the first trimester (Schendel, 2013; Gardener, et al. 2009; Landrigan, 2010). These risk factors might cause brain morphological abnormalities, including altered cerebellar structures and reduced number of cranial motor neurons (Rodier et al., 1997; Ingram et al., 2000, Blattner, 1974; Grabrucker, 2012). The hypothesis of the MMR vaccine (measles, mumps, rubella) has been rejected for lack of scientific evidence of a causal relationship between thimerosal-containing vaccines and autism (Madsen, et al. 2002).
The appearance of a connection between autism-associated genes and environmental risk factors suggests that more studies concerning gene-environmental risk factors and multigenerational studies (autism across generations) are needed; these should also bring together analytic epidemiology, behavioral genetics and molecular epigenetic to continue solving the puzzle of the etiology of Autism Spectrum Disorder (ASD).
The Long Island Sibling Support Group hosted their annual Halloween Party. Before the fun commenced, group leaders reviewed some Halloween etiquette with siblings, as to ensure a safe and fun Halloween. We shared tips and practiced some fun activities for enjoying Halloween. The Long Island Parent and Sibling Group runs twice a month at our Long Island site in Baldwin.
It is free for parents and siblings of children diagnosed with autism. Click here
for more information and to view the schedule.
Here are some of our Halloween ideas…
- Wear costumes that can be seen.
- Bring a flashlight, glow stick, or reflective tape to place on your costume
- Make sure that you and your sibling can see with your mask on!
- Make sure you and your sibling do not trip over your costume.
- Practice putting on your costume. (New things can sometimes be scary for your brother or sister.)
Trick or Treat!
- Practice what to say and do when you go out Trick or Treating.
- Remind your sibling that you knock on someone’s door or ring their bell and say “Trick or Treat!“
- Practice holding your treat bag up to the door.
- Use this time to teach your sibling to have manners.
List examples of Halloween etiquette: