Autism and Chromosomes
A Background Report and Proposed Study into Autism
Julian
W. Addison - Authentic Science Research
Student
Mr. Carlos
Franco, Jr.; Director of Science
Research at Manhattan
Center for Science and Mathematics,
Science Department
Background
Autism is a Pervasive Developmental Disorder (PDD) that is characterized by severe and sustained impairment in social interaction, development of restricted and repetitive patterns of behavior, interests, and activities. These characteristics result in clinically significant impairment in social, occupational, or other important areas of functioning. Delays in language, cognition, self-help skills, or in adaptive behavior, other than social interaction. Prevalence, or predominance, is limited but it appears to be more common in males. Onset of the disorder is usually very young. (http://www.wpi.edu/~trek/aspergers.html)
Personal Interest
I became interested in studying about autism due to a personal and familial interest in the disorder. I have a godbrother who is an autistic child and as a way of getting in better touch with him as well as his mother. Also, I wanted a better understanding into a topic that is not discussed as a mainstream topic of conversation. Lastly, I am also a person who likes to work with children and to do scientific research, and this is an excellent opportunity to be able to do both.
Body
A. An Increase in Diagnoses Among Youth
In a study performed by Peter E. Tanguay et al. (1998) he set out to find a reason as to why there were a rapid increase in the number of autism cases being diagnosed. Simply, the goal of his study was to develop a tentative solution to the problem of over diagnoses of "autism spectrum disorders." He was able to come up with a system of tests that he was able to use to come up with three factors to classify subjects’ social communication skills. Of the ninety subjects to begin the study, sixty-three had an "autism spectrum disorder." Their results were grouped into the three factor domains and further examined. The conclusion reached was there was no correlation between age and IQ scores in any of the three domains. The paper’s discussion suggested some changes be made to the Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-iv, American Psychiatric Association [APA], 1994). Tanguay also said that changes should also be made in the new DSM and that the term PDDNOS (Pervasive Developmental Disorder Not Otherwise Specified) should be used to diagnose lesser forms of autism. Tanguay also mentioned that to diagnose autism the criteria set in the DSM-IV as well as the Autism Diagnostic Interview-Revised (ADI-R, Lord, Rutter, & Le Couteur, 1994) Autism Algorithm should be used together to come to an accurate diagnosis. Their work suggested that larger population studies should be done to come to more justifiable conclusions and that researchers should also rely on the ADI-R just as much as the DSM-IV.
B. Lack of Total Population Studies
A study done by Kadesjö et al. (1999) focused on what would be the benefits of a total population study. The goal of their work was to see if the number of seven-year-olds with autism and/or Asperger’s syndrome is increasing, decreasing, or remaining constant. To so this study Kadesjö et al. used a group of eight hundred and twenty-six (826) children; a group of 409 were examined individually and with at least one parent. Also one teacher was interviewed and a follow-up screening was preformed with a group of 365. This was 89 percent of the original group and the screening was performed four years (48 months) later. The results of their tests found that 60 in 10,000 children (0.60 %) had autistic disorder and 48 in 10,000 (0.48 %) had Asperger’s syndrome. This study needs to be performed with a larger population (this study’s: 826 children) but they believe that autism cases are not any larger than thirty years ago. The increase in Asperger’s syndrome cases was credited to a change in the symptom threshold for diagnosis. Kadesjö has suggested that a population 50 to 100 times larger than his should be examined.
C. Etiology
Much research is being done into the rates at which autism is developing but equal amounts of research is being done into finding the etiology, or origin of the disorder. The first question posed is whether or not the disorder is of genetic origin or does it form somewhere else. Konstantarears and Homatidis (1999) did a study into chromosomal abnormalities in children to prove that statement that the etiology is more genetic and that it is polymorphic. They reported that sex-linked conditions such as fragile X, contrary to earlier reports, is now presumed to account for no more than 5% of the cases (Bailey et al., 1996). However Mazzocco et al. (1997) did a study to observe the behaviors of girls with fragile X syndrome. In Konstantareas’ study out of 127 children, 8 had chromosomal abnormalities and notably two children had an abnormality at chromosome 15. One child also had fragile X and that was normal for the rate of 0-60 % that Mazzocco et al. reported on. Neither study could narrow that rate down any. Mazzocco’s study was solely based on the X chromosome but Konstantareas’ studied all of the chromosomes. Konstantareas’ study seemed to focus on chromosome 15 and Mazzocco’s study seemed to focus on the X chromosome. This brings up the debate about whether the body chromosomes or the sex chromosomes are more closely related to autism’s etiology. The answer may lie in the sex chromosomes because both studies document a high prevalence of autism in males. Females are also less likely to be diagnosed with autism or fragile X (Marrocco et al., 1997). In Marrocco et al. (1997) documented that a majority of males with fragile X have mental retardation (MR) and that many of those affected are males. Many autistic females also have some forms of MR as cited in both studies. Exploration into the autism-MR connection needs to be addressed.
D. Social Skills of Adults with Autistic Disorder, PDDNOS, and Mental Retardation
Njardvik et al. (1999) did a study comparing social skills of adults with autistic disorder, PDDNOS, and MR. All participants were diagnosed with profound mental retardation and participants in the autism and PDDNOS groups had been previously diagnosed using the Childhood Autism Rating Scale (CARS; Schopler, Reichler, & Renner, 1988) and record review. The diagnoses were later reconfirmed in this study be one of the authors and an independent rater. Social skills were assessed by using the Vineland Adaptive Behavior Scales (VABS; Sparrow, Balla, & Cicchetti, 1984) and the Matson Evaluation of Social Skills in the Severely Retarded (the MESSIER; Matson, 1995). Significant differences between the autism and mental retardation groups were found on both the VABS and the MESSIER. The PDDNOS group demonstrated better positive nonverbal social skills than the autism group but the mental retardation group was better than the PDDNOS group.
E. Parental Perspectives and Their Effects of Autism
Kasari et al. (1999) did a study that examined the effects of the child's diagnosis (either autism or Down syndrome), age, and current educational placement on parental perceptions toward inclusion for their child with disabilities. Parents of children with their respective diagnoses completed surveys regarding their opinions on their child's current educational placement, their desire for changing that current placement, and their views on inclusive education. Their results indicated that diagnosis, age, and current placement influenced parental opinion on the ideal educational placement for their child. Parents of children with Down syndrome were significantly more likely to endorse inclusion (full-time schooling with general education students) as the ideal educational program for their child whereas parents of children with autism were more likely to endorse mainstreaming (consistent part-time schooling with general education students). Parents of younger children and parents whose children were already placed in general education programs favored inclusion rather than parents of older children or students currently in special education.
Research Intentions
A. Problem(s) to be Addressed
I have three possible problem statements that I would like to do for my proposed research. First, which site is more closely related to the etiology of autism: chromosome 15 or the X chromosome? Second, what is the link between mental retardation and autism? Also, what role does mental retardation plays in individuals with autism? Lastly, are there any other possible chromosomal sites where the etiology of autism can be found?
B. Hypotheses
I also have corresponding hypotheses to match each problem. Firstly, many different studies have concluded that the etiology of autism comes from the chromosomes. The most discussed areas are chromosome 15 and the X chromosome. I want to use DNA karyotyping to prove my belief that the X chromosome is more closely related to the etiology of autism because of its higher prevalence in males. Secondly, some studies have proven that mental retardation is often associated with autism. I would like to investigate into what role mental retardation plays in individuals with autism. I believe that mental retardation of just often an effect of autism and that they are not connected and develop independently of each other. Lastly, although I believe that only two chromosomes play a role in the etiology of autism there may be other possible sites where it could possibly develop. I would like to examine other possible chromosomal sites for mutations in autistic individuals. However, I follow my first hypothesis stating that only two chromosomes could be possible for the etiology and that it is highly unlikely that any other chromosomal site is responsible for the development of autism.
C. Goals of Research
My goals of research are: (a) to find which of these cases is more prevalent in individuals with autism: those diagnosed with gene mutations on chromosome 15 or those diagnosed with fragile X syndrome; (b) to determine what role the sex chromosomes (X and Y) play in the etiology of autism and the higher frequency of males with the disorder; (c) to examine the behaviors of individuals with these specific mutations; (d) to detect what role mental retardation (MR) plays in individuals with autism; and finally (e) to investigate other possible chromosomal sites for mutations in autistic individuals.
References
American Psychiatric Association (1994). Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV). Washington, DC: American Psychiatric Association.
Asperger’s Syndrome. http://www.wpi.edu/~trek/aspergers.html
Bailey, A., Phillips, W., & Rutter, M. (1996). Autism: Towards an integration of clinical, genetic, neuropsychological, and neurobiological perspectives. Journal of the American Academy of Child and Adolescent Psychiatry, 26:499-503.
Kadesjö, B., Gillberg, C., & Hagberg, B. (1999). Brief Report: Autism and Asperger Syndrome in Seven-Year-Old Children: A Total Population Study. Journal of Autism and Developmental Disorders, 29:327-331.
Kasari, C., Freeman, S. F. N., Bauminger, N., Alkin, M. C. (1999). Parental Perspectives on Inclusion: Effects of Autism and Down Syndrome. Journal of Autism and Developmental Disorders, 29:297-305.
Konstantareas, M. M. & Homatidis, S. (1999). Chromosomal Abnormalities in a Series of Children with Autistic Disorder. Journal of Autism and Developmental Disorders, 29:275-285.
Lord, C., Rutter, M., & Le Couteur, A. (1994). Autism Diagnostic Interview-Revised: a revised version of a diagnostic interview for caregivers of individuals with possible pervasive developmental disorder. Journal of Autism and Developmental Disorders, 24:659-685.
Matson, J. L. (1995). Matson Evaluation of Social Skills for Individuals with Severe Retardation. Baton Rouge, LA: Scientific Publisher.
Mazzocco, M., Kates, W., Baumgardner, T., Freund, L., & Reiss, A. (1997). Autistic Behaviors Among Girls with Fragile X Syndrome. Journal of Autism and Developmental Disorders, 27:415-435.
Njardvik, U., Matson, J. L., & Cherry, K. E. (1999). A Comparison of Social Skills in Adults with Autistic Disorder, Pervasive Developmental Disorder Not Otherwise Specified, and Mental Retardation. Journal of Autism and Developmental Disorders, 29:287-295.
Schopler, E., Reichler, R. J., & Renner, B.R. (1988). The Childhood Autism Rating Scale. Los Angeles: Western Psychological Services.
Sparrow, S. S., Balla, D. A., & Cicchetti, D. V. (1984). Adaptive Behavior Scales. Interview edition, Survey form manual. Circle Pines, MN: American Guidance Service.
Tanguay, P., Robertson, J., & Derrick, A. (1998). A Dimensional Classification of Autism Spectrum Disorder by Social Communication Domains. Journal of the American Academy of Child & Adolescent Psychiatry, 37:271-277.
For information on my research on autism and all of the research that I done in the past please vist my school related site at www.fortunecity.com/campus/art/88/school.html or if you are just interested in my research study you can check out www.fortunecity.com/campus/art/88/scire.html to see how I am progressing. If you want to know more about me as a person visit my personal site, www.fortunecity.com/campus/art/88/index.html.