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Genetics: Chromosome 11 deletion links autism, obesity

by  /  7 June 2011

Slim chance: Individuals carrying a deletion on chromosome 11 are overweight and have behavioral problems and, in some cases, are diagnosed with autism.

Deletions on a segment of chromosome 11 are associated with autism, attention problems and obesity, according to a study published in the June issue of the American Journal of Medical Genetics Part A1.

The region, 11p14.1, is on the short arm of the chromosome and includes six genes. Intriguingly, two of these, BDNF and LIN7C, are involved in neuron development and communication at the synapse, the junction between neurons.

Deletions in a nearby region, 11p13, are known to cause ‘Wilms tumor, aniridia, genitourinary anomalies, and mental retardation’ (WAGR) syndrome, characterized by intellectual disability and obesity.

To better understand the role of genes just outside of the WAGR region, Arthur Beaudet and colleagues identified four individuals carrying deletions of varying sizes that overlap at the six-gene region of 11p14.1.

After reviewing the individuals’ medical records, the researchers found that all four individuals have learning problems and are tall and severely overweight. Three of them have attention deficit hyperactivity disorder and two have been diagnosed with autism.

The findings suggest that a wider span of chromosome 11 is involved in obesity and intellectual disability, whereas the genes in the smaller 11p14.1 region contribute to social and communication deficits characteristic of autism. Further implicating BDNF in autism, another study found BDNF deletions in 76.5 percent of individuals with WAGR syndrome and autism, compared with 42.3 percent of individuals with WAGR but not autism2.

Studies of other chromosomal deletions have also tied autism to obesity. For example, the Prader-Willi syndrome deletion on chromosome 15 causes mental retardation, obesity and sometimes autism. Similarly, about three percent of people who are both obese and have developmental delays carry an autism-linked deletion on chromosomal region 16p.

References:

  1. Shinawi M. et al. Am. J. Med. Genet. A. 155, 1272-1280 (2011) PubMed
  2. Fischbach B.V. et al. Pediatrics 116, 984-988 (2005) PubMed

  • Anonymous

    It is interesting that this article is based on a study published by Arthur Beaudet. Beaudet was the first to pose the hypothesis that autism is heritable, but not inherited. Most of the single gene disorders that are associated with autism risk are the consequences of a de novo genetic mutation caused by a reproductive error (egg or sperm) or error early in fetal development, thus these reproductive errors may be in a sense heritable (egg or sperm) but that they are not inherited since the genetic mutation itself is not present in either parent.

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2427262/

    The two single gene disorders discussed in the article WAGR Syndrome and Prader-Willis Syndrome are almost always the consequence of a reproductive error and are not inherited.

    http://ghr.nlm.nih.gov/condition/wilms-tumor-aniridia-genitourinary-anomalies-and-mental-retardation-syndrome

    http://ghr.nlm.nih.gov/condition/prader-willi-syndrome

    Almost all of the single gene disorders linked to high autism risk are not inherited. Fragile X appears to be to follow a Mendelian pattern. However, among the single gene disorders linked to autism risk that are in most cases not inherited are Rhett Syndrome, Downs Syndrome, Tuberous Sclerosis, 16P mutation syndrome, Klinefelter Syndrome, Phelan McDermid Syndrome, Prader-Willis Syndrome, Angelman Syndrome, William Syndrome, Turner Syndrome and CHARGE Syndrome. The recurrence risk in these single gene disorders linked to autism risk that are the consequence of a de novo mutation are almost always no greater than general population risk.

    The design strategy followed by SFARI researchers and the NIH is forward looking in creating genetically engineered animals and working with an alliance with the pharmaceutical industry that may, or may not, produce new therapeutic interventions addressing the myriad of autism symptoms.

    In terms of prevention, equally important is taking a backwards looking strategy and understand the value of studying the causes of these de novo genetic mutations. It is known that parental age is linked to autism risk but in what way? Is there synergy between advanced parental age and environmental pathogens? Certainly X-irradiation has been found to cause de novo mutations and there are other environmental pathogens may, or may not, be linked to autism risk but science knows virtually nothing about the causes of de novo mutations. This is a profoundly neglected area of research.

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2788022/?tool=pubmed

  • Essilevy Colon

    This is really interesting I never hear nabout this until yesterday that the labs came and the tell me that I have the gene chromosome 11 duplicate and my daughter have too. He have autism, they tell me this can be the cause for her condition . I still try to get more information.

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