by Eli Hatchwell, MD PhD

In two articles published in Nature in April 2009, researchers from the Center for Applied Genomics at the Children’s Hospital of Philadelphia report novel genetic findings in ASD. In the first paper, a search was conducted for common variants that might predispose to ASD in all affected individuals, while the second paper focused on the presence of rare genetic changes, confined to those with ASD.

The search for common variants in ASD has not been successful in the past but in April’s report, evidence was found for the likely role of a region of chromosome 5p14.1, which includes two genes, named Cadherin 9 and Cadherin 10, known to be involved in the way that nerve cells communicate with each other during development. While the effects uncovered were weak, the statistics are indicative of an important role for these genes and the region of the genome they inhabit. This discovery does not mean that a new diagnostic test will become available for ASD – rather, it yield insights into the molecular mechanisms that might be worthy of further study.

In a separate study from the same authors, a search was conducted for rare copy number variants (CNVs) that appear to be specific to ASD cases. In addition to confirming the presence of CNVs affecting genes already reported (including CNTN4, reported by Dr. Hatchwell in 2008), the study’s authors report the discovery of a set of genes that fall into 2 categories: genes that mediate neuronal communication (as above, although a distinct set were found) and genes that are involved in the modification of proteins prior to degradation (this class of genes was a novel finding for ASD).

In summary, these studies add to the knowledge of the causes of ASD, and further reinforce the notion that ASD represents a heterogeneous group of disorders for which no one cause is ever likely to be found.

Eli Hatchwell MD PhD, Director of the Genomics Core Facility and Associate Professor in Pathology, Stony Brook University Medical Center, NY is heading up the genetic component of Icare4autism’s International Autism Conference in Jerusalem in February, 2010. He just released the following report on new studies indicating evidence of novel genes in ASD.