CHOP research points to brain's glutamate signaling in autism, ADHD, schizophrenia
A large new analysis of DNA from thousands of patients has uncovered several underlying gene networks with potentially important roles in autism. These networks may offer attractive targets for developing new autism drugs or repurposing existing drugs that act on components of the networks.
Furthermore, one of the autism-related gene pathways also affects some patients with attention-deficit hyperactivity disorder (ADHD) and schizophrenia—raising the possibility that a class of drugs may treat particular subsets of all three neurological disorders.
"Neurodevelopmental disorders are extremely heterogeneous, both clinically and genetically," said study leader Hakon Hakonarson, M.D., Ph.D., director of the Center for Applied Genomics at The Children's Hospital of Philadelphia (CHOP). "However, the common biological patterns we are finding across disease categories strongly imply that focusing on underlying molecular defects may bring us closer to devising therapies."
The study by Hakonarson and colleagues, appearing online today in Nature Communications, draws on gene data from CHOP's genome center as well as from the Autism Genome Project and the AGRE Consortium, both part of the organization Autism Speaks.
Autism spectrum disorders (ASDs), of which autism is the best known, are a large group of heritable childhood neuropsychiatric conditions characterized by impaired social interaction and communication, as well as by restricted behaviors. The authors note that recent investigations suggest that up to 400 distinct ASDs exist.
The current research is a genome-wide association study comparing more than 6,700 patients with ASDs to over 12,500 control subjects. It was one of the largest-ever studies of copy number variations (CNVs) in autism. CNVs are deletions or duplications of DNA sequences, as distinct from single-base changes in DNA.
The study team focused on CNVs within defective gene family interaction networks (GFINs)—groups of disrupted genes acting on biological pathways. In patients with autism, the team found three GFINs in which gene variants perturb how genes interact with proteins. Of special interest to the study group was the metabotropic glutamate receptor (mGluR) signaling pathway, defined by the GRM family of genes that affects the neurotransmitter glutamate, a major chemical messenger in the brain regulating functions such as memory, learning, cognition, attention and behavior.
Hakonarson's team and other investigators previously reported that 10 percent or more of ADHD patients have CNVs in genes along the glutamate receptor metabotropic (GRM) pathway, while other teams have implicated GRM gene defects in schizophrenia.
Based on these findings, Hakonarson is planning a clinical trial in selected ADHD patients of a drug that activates the GRM pathway. "If drugs affecting this pathway prove successful in this subset of patients with ADHD, we may then test these drugs in autism patients with similar gene variants," he said.
In ASDs and other complex neurodevelopmental disorders, common gene variants often have very small individual effects, while very rare gene variants exert stronger effects. Many of these genes with very rare defects belong to gene families that may offer druggable targets.
The three gene families found in the current study have notable functional roles. The CALM1 network includes the calmodulin family of proteins, which regulate cell signaling and neurotransmitter function. The MXD-MYC-MAX gene network is involved in cancer development, and may underlie links reported between autism and specific types of cancer. Finally, members of the GRM gene family affect nerve transmission, neuron formation, and interconnections in the brain—processes highly relevant to ASDs.
The functional activities identified in the current study are consistent with a recent multicenter study in which Hakonarson participated, published May 1 in the American Journal of Human Genetics. That study, led by scientists from Paris and Toronto, and using Autism Genome Project data, found hundreds of rare ASD-related gene variants converging on gene networks involved in neuronal signaling, synapse function and chromatin regulation (a biological process affecting gene expression). Many of the genes in these networks have been implicated in other developmental disorders besides autism.
"Even though our own study was large, it captures only about 20 percent of genes causing ASDs," said Hakonarson, who added that still larger studies are needed to further unravel the genetic landscape of autism. "However, strong animal data support an important role for the glutamate receptor pathway in socially impaired behaviors modeling ASDs. Because the GRM pathway seems to be a major driver in three diseases-- autism, ADHD and schizophrenia--there is a compelling rationale for investigating treatment strategies focused on this pathway."
The AGRE Consortium, a program of Autism Speaks, provided resources and data for this study. AGRE is supported in part by the National Institutes of Health (including grant MH081810).
"The impact of the metabotropic glutamate receptor and other gene family interaction networks on autism," Nature Communications, published online June 6, 2014. http://doi.org/10.1038/ncomms5074
About The Children's Hospital of Philadelphia: The Children's Hospital of Philadelphia was founded in 1855 as the nation's first pediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals and pioneering major research initiatives, Children's Hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program receives the highest amount of National Institutes of Health funding among all U.S. children's hospitals. In addition, its unique family-centered care and public service programs have brought the 535-bed hospital recognition as a leading advocate for children and adolescents. For more information, visit http://www.chop.edu.
John Ascenzi | Eurek Alert!
An evolutionary heads-up – The brain size advantage
22.05.2015 | Veterinärmedizinische Universität Wien
Endocrine disrupting chemicals in baby teethers
21.05.2015 | Goethe-Universität Frankfurt am Main
Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.
Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...
Development and implementation of an advanced automobile parking navigation platform for parking services
To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...
The world's first electrical car and passenger ferry powered by batteries has entered service in Norway. The ferry only uses 150 kWh per route, which...
On Tuesday, 19 May 2015 the research icebreaker Polarstern will leave its home port in Bremerhaven, setting a course for the Arctic. Led by Dr Ilka Peeken from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) a team of 53 researchers from 11 countries will investigate the effects of climate change in the Arctic, from the surface ice floes down to the seafloor.
RV Polarstern will enter the sea-ice zone north of Spitsbergen. Covering two shallow regions on their way to deeper waters, the scientists on board will focus...
Nanoengineers at the University of California, San Diego developed a gel filled with toxin-absorbing nanosponges that could lead to an effective treatment for skin and wound infections caused by MRSA (methicillin-resistant Staphylococcus aureus), an antibiotic-resistant bacteria. This "nanosponge-hydrogel" minimized the growth of skin lesions on mice infected with MRSA - without the use of antibiotics. The researchers recently published their findings online in Advanced Materials.
To make the nanosponge-hydrogel, the team mixed nanosponges, which are nanoparticles that absorb dangerous toxins produced by MRSA, E. coli and other...
20.05.2015 | Event News
18.05.2015 | Event News
12.05.2015 | Event News
22.05.2015 | Materials Sciences
22.05.2015 | Information Technology
22.05.2015 | Materials Sciences