Autism spectrum disorders (ASDs) affect 1% or more of American children. ASDs are characterized by defects in social behavior, including language delay, abnormal social interactions, and repetitive or stereotyped interests or behaviors. ASDs show a large genetic component, with estimates of heritability as high as 60- 90%. However, the extreme heterogeneity of ASD is a persistent hurdle to gene discovery, and known genetic causes account for less than 15% of diagnoses. Although high throughput sequencing (HTS) methods allow systematic analysis of genetic variation across the entire exome, or even the entire genome, the interpretation of this data faces analytical challenges that have by no means been solved. The use of consanguineous pedigrees, in which parents share ancestry, allows the identification of candidate genes that can then be analyzed more broadly in nonconsanguineous families. Consanguineous families 1] reduce the heterogeneity of ASD, 2] simplify HTS analysis and validation, and 3] provide genetic linkage evidence to support the validity of specific mutations in a single family. Preliminary data confirms that HTS in such pedigrees can efficiently identify, in an unbiased fashion, recessive genetic causes of ASD relevant to both consanguineous and nonconsanguineous cohorts of patients. This study will seek to enroll consanguineous families diagnosed with ASD, perform homozygosity mapping to locate regions of the genome likely to harbor the mutation that causes their ASD, and perform whole genome sequencing (WGS) on the affected individuals to identify candidate variants. Further, linkage and whole exome sequencing data that was generated on consanguineous families from previous studies will continue to be analyzed. This study will expand on the previous work by 1] Generating WGS data on normal controls to identify common alleles within Middle Eastern populations thus allowing swifter, more sensitive and ultimately cheaper analysis in this and many other Middle Eastern WGS studies;2] Generating relatively high throughput methods of functionally validating strong candidate genes discovered through WGS using yeast models, transformed somatic cell lines, and other model systems;and 3] Using RNAi to generate mouse models of candidate genes discovered in this study, and an ongoing neuronal activity-dependent gene study, to examine the effects of removing the genes on dendrite and dendritic spine morphology and synaptic activity. Recent studies suggest that, despite the high level of heterogeneity, there are common biochemical pathways associated with ASD. The findings from this study will be instrumental in the identification of the genes that make up these pathways, and provide potential pharmaceutical targets for the treatment of ASD.

Public Health Relevance

Autism and autism spectrum disorders (ASD) are a group of neurological conditions that affect 1% or more of American children and are characterized by impairment in the ability to communicate, form relationships, and respond appropriately to the environment. With 60-70% of autistic individuals having some degree of intellectual disability, and most requiring lifelong assistance, the financial costs to society are very high, while the emotional and psychological costs to family members cannot even be estimated. This study seeks to identify the genetic causes of ASD as well as to enhance our understanding of how the disease affects the developing brain, in order to develop better treatments.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
2R01MH083565-06
Application #
8297210
Study Section
Genetics of Health and Disease Study Section (GHD)
Program Officer
Addington, Anjene M
Project Start
2007-09-28
Project End
2017-07-31
Budget Start
2012-08-15
Budget End
2013-07-31
Support Year
6
Fiscal Year
2012
Total Cost
$850,815
Indirect Cost
$361,841
Name
Children's Hospital Boston
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
02115
Reiff, Rachel E; Ali, Bassam R; Baron, Byron et al. (2014) METTL23, a transcriptional partner of GABPA, is essential for human cognition. Hum Mol Genet 23:3456-66
De Rubeis, Silvia; He, Xin; Goldberg, Arthur P et al. (2014) Synaptic, transcriptional and chromatin genes disrupted in autism. Nature 515:209-15
Hu, Wen F; Chahrour, Maria H; Walsh, Christopher A (2014) The diverse genetic landscape of neurodevelopmental disorders. Annu Rev Genomics Hum Genet 15:195-213
McLean, Rebecca L; Johnson Harrison, Ashley; Zimak, Eric et al. (2014) Executive function in probands with autism with average IQ and their unaffected first-degree relatives. J Am Acad Child Adolesc Psychiatry 53:1001-9
Manzini, M Chiara; Xiong, Lan; Shaheen, Ranad et al. (2014) CC2D1A regulates human intellectual and social function as well as NF-?B signaling homeostasis. Cell Rep 8:647-55
Hanson, Ellen; Cerban, Bettina M; Slater, Chelsea M et al. (2013) Brief report: prevalence of attention deficit/hyperactivity disorder among individuals with an autism spectrum disorder. J Autism Dev Disord 43:1459-64
Yu, Timothy W; Chahrour, Maria H; Coulter, Michael E et al. (2013) Using whole-exome sequencing to identify inherited causes of autism. Neuron 77:259-73
Poduri, Annapurna; Evrony, Gilad D; Cai, Xuyu et al. (2013) Somatic mutation, genomic variation, and neurological disease. Science 341:1237758
Picker, Jonathan D; Walsh, Christopher A (2013) New innovations: therapeutic opportunities for intellectual disabilities. Ann Neurol 74:382-90
Chahrour, Maria H; Yu, Timothy W; Lim, Elaine T et al. (2012) Whole-exome sequencing and homozygosity analysis implicate depolarization-regulated neuronal genes in autism. PLoS Genet 8:e1002635

Showing the most recent 10 out of 17 publications