Factor analysis of repetitive behaviors in Autism as measured by the Y-BOCS.

The authors carried out a factor analysis of the Yale-Brown Obsessive-Compulsive Scale checklist at the category level in order to reduce the number of variables in this domain and ultimately identify possible endophenotypes; 181 children with autism were enrolled. The authors estimated a tetrachoric correlation matrix among the dichotomous symptom categories and then used exploratory and confirmatory factor analyses to identify a clinically meaningful factor structure for this correlation matrix. Their analysis supported a four-factor solution: obsessions, higher-order repetitive behaviors, lower-order repetitive behaviors, and hoarding.

Association analysis of the NrCAM gene in autism and in subsets of families with severe obsessive-compulsive or self-stimulatory behaviors.

Objectives: An autism susceptibility locus (AUTS1, MIM#608636) has been identified in chromosome 7q31. NrCAM is a candidate gene for AUTS1 because it is expressed in the brain and encodes a receptor involved in nervous system development. Polymorphisms in NrCAM have been reported to be associated with autism susceptibility and with substance abuse, implicating NrCAM in reward circuitry.

Family-based association study of TPH1 and TPH2 polymorphisms in autism.

The TPH1 and TPH2 genes encode the rate-limiting enzymes that control serotonin biosynthesis, and serotonin is clearly altered in autism. In the current study, eight SNPs in the TPH1 gene region and eight SNPs within the TPH2 gene were examined by family-based association tests in a large cohort of 352 families with autism and in clinically defined subsets of these families with either severe obsessive-compulsive behaviors (sOCB) or self-stimulatory behaviors (SSB). We found no evidence for association between autism and single SNPs or haplotypes of the TPH1 and TPH2 genes in the cohort of all families or in the sOCB and SSB subsets.

Lack of evidence for association of the serotonin transporter gene SLC6A4 with autism.

Background: The serotonin transporter (5-HTT) has long been considered likely to play a role in autism. Hyperserotonemia has been consistently found in a proportion of autistic patients, and the use of selective serotonin reuptake inhibitors (SSRIs) can have a positive effect in treating some symptoms of autism. Specific variants of the 5-HTT gene, SLC6A4, especially the insertion-deletion 5-HTTLPR promoter locus, have been found to modulate its expression and transporter function.