1. ¹Department of Human Genetics, Hebrew University, Jerusalem, Israel
2. ²Department of Child Psychiatry, Hadassah-Hebrew University Medical School, Jerusalem, Israel
3. ³Department of Psychology, Hebrew University, Jerusalem, Israel
4. ⁴Faculty of Mathematics, The Alexander Silberman Institute of Life Sciences, Faculty of Science, Hebrew University, Jerusalem, Israel
5. ⁵S Herzog Memorial Hospital, Jerusalem, Israel

Correspondence: Professor RP Ebstein, Department of Psychology, Scheinfeld Center of Human Genetics for the Social Sciences, Hebrew University, Jerusalem 91905, Israel. E-mail: ebstein@mscc.huji.ac.il

Received 22 February 2007; Revised 19 August 2007; Accepted 20 August 2007; Published online 25 September 2007.

Abstract

Evidence both from animal and human studies suggests that common polymorphisms in the oxytocin receptor (OXTR) gene are likely candidates to confer risk for autism spectrum disorders (ASD). In lower mammals, oxytocin is important in a wide range of social behaviors, and recent human studies have shown that administration of oxytocin modulates behavior in both clinical and non-clinical groups. Additionally, two linkage studies and two recent association investigations also underscore a possible role for the OXTR gene in predisposing to ASD. We undertook a comprehensive study of all 18 tagged SNPs across the entire OXTR gene region identified using HapMap data and the Haploview algorithm. Altogether 152 subjects diagnosed with ASDs (that is, DSM IV autistic disorder or pervasive developmental disorder—NOS) from 133 families were genotyped (parents and affected siblings). Both individual SNPs and haplotypes were tested for association using family-based association tests as provided in the UNPHASED set of programs. Significant association with single SNPs and haplotypes (global P-values <0.05, following permutation test adjustment) were observed with ASD. Association was also observed with IQ and the Vineland Adaptive Behavior Scales (VABS). In particular, a five-locus haplotype block (rs237897-rs13316193-rs237889-rs2254298-rs2268494) was significantly associated with ASD (nominal global P=0.000019; adjusted global P=0.009) and a single haplotype (carried by 7% of the population) within that block showed highly significant association (P=0.00005). This is the third association study, in a third ethnic group, showing that SNPs and haplotypes in the OXTR gene confer risk for ASD. The current investigation also shows association with IQ and total VABS scores (as well as the communication, daily living skills and socialization subdomains), suggesting that this gene shapes both cognition and daily living skills that may cross diagnostic boundaries.