Association of the homeobox transcription factor gene ENGRAILED 2 with autistic disorder in Chinese children

Abstract

Background: Autism is a neurodevelopmental disorder with a strong genetic component. Previous studies have mapped the disease to chromosome 7q, where the homeobox transcription factor ENGRAILED 2 (EN2) gene is located. EN2 is specifically involved in patterning the region that gives rise to the cerebellum. In the present work, we carried out a case-control study to determine whether 2 intronic single-nucleotide polymorphisms (SNPs) of EN2 are a susceptibility to autism in a Han Chinese population. Method: We enrolled 184 cases of DSM-IV-TR diagnosed autistic disorder, 225 controls of unrelated healthy volunteers and 409 randomly selected controls from the community who lives in the adjacent geographical regions for this study. Two SNPs (rs1861972, rs1861973) at the EN2 gene that have been reported to be associated with autism underwent analysis among our studied cohorts. Both the UNPHASE and PHASE statistical programs were utilized for evaluating the association of EN2 SNPs with autism based on allelic and genotypic frequencies and haplotype compositions accompanied with the goodness-of-fit method of the χ2 test. The gender difference was also investigated by using 2-side Fisher's exact test treated as a covariate in logistic regression analysis. Results and Conclusion: Both the allelic and genotypic distributions of the 2 polymorphisms were concordant with Hardy-Weinberg equilibrium. Significant differences were found for cases versus community and overall controls. By using the UNPHASE and PHASE programs, the 2-marker haplotype A-C of EN2 was identified to have a protective effect for autism, indicating that the ethnic difference might confound the EN2 association with autism. Therefore, more EN2 gene association studies of Han Chinese populations are warranted to confirm this finding. Copyright © 2008 S. Karger AG.