1. Conroy J, Cochrane L, Anney RJ, Sutcliffe JS, Carthy P, Dunlop A, Mullarkey M, O’Hici B, Green AJ, Ennis S, Gill M, Gallagher L. {{Fine mapping and association studies in a candidate region for autism on chromosome 2q31-q32}}. {Am J Med Genet B Neuropsychiatr Genet};2009 (Jun 5);150B(4):535-544.
Autism (OMIM %209850) is a neurodevelopmental disorder with a strong genetic component. We previously reported a de novo rearrangement of chromosome 2q31 in a patient with autism [Gallagher et al. (2003); J Autism Dev Disord 33(1):105-108]. Further cytogenetic analysis revealed this to be a 46,XY, t(9;2)(q31.1;q32.2q31.3) translocation. Association mapping with microsatellite and SNP markers of this translocated region on 2q revealed association with markers in Integrin alpha-4 (ITGA4; GeneID 3676). ITGA4 was tested for association in a sample of 179 trio-based families. SNP markers in exons 16 and 17 showed evidence of association. Mutation screening revealed a G to A synonymous variation in the last nucleotide of exon 16 (rs12690517), significantly associated with autism in the Irish sample (OR = 1.6; P = 0.04). The location of this SNP at a putative splice donor site may affect the splicing of the ITGA4 protein. Haplotype analysis showed significant overtransmission of haplotypes surrounding this marker. These markers were investigated in two additional samples, 102 families from Vanderbilt University (VT) (n = 102), and AGRE (n = 267). A non-significant trend towards overtransmission of the associated allele of rs12690517 in the Irish sample (OR = 1.2; P = 0.067) and haplotypes at the 3′ end of ITGA4 was observed in the AGRE sample. The VT sample showed association with markers and haplotypes across the gene, but no association with the rs12690517 marker or its surrounding haplotypes. The combined sample showed evidence of association with rs12690517 (OR = 1.3; P = 0.008) and surrounding haplotypes. The findings indicate some evidence for the role of ITGA4 as candidate gene for autism.
2. Fan X, Miles JH, Takahashi N, Yao G. {{Abnormal Transient Pupillary Light Reflex in Individuals with Autism Spectrum Disorders}}. {J Autism Dev Disord};2009 (Jun 5)
Computerized binocular infrared pupillography was used to measure the transient pupillary light reflex (PLR) in both children with autism spectrum disorders (ASDs) and children with typical development. We found that participants with ASDs showed significantly longer PLR latency, smaller constriction amplitude and lower constriction velocity than children with typical development. The PLR latency alone can be used to discriminate the ASD group from the control group with a cross-validated success rate of 89.6%. By adding the constriction amplitude, the percentage of correct classification can be further improved to 92.5%. In addition, the right-lateralization of contraction anisocoria that was observed in participants with typical development was not observed in those with ASDs. Further studies are necessary to understand the origin and implications of these observations. It is anticipated that as potential biomarkers, these pupillary light reflex measurements will advance our understanding of neurodevelopmental differences in the autism brain.
