1. Anderson BM, Schnetz-Boutaud NC, Bartlett J, Wotawa AM, Wright HH, Abramson RK, Cuccaro ML, Gilbert JR, Pericak-Vance MA, Haines JL. {{Examination of association of genes in the serotonin system to autism}}. {Neurogenetics};2009 (Jan 28)
Autism is characterized as one of the pervasive developmental disorders, a spectrum of often severe behavioral and cognitive disturbances of early development. The high heritability of autism has driven multiple efforts to identify genetic variation that increases autism susceptibility. Numerous studies have suggested that variation in peripheral and central metabolism of serotonin (5-hydroxytryptamine) may play a role in the pathophysiology of autism. We screened 403 autism families for 45 single nucleotide polymorphisms in ten serotonin pathway candidate genes. Although genome-wide linkage scans in autism have provided support for linkage to various loci located within the serotonin pathway, our study does not provide strong evidence for linkage to any specific gene within the pathway. The most significant association (p = 0.0002; p = 0.02 after correcting for multiple comparisons) was found at rs1150220 (HTR3A) located on chromosome 11 ( approximately 113 Mb). To test specifically for multilocus effects, multifactor dimensionality reduction was employed, and a significant two-way interaction (p value = 0.01) was found between rs10830962, near MTNR1B (chromosome11; 92,338,075 bp), and rs1007631, near SLC7A5 (chromosome16; 86,413,596 bp). These data suggest that variation within genes on the serotonin pathway, particularly HTR3A, may have modest effects on autism risk.
2. Frye RE, Beauchamp MS. {{Receptive language organization in high-functioning autism}}. {J Child Neurol};2009 (Feb);24(2):231-236.
One of the core defining components of autism is impairment in communication, typically manifested as a delay in speech development. To date, neuroimaging studies have shed limited light on the mechanisms behind delay in speech development in autism. We performed magnetoencephalographic-based auditory language mapping in 2 cases of high-functioning autism. Overall, 2 distinct characteristics were found, such as the use of atypical language pathways and cortical hyperexcitability. These neurophysiological findings parallel those reported in 2 other developmental disorders, developmental dyslexia and Rett syndrome. We discuss common mechanisms that may account for cognitive delays across these developmental disorders.
3. Johnson S, Marlow N. {{Positive Screening Results on the Modified Checklist for Autism in Toddlers: Implications for Very Preterm Populations}}. {J Pediatr};2009 (Jan 28)
4. Kuban KC, O’Shea TM, Allred EN, Tager-Flusberg H, Goldstein DJ, Leviton A. {{Positive Screening on the Modified Checklist for Autism in Toddlers (M-CHAT) in Extremely Low Gestational Age Newborns}}. {J Pediatr};2009 (Jan 28)
OBJECTIVE: To test the hypothesis that children born preterm are more likely to screen positive on the M-CHAT for an autism spectrum disorder. STUDY DESIGN: We compared the M-CHAT positive rate of those with cerebral palsy, cognitive impairment, and vision and hearing impairments to those without such deficits. RESULTS: Relative to children who could walk, the odds for screening positive on the M-CHAT were increased 23-fold for those unable to sit or stand independently and more than 7-fold for those requiring assistance to walk. Compared with children without a diagnosis of cerebral palsy, those with quadriparesis were 13 times more likely to screen positive, and those with hemiparesis were 4 times more likely to screen positive. Children with major vision or hearing impairments were 8 times more likely to screen positive than those without such impairments. Relative to those with a Mental Development Index (MDI) of >70, the odds for screening positive were increased 13-fold for those with an MDI of <55 and more than 4-fold for those with an MDI of 55 to 69. CONCLUSIONS: Major motor, cognitive, visual, and hearing impairments appear to account for more than half of the positive M-CHAT screens in extremely low gestational age newborns. Even after those with such impairments were eliminated, 10% of children-nearly double the expected rate-screened positive.
5. Ming X, Johnson WG, Stenroos ES, Mars A, Lambert GH, Buyske S. {{Genetic variant of glutathione peroxidase 1 in autism}}. {Brain Dev};2009 (Feb 3)
Genetic factors can contribute to autistic disorder (AD). Abnormal genes of oxidative stress pathways and increased oxidative stress have been reported in autism spectrum disorders. Polymorphisms of genes involved in glutathione metabolism, e.g. GSTP1 and GSTM1 are reportedly associated with autistic disorder. We investigated a GCG repeat polymorphism of a human glutathione peroxidase (GPX1) polyalanine repeat (ALA5, ALA6 and ALA7) in 103 trios of AD (probands and parents) using the transmission disequilibrium test. Significant transmission disequilibrium (p=0.044) was found in the overall transmission of the three alleles. The ALA6 allele was under transmitted (p=0.017). These results suggest that possessing this ALA6 allele may be protective for AD. Future study of interaction of the GPX1 GCG repeat and other gene polymorphisms such as the MnSOD ALA16 or the GPX1 Pro198Leu polymorphism in this cohort of AD families may shed light in whether the combination of the ALA6 allele with another polymorphism of antioxidant allele contributes to the increased oxidative stress in autism.
6. Nakashima N, Yamagata T, Mori M, Kuwajima M, Suwa K, Momoi MY. {{Expression analysis and mutation detection of DLX5 and DLX6 in autism}}. {Brain Dev};2009 (Feb 3)
Linkage analysis has reported the chromosomal region 7q21 to be related with autism. This region contains an imprinting region with MECP2-binding sites, and DLX5 is reported to be modulated by MECP2. DLX5 and adjacent DLX6 are homeobox genes working in neurogenesis. From these points, DLX5 and DLX6 are candidate genes for autism. Therefore, we analyzed the expression of DLX5 and DLX6, and also PEG10 as a control in the lymphoblasts of autistic spectrum disorder (ASD) patients by real-time PCR to identify potential abnormality of expression. And we also analyzed DLX5 and DLX6 on ASD patients for mutation by direct sequence. The expression level of DLX5 was not different between ASD and controls but was higher in four ASD patients compared to controls. Clinical features of these four patients were variable. DLX5 expression was biallelic in two ASD patients and two controls, indicating that DLX5 was not imprinted. There was no mutation in DLX5 in ASD. Although DLX5 was not likely to play major role in ASD, genes relating to DLX5 expression and downstream of DLX5 are considered to be candidate genes for some of the ASD patients. In DLX6, we detected a G656A base change (R219H) in two ASD patients who were male siblings. DLX6 may contribute to the pathogenesis of ASD.
