Pubmed du 03/12/09

vendredi 4 décembre 2009

1. Grigorenko EL. Pathogenesis of autism : a patchwork of genetic causes. Future Neurol ;2009 ;4(5):591-599.

Autism spectrum disorders (ASDs) are relatively infrequent but are devastating developmental conditions characterized by marked deficiencies in social, communicative and other behavioral domains. It has been known for a substantial period of time that these disorders are genetic in nature. However, elucidating the specific mechanisms of these disorders has been difficult. A major reason for such difficulty is the recognized genetic heterogeneity of ASDs. Specifically, many genetic mechanisms related to structural variations in the genome have been reported as possible genetic causes of these disorders. This review briefly exemplifies these genetic mechanisms, presents a concise overview of the evidence for the genetic basis of ASDs and provides an appraisal of the specific structural genetic variants thought to contribute to the pathogenesis of these complex disorders.

2. Lazarev VV, Pontes A, Mitrofanov AA, Deazevedo LC. Interhemispheric asymmetry in EEG photic driving coherence in childhood autism. Clin Neurophysiol ;2009 (Nov 30)

OBJECTIVE : Examination of the EEG photic driving coherence during intermittent photic stimulation in autistic patients with relatively intact verbal and intellectual functions in order to enhance the likely latent interhemispheric asymmetry in neural connectivity. METHODS : Fourteen autistic boys, aged 6-14years, free of drug treatment, with I.Q. 91.4+/-22.8, and 19 normally developing boys were subject to stimulation of 12 fixed frequencies of 3-27Hz. The number of high coherent connections (HCC) (magnitude squared coherence >0.6-0.8) was estimated among 7 leads in each hemisphere. RESULTS : In contrast to the spectral characteristics showing the right hemisphere deficit in the photic driving reactivity, the number of HCC differentiated the groups only in the left hemisphere where it was higher in autistics at the EEG frequencies corresponding to those of stimulation at 6-27Hz without asymmetry at other frequencies, the left-side prevalence increasing with frequency. No asymmetry was observed in the resting state. CONCLUSIONS : Spectral and coherence characteristics of the EEG photic driving show different aspects of latent abnormal interhemispheric asymmetry in autistics : the right hemisphere "hyporeactivity" and potential "hyperconectivity" of likely compensatory nature in the left hemisphere. SIGNIFICANCE : The EEG photic driving can reveal functional topographic alterations not present in the spontaneous EEG.

3. Mazefsky C. Erratum to : Deborah Lipsky, Will Richards : Managing Meltdowns : Using the S.C.A.R.E.D Calming Technique with Children and Adults with Autism : Jessica Kingsley, Philadelphia, PA, 2009, 80 pp., ISBN 978-1-84310-908-2. $14.95 (paper). J Autism Dev Disord ;2009 (Dec 2)

4. Mrozek-Budzyn D, Kieltyka A, Majewska R. Lack of Association Between Measles-Mumps-Rubella Vaccination and Autism in Children : A Case-Control Study. Pediatr Infect Dis J ;2009 (Dec 1)

OBJECTIVE :: The first objective of the study was to determine whether there is a relationship between the measles-mumps-rubella (MMR) vaccination and autism in children. The second objective was to examine whether the risk of autism differs between use of MMR and the single measles vaccine. DESIGN :: Case-control study. STUDY POPULATION :: The 96 cases with childhood or atypical autism, aged 2 to 15, were included into the study group. Controls consisted of 192 children individually matched to cases by year of birth, sex, and general practitioners. METHODS :: Data on autism diagnosis and vaccination history were from physicians. Data on the other probable autism risk factors were collected from mothers. Logistic conditional regression was used to assess the risk of autism resulting from vaccination. Assessment was made for children vaccinated (1) Before diagnosis of autism, and (2) Before first symptoms of autism onset. Odds ratios were adjusted to mother’s age, medication during pregnancy, gestation time, perinatal injury and Apgar score. RESULTS :: For children vaccinated before diagnosis, autism risk was lower in children vaccinated with MMR than in the nonvaccinated (OR : 0.17, 95% CI : 0.06-0.52) as well as to vaccinated with single measles vaccine (OR : 0.44, 95% CI : 0.22-0.91). The risk for vaccinated versus nonvaccinated (independent of vaccine type) was 0.28 (95% CI : 0.10-0.76). The risk connected with being vaccinated before onset of first symptoms was significantly lower only for MMR versus single vaccine (OR : 0.47, 95% CI : 0.22-0.99). CONCLUSIONS :: The study provides evidence against the association of autism with either MMR or a single measles vaccine.

5. Zalla T, Labruyere N, Clement A, Georgieff N. Predicting ensuing actions in children and adolescents with autism spectrum disorders. Exp Brain Res ;2009 (Dec 3)

6. Zhu XW, Pan H, Li MR, Bao XH, Zhang JJ, Wu XR. [Analysis of the parental origin of de novo MECP2 mutations and X chromosome inactivation in fifteen sporadic cases with Rett syndrome.]. Zhonghua Er Ke Za Zhi ;2009 (Aug) ;47(8):565-569.

OBJECTIVE : Rett syndrome (RTT) is a neurodevelopmental disorder occurring almost exclusively in females as sporadic cases due to de novo mutations in the methyl-CpG-binding protein 2 gene (MECP2). Familial cases of RTT are rare and are due to X-chromosomal inheritance from a carrier mother. Recently, DNA mutations in the MECP2 have been detected in approximately 84.7% of patients with RTT in China. To explain the sex-limited expression of RTT, it has been suggested that de novo X-linked mutations occur exclusively in male germ cells resulting therefore only in affected daughters. To test this hypothesis, we have analyzed the parental origin of mutations and the XCI status in 15 sporadic cases with RTT due to MECP2 molecular defects. METHODS : Allele-specific PCR was performed to amplify a fragment including the position of the mutation. The allele-specific PCR products were sequenced to determine which haplotype contained the mutation. It was then possible to determine the parent of origin by genotyping the single nucleotide polymorphism (SNP) in the parents. The degree of XCI and its direction relative to the X chromosome parent of origin were measured in DNA prepared from peripheral blood leucocytes by analyzing CAG repeat polymorphism in the androgen receptor gene (AR). RESULTS : Except for 2 cases who had a frameshift mutation ; all the remaining 13 cases had a C—>T transition mutation. Paternal origin has been determined in all cases with the C—>T transition mutation. For the two frameshift mutations, paternal origin has been determined in one case and maternal origin in the other. The frequency of male germ-line transmission in mutations is 93.3%. Except for 2 cases who were homozygotic at the AR locus, of the remaining 13 cases, 8 cases had a random XCI pattern ; the other five cases had a skewed XCI pattern and they favor expression of the maternal origin allele. CONCLUSION : De novo mutations in sporadic RTT occur almost exclusively on the paternally derived X chromosome and that this is most probably the cause for the high female : male ratio observed in sporadic cases with RTT. Random XCI was the main XCI pattern in sporadic RTT patients. The priority inactive X chromosome was mainly of paternal origin.


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