Pubmed du 17/11/09

mardi 17 novembre 2009

1. Bebbington A, Percy A, Christodoulou J, Ravine D, Ho G, Jacoby P, Anderson A, Pineda M, Ben-Zeev B, Bahi-Buisson N, Smeets E, Leonard H. Updating the profile of C-terminal MECP2 deletions in Rett syndrome. J Med Genet ;2009 (Nov 12)

Rett syndrome is a severe neurodevelopmental condition, currently diagnosed by application of recently revised clinical criteria.[1] Since the discovery in 1999 of the association between MECP2 mutations and Rett syndrome,[2] there has been considerable research into the relationship between genotype and phenotype in this disorder. This research has been able to link a number of the more common mutations to milder or more severe clinical features or to specific Rett syndrome variants.[3, 4, 5] In addition to the common point mutations (p.R106W, p.R133C, p.R168X, p.R255X, p.R270X, p.R294X, p.R306C and p.T158M) of MECP2 which are present in between 60% to 70% of cases with pathogenic MECP2 mutations,[3, 4, 6, 7] deletions in the C-terminal region have been reported in approximately 6-14% of cases.[3, 4, 7, 8] In one study the phenotype of ten cases with C-terminal deletions has been examined in detail,[9] but in no other study would they appear to have been specifically examined as a separate group. Using the data collected as part of InterRett, an international Rett syndrome phenotype database, and including data from the Australian Rett Syndrome Database, a population-based cohort, the phenotype of C-terminal deletions is described and compared with the phenotype of cases with all other mutations and also with recognised severe and mild mutations.

2. Belmonte MK, Gomot M, Baron-Cohen S. Visual attention in autism families : ’unaffected’ sibs share atypical frontal activation. J Child Psychol Psychiatry ;2009 (Nov 13)

Background : In addition to their more clinically evident abnormalities of social cognition, people with autism spectrum conditions (ASC) manifest perturbations of attention and sensory perception which may offer insights into the underlying neural abnormalities. Similar autistic traits in ASC relatives without a diagnosis suggest a continuity between clinically affected and unaffected family members. Methods : We applied fMRI in the context of a non-social task of visual attention in order to determine whether this continuity persists at the level of brain physiology. Results : Both boys with ASC and clinically unaffected brothers of people with ASC were impaired at a visual divided-attention task demanding conjunction of attributes from rapidly and simultaneously presented, spatially disjoint stimuli and suppression of spatially intervening distractors. In addition, both groups in comparison to controls manifested atypical fronto-cerebellar activation as a function of distractor congruence, and the degree of this frontal atypicality correlated with psychometric measures of autistic traits in ASC and sibs. Despite these resemblances between the ASC and sib groups, an exploratory, hypothesis-generating analysis of correlations across brain regions revealed a decrease in overall functional correlation only in the ASC group and not in the sibs. Conclusions : These results establish a neurophysiological correlate of familial susceptibility to ASC, and suggest that whilst abnormal time courses of frontal activation may reflect processes permissive of autistic brain development, abnormal patterns of functional correlation across a wider array of brain regions may relate more closely to autism’s determinants.

3. Chien WH, Wu YY, Gau SS, Huang YS, Soong WT, Chiu YN, Chen CH. Association study of the SLC25A12 gene and autism in Han Chinese in Taiwan. Prog Neuropsychopharmacol Biol Psychiatry ;2009 (Nov 10)

PURPOSE : Autism is a childhood-onset neurodevelopmental disorder with a strong genetic component in its etiology. Several studies reported that the solute carrier family 25 member A12 (SLC25A12) gene was associated with autism. This study aimed to replicate this finding in a Han Chinese sample from Taiwan using a population-based case-control approach. METHODS : We genotyped two single nucleotide polymorphisms (SNPs, rs2056202 and rs2292813) of the SLC25A12 gene that were previously reported to be associated with autism in 465 patients (402 males and 63 females) and 450 control subjects (227 males and 223 females) from Taiwan. Differences in the genotype, allele, and haplotype frequencies between two groups were compared. RESULTS : We found no differences in the allele, genotype, or haplotype frequencies of these two SNPs between patients and controls. CONCLUSIONS : Our data do not support that the SLC25A12 gene is associated with autism in our population. The discrepant results other studies may come from the clinical heterogeneity of patients recruited for studies, or the genetic heterogeneity of autism in different populations.

4. Denis C, Jacquart J, Pitchot W. [Autistic or attachment disorders ? An ill-defined border]. Rev Med Liege ;2009 (Oct) ;64(10):506-511.Troubles autistiques ou troubles de l’attachement ? Une frontiere floue et mal definie.

We report 3 cases of 3- to 5-year-old children with symptoms suggesting an autistic disorder (language delay or absence of language, communication withdrawal and developmental delay). We believe that these cases should be preferentially interpreted in terms of attachment disorder with autistic withdrawal rather than pure autistic disorder. Their prognosis is far better than pure autistic disorders. We discuss the differential diagnosis between autistic and attachment disorders.

5. Huemer SV, Mann V. A Comprehensive Profile of Decoding and Comprehension in Autism Spectrum Disorders. J Autism Dev Disord ;2009 (Nov 14)

The present study examined intake data from 384 participants with autism spectrum disorders (ASD) and a comparison group of 100 participants with dyslexia on nine standardized measures of decoding and comprehension. Although diagnostic groups were based on parental reports and could not be verified independently, we were able to observe significant distinctions between subject groups. Overall findings confirm previous results of a disassociation between decoding and comprehension in ASD. Using a larger sample than previous studies and a greater variety of measures, a pattern of relatively intact decoding skills paired with low comprehension was found in autism, PDD-NOS, and Asperger’s. In contrast, the dyslexic group showed the opposite pattern of stronger comprehension and weaker decoding.

6. Kopp S, Beckung E, Gillberg C. Developmental coordination disorder and other motor control problems in girls with autism spectrum disorder and/or attention-deficit/hyperactivity disorder. Res Dev Disabil ;2009 (Nov 10)

Examine the rate, predictors, and effect on daily life skills of developmental coordination disorder (DCD) and other motor control difficulties in school age girls with autism spectrum disorder (ASD) and/or attention-deficit/hyperactivity disorder (ADHD), in preschool age girls with ASD referred to a neuropsychiatric clinic, and in a community sample of school age girls. The girls (131 in total) were examined with standardised test of motor function and parent interviews and questionnaires. The school girls were compared with 57 age-and IQ-matched girls from the community. DCD was diagnosed in 25% of clinic school girls with ASD, in 32% of those with ADHD, and in 80% of the clinic preschool girls with ASD. Parents reported more motor problems in the school age clinic group. Agreement between a brief motor screening test and a full comprehensive motor examination was moderate to good in the clinic group. Young age, autistic symptomatology, and low performance IQ predicted more motor coordination problems. Motor coordination problems were related to lower ability in daily life skills even when the effect of PIQ was controlled for. A large minority of school girls with ASD and/or ADHD, and a majority of preschool girls with ASD meet full diagnostic criteria for DCD. Their motor problems contribute to reduced activity in daily life even when the effects of IQ have been partialled out.

7. Liao P, Soong TW. Ca(V)1.2 channelopathies : from arrhythmias to autism, bipolar disorder, and immunodeficiency. Pflugers Arch ;2009 (Nov 15)

Mutations of human Ca(V)1.2 channel gene were identified only recently. The gain-of-function mutations were found at two mutually exclusive exons in patients with Timothy syndrome (TS). These patients exhibit prolonged QT interval and lethal cardiac arrhythmias. In contrast, the loss-of-function mutations of Ca(V)1.2 channel in patients with Brugada syndrome produce short QT interval that could result in sudden cardiac death. TS patients also suffer from multi-organ dysfunction that includes neurological disorder such as autism and mental retardation reflecting the wide tissue distribution of Ca(V)1.2 channel. Mutations found on different mutually exclusive exons determine the severity of the disease. Unexpectedly, TS patients may develop recurrent infections and bronchitis that suggests a role of Ca(V)1.2 channel in the immune system. Furthermore, recent reports revealed a linkage of Ca(V)1.2 channel polymorphism with multiple central nervous system disorders including bipolar disorder, depression, and schizophrenia. Here, we will discuss how alternative splicing modulates Ca(V)1.2 channelopathy and the role of Ca(V)1.2 channel in both excitable and non-excitable tissues.

8. Matson JL, Mahan S, Hess JA, Fodstad JC. Effect of developmental quotient on symptoms of inattention and impulsivity among toddlers with Autism Spectrum Disorders. Res Dev Disabil ;2009 (Nov 13)

The effect of developmental quotient on symptoms of inattention and impulsivity was examined among 198 toddlers with Autism Spectrum Disorders. There were two levels of developmental quotient : (1) low (less than or equal to 70 ; n=80), and (2) typical (greater than 70 ; n=118). Symptoms of inattention and impulsivity were assessed using 14 items that comprise the BISCIUT-Part 2 inattention/impulsivity subscale. There was no significant effect of developmental quotient on these items representing inattention and impulsivity when severity of Autism Spectrum Disorder symptoms was controlled for. However, the covariate, severity of Autism Spectrum Disorder symptoms, was significantly related to 12 of the 14 items. Percent endorsement of impairment of symptoms relating to inattention and impulsivity for the low and typical developmental quotient groups is also listed. Implications of the results are also discussed.

9. Schoen SA, Miller LJ, Brett-Green BA, Nielsen DM. Physiological and behavioral differences in sensory processing : a comparison of children with autism spectrum disorder and sensory modulation disorder. Front Integr Neurosci ;2009 ;3:29.

A high incidence of sensory processing difficulties exists in children with Autism Spectrum Disorder (ASD) and children with Sensory Modulation Disorder (SMD). This is the first study to directly compare and contrast these clinical disorders. Sympathetic nervous system markers of arousal and reactivity were utilized in a laboratory paradigm that administered a series of sensory challenges across five sensory domains. The Short Sensory Profile, a standardized parent-report measure, provided a measure of sensory-related behaviors. Physiological arousal and sensory reactivity were lower in children with ASD whereas reactivity after each sensory stimulus was higher in SMD, particularly to the first stimulus in each sensory domain. Both clinical groups had significantly more sensory-related behaviors than typically developing children, with contrasting profiles. The ASD group had more taste/smell sensitivity and sensory under-responsivity while the SMD group had more atypical sensory seeking behavior. This study provides preliminary evidence distinguishing sympathetic nervous system functions and sensory-related behaviors in Autism Spectrum Disorder and Sensory Modulation Disorder. Differentiating the physiology and sensory symptoms in clinical groups is essential to the provision of appropriate interventions.

10. Specchio N, Balestri M, Striano P, Cilio MR, Nardello R, Patane S, Margiotta ML, D’Orsi G, Striano S, Russo S, Specchio LM, Cusmai R, Fusco L, Vigevano F. Efficacy of levetiracetam in the treatment of drug-resistant Rett syndrome. Epilepsy Res ;2009 (Nov 13)

Rett syndrome (RTT) is a progressive neurological disorder characterized by a wide spectrum of phenotypes. Epilepsy is reported to occur in 50-90% of patients with RTT ; some develop medically refractory epilepsy. The aim of this study is to investigate the efficacy of levetiracetam (LEV) in drug-resistant patients with RTT. This prospective, pragmatic, open-label study consisted of an 8-week baseline period and a 6-month evaluation period. Efficacy variable was the mean frequency of monthly seizures before, and after 3 and 6 months of treatment with LEV. Eight female patients, aged 7.5-19 years (M12.8+/-5) entered the study. Mean age at epilepsy onset was 25.8+/-14.1 months. All patients showed MeCP2 mutation. Patients had been treated with a mean of 3.4 AEDs (2-7) before LEV. The mean LEV dose was 44.84+/-18.02mg/kg/day. The mean monthly seizure frequency for all types of seizures during the baseline period was 21.3+/-8.1 (range 10-35) ; after 3 months it was 3.3+/-4.1 (range 0-9) and after 6 months of LEV treatment it was 1.5+/-2 (range 0-4), p<0.0001. The mean follow-up period was 20.2+/-13 months. Mild sleepiness occurred in two patients, one reported intermittent agitation. Levetiracetam appeared effective in our series of drug-resistant RTT patients. All reported a reduction in seizure frequency and consequently a better quality of life.

11. Tanweer T, Rathbone CJ, Souchay C. Autobiographical memory, Autonoetic Consciousness, and Identity in Asperger Syndrome. Neuropsychologia ;2009 (Nov 12)

Previous results from research on individuals with Asperger syndrome (AS) suggest a diminished ability for recalling episodic autobiographical memory (AM). The primary aim of this study was to explore autobiographical memory in individuals with Asperger syndrome and specifically to investigate whether memories in those with AS are characterised by fewer episodic ’remembered’ events (due to a deficit in autonoetic consciousness). A further aim was to examine whether such changes in AM might also be related to changes in identity, due to the close relationship between memory and the self and to the established differences in self-referential processes in AS. Eleven adults with AS and fifteen matched comparison participants were asked to recall autobiographical memories from three lifetime periods and for each memory to give either a Remember response (autonoetic consciousness) or a Know response (noetic consciousness). The pattern of results shows that AS participants recalled fewer memories and that these memories were more often rated as Known, compared to the comparison group. AS participants also showed differences in reported identity, generating fewer social identity statements and more abstract, trait-linked identities. The data support the view that differences in both memory and reported personal identity in AS are characterized by a lack of specificity.

12. Yechiam E, Arshavsky O, Shamay-Tsoory SG, Yaniv S, Aharon J. Adapted to explore : Reinforcement learning in Autistic Spectrum Conditions. Brain Cogn ;2009 (Nov 11)

Recent studies have recorded a tendency of individuals with Autism Spectrum Conditions (ASC) to continually change their choices in repeated choice tasks. In the current study we examine if this finding implies that ASC individuals have a cognitive style that facilitates exploration and discovery. Six decision tasks were administered to adolescents with ASC and matched controls. Significant differences in shifting between choice options appeared in the Iowa Gambling task (Bechara, Damasio, Damasio, & Anderson, 1994). A formal cognitive modeling analysis demonstrated that for about half of the ASC participants the adaptation process did not conform to the standard reinforcement learning model. These individuals were only coarsely affected by choice-outcomes, and were more influenced by the exploratory value of choices, being attracted to previously un-explored alternatives. An examination of the five simpler decision tasks where the advantageous option was easier to determine showed no evidence of this pattern, suggesting that the shifting choice pattern is not an uncontrollable tendency independent of task outcomes. These findings suggest that ASC individuals have a unique adaptive learning style, which may be beneficial is some learning environment but maladaptive in others, particularly in social contexts.


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