1. Cohen IL, Liu X, Lewis ME, Chudley A, Forster-Gibson C, Gonzalez M, Jenkins E, Brown WT, Holden JJ. {{Autism severity is associated with child and maternal MAOA genotypes}}. {Clin Genet} (May 22)
Cohen IL, Liu X, Lewis MES, Chudley A, Forster-Gibson C, Gonzalez M, Jenkins EC, Brown WT, Holden JJA. Autism severity is associated with child and maternal MAOA genotypes. We replicated and extended a previously reported association between autism severity and a functional polymorphism in the monoamine oxidase A (MAOA) promoter region, MAOA-uVNTR, in a sample of 119 males, aged 2-13 years, with autism spectrum disorder from simplex families. We demonstrated that (i) boys with the low activity 3-repeat MAOA allele had more severe sensory behaviors, arousal regulation problems, and aggression, and worse social communication skills than males with the high activity allele; and (ii) problems with aggression, as well as with fears and rituals, were modified by the mothers’ genotype. Boys with the 4-repeat high activity allele who had homozygous 4-repeat mothers showed increased severity of these behaviors relative to those born to heterozygous mothers. These findings indicate the importance of considering maternal genotype in examining associations of MAOA and other genes with behavior in male offspring.
2. Freilinger M, Bebbington A, Lanator I, de Klerk N, Dunkler D, Seidl R, Leonard H, Ronen GM. {{Survival with Rett syndrome: comparing Rett’s original sample with data from the Australian Rett Syndrome Database}}. {Dev Med Child Neurol} (Jun 22)
Aim Rett syndrome is a severe neurodevelopmental disorder that typically affects females. Little is known about the natural history and survival time of these females. Method We compared the survival of all Austrian female participants from Rett’s historical cohort (1966) with that of affected females registered in the Australian Rett Syndrome Database. The analysis included both Kaplan-Meier analysis and a log-rank test for equality of survivor functions. Results Of females in the original Austrian group, three are still alive. The median age at death was 13 years 4.8 months. The probability of survival up to the age of 25 years was 21%, compared with 71% in the Australian cohort (p<0.001). We found no practical or statistically significant differences in survival between the various birth year groups within the Australian cohort. Interpretation Our data indicate that survival of females with Rett syndrome has improved since the late 1960s but that there has been shown no change in survival over the last 30 years, possibly because the follow-up time has been too short.
3. Mitchell P, Mottron L, Soulieres I, Ropar D. {{Susceptibility to the Shepard illusion in participants with autism: reduced top-down influences within perception?}}. {Autism Res} (May 26);3(3):113-119.
Previous research [Ropar & Mitchell, 2002] has shown that autistic individuals are somewhat immune to biases induced by top-down processes, particularly the influence of previous knowledge on perception. In order to test this hypothesis within perception, 18 participants with autism who had measured intelligence in the normal range were compared against 18 matched controls in their susceptibility to the Shepard illusion. The illusion consists in misperceiving the shape of a parallelogram in the presence of depth cues. It is attributed [Mitchell, Ropar, Ackroyd, & Rajendran, 2005] to the effect of top-down constraints within perception. The task involved adjusting a stimulus to the dimensions of a template on a computer screen. Both groups were susceptible to the illusion and the illusion effect was stronger when three-dimensional perspective cues were prominent. Notably, participants with autism were less susceptible to the illusion than typically developing individuals. The findings raise the possibility that in some instances top-down influences are attenuated in individuals with autism.
4. Puzzo I, Cooper NR, Vetter P, Russo R. {{EEG activation differences in the pre-motor cortex and supplementary motor area between normal individuals with high and low traits of autism}}. {Brain Res} (Jun 25);1342:104-110.
The human mirror neuron system (hMNS) is believed to provide a basic mechanism for social cognition. Event-related desynchronization (ERD) in alpha (8-12Hz) and low beta band (12-20Hz) over sensori-motor cortex has been suggested to index mirror neurons’ activity. We tested whether autistic traits revealed by high and low scores on the Autistic Quotient (AQ) in the normal population are linked to variations in the electroencephalogram (EEG) over motor, pre-motor cortex and supplementary motor area (SMA) during action observation. Results revealed that in the low AQ group, the pre-motor cortex and SMA were more active during hand action than static hand observation whereas in the high AQ group the same areas were active both during static and hand action observation. In fact participants with high traits of autism showed greater low beta ERD while observing the static hand than those with low traits and this low beta ERD was not significantly different when they watched hand actions. Over primary motor cortex, the classical alpha and low beta ERD during hand actions relative to static hand observation was found across all participants. These findings suggest that the observation-execution matching system works differently according to the degree of autism traits in the normal population and that this is differentiated in terms of the EEG according to scalp site and bandwidth.
