A 3.2 Mb deletion on 18q12 in a patient with childhood autism and high-grade myopia.

Autism spectrum disorders (ASDs) are a heterogeneous group of disorders with unknown aetiology. Even though ASDs are suggested to be among the most heritable complex disorders, only a few reproducible mutations leading to susceptibility for ASD have been identified. In an attempt to identify ASD susceptibility genes through chromosome rearrangements, we investigated a female patient with childhood autism and high-grade myopia, and an apparently balanced de novo translocation, t(5;18)(q34;q12.2). Further analyses revealed a 3.2 Mb deletion encompassing 17 genes at the 18q break point and an additional deletion of 1.27 Mb containing two genes on chromosome 4q35. Q-PCR analysis of 14 of the 17 genes deleted on chromosome 18 showed that 11 of these genes were expressed in the brain, suggesting that haploinsufficiency of one or more genes may have contributed to the childhood autism phenotype of the patient. Identification of multiple genetic changes in this patient with childhood autism agrees with the most frequently suggested genetic model of ASDs as complex, polygenic disorders.

The glass state: characterizing energy landscape features.

We probed the topologies imposed on configuration hyperspace by the potential energy function-the shapes of the constant potential energy manifolds-for the glassy state of monatomic Lennard-Jones matter, by following trajectories of constant potential energy. A prominent characteristic of this model matter is well-defined regions of confinement (pockets) in configuration hyperspace. We found that there are constant potential energy hyperspace paths (tubes) between such pockets, applying even to paths linking glassy regions to crystalline regions of configuration hyperspace. Also, we found that glass and crystal pockets are interspersed. For monatomic Lennard-Jones matter at least, the transition from glass to crystal therefore does not have to involve the traversing of a potential energy barrier, as is usually assumed.

Mammalian and avian neuroanatomy and the question of consciousness in birds.

Some birds display behavior reminiscent of the sophisticated cognition and higher levels of consciousness usually associated with mammals, including the ability to fashion tools and to learn vocal sequences. It is thus important to ask what neuroanatomical attributes these taxonomic classes have in common and whether there are nevertheless significant differences. While the underlying brain structures of birds and mammals are remarkably similar in many respects, including high brain-body ratios and many aspects of brain circuitry, the architectural arrangements of neurons, particularly in the pallium, show marked dissimilarity. The neural substrate for complex cognitive functions that are associated with higher-level consciousness in mammals and birds alike may thus be based on patterns of circuitry rather than on local architectural constraints. In contrast, the corresponding circuits in reptiles are substantially less elaborated, with some components actually lacking, and in amphibian brains, the major thalamopallial circuits involving sensory relay nuclei are conspicuously absent. On the basis of these criteria, the potential for higher-level consciousness in these taxa appears to be lower than in birds and mammals.