Using multiple-tact training to produce emergent visual categorization in children with autism.

Previous research has shown that children with autism spectrum disorder (ASD) can categorize visual stimuli without direct training when they can also tact these stimuli using a common name and behave as listeners in relation to this name. However, children usually learn to assign objects specific names prior to learning the category to which they belong. The current study replicated previous research and evaluated whether multiple-tact training would establish visual categorization (measured by a picture sorting test) and listener behavior. We used a nonconcurrent multiple baseline design across 2 children with autism spectrum disorder. After multiple-tact training, we assessed whether participants would visually categorize stimuli based on their common category name. Both participants categorized and engaged in the corresponding listener behavior.

Rare α0-thalassemia deletions detected by MLPA in five unrelated Brazilian patients

Abstract Alpha-thalassemias are among the most common genetic diseases in the world. They are characterized by hypochromic and microcytic anemia and great clinical variability, ranging from a practically asymptomatic phenotype to severe anemia, which can lead to intrauterine or early neonatal death. Deletions affecting the α-globin genes, located on chromosome 16p13.3, are the main causes of α-thalassemia. Multiplex ligation-dependent probe amplification (MLPA) can be used to detect rearrangements that cause α-thalassemia, particularly large deletions involving the whole α cluster and/or deletions in the HS-40 region. Here, MLPA was used to investigate the molecular basis of α-thalassemia in five unrelated patients, three of whom had Hb H disease. In addition to the -α3.7 deletion identified in the patients with Hb H disease, four different α0 deletions removing 15 to 225 kb DNA segments were found: two of them remove both the α genes, one affects only the regulatory element (HS-40) region, and another one extends over the entire α cluster and the HS-40 region. These results illustrate the diversity of α-thalassemia deletions in the Brazilian population and highlight the importance of molecular investigation in cases that present with microcytosis and hypochromia without iron deficiency and normal or reduced Hb A2 levels..

Rare α0-thalassemia deletions detected by MLPA in five unrelated Brazilian patients.

Alpha-thalassemias are among the most common genetic diseases in the world. They are characterized by hypochromic and microcytic anemia and great clinical variability, ranging from a practically asymptomatic phenotype to severe anemia, which can lead to intrauterine or early neonatal death. Deletions affecting the α-globin genes, located on chromosome 16p13.3, are the main causes of α-thalassemia. Multiplex ligation-dependent probe amplification (MLPA) can be used to detect rearrangements that cause α-thalassemia, particularly large deletions involving the whole α cluster and/or deletions in the HS-40 region. Here, MLPA was used to investigate the molecular basis of α-thalassemia in five unrelated patients, three of whom had Hb H disease. In addition to the -α3.7 deletion identified in the patients with Hb H disease, four different α0 deletions removing 15 to 225 kb DNA segments were found: two of them remove both the α genes, one affects only the regulatory element (HS-40) region, and another one extends over the entire α cluster and the HS-40 region. These results illustrate the diversity of α-thalassemia deletions in the Brazilian population and highlight the importance of molecular investigation in cases that present with microcytosis and hypochromia without iron deficiency and normal or reduced Hb A2 levels..

The effects of listener training on discriminative control by elements of compound stimuli in children with disabilities.

The purpose of the current study was to assess whether the establishment of listener relations with compound stimuli as samples and comparisons would lead to the emergence of: (1) speaker behavior in the form of tacts of the compound stimuli; (2) listener and tact responses for untaught compounds; and (3) listener and tact responses for the isolated properties of compounds. Participants were four boys diagnosed with autism and one diagnosed with intellectual disability. We taught participants to select among three compound comparisons consisting of combinations of shapes and patterns in the presence of the corresponding dictated word. Subsequently, we tested for the emergence of tacts for the trained compounds, as well as tact and listener relations for six untaught compounds and their properties. In general, results showed that the acquisition of listener relations led to the emergence of the corresponding tacts, as well as the emergence of listener and tact responses for untaught combinations for three out of five participants. By contrast, the other two participants showed responding characteristic of restricted stimulus control. These results suggest that the establishment of bidirectional relations between listener and speaker behaviors may facilitate the emergence of control by properties of compound stimuli.

The effects of listener training on the emergence of tact and mand signs by individuals with intellectual disabilities.

The purpose of the current study was to assess whether individuals with intellectual disabilities would emit untrained speaker responses (i.e., signed tacts and mands) after being taught listener behaviors. Listener relations were trained via an automated matching-to-sample (MTS) procedure. Following mastery, the emergence of signed tacts, generalized tacts, and mands was tested. All participants met criterion in listener relations training and showed the emergence of almost all relations. Results suggest that teaching listener relations first, through MTS tasks, is a viable way to produce emergence of speaker relations.

Haplotypes of alpha-globin gene regulatory element in two Brazilian native populations.

The alpha-major regulatory element (alpha-MRE), located 40 Kb far upstream of the alpha-globin gene cluster on chromosome 16, is involved in the regulation of human alpha-globin genes expression. The activity of this element is restricted to a 350-bp fragment in which several nuclear protein binding sites have been identified. This element is genetically polymorphic and different haplotypes, named A-F, have been determined in seven populations of Europe, Africa, Asia, and Oceania. We describe here the alpha-MRE haplotypes found in native Indians from two nonmiscegenated tribes of the north region of Brazil, in Amazonia, the Parakanã and the Xikrin. The A haplotype was predominant in both (70% and 87%, respectively), followed by the B haplotype (30% and 13%, respectively). The haplotype frequency distribution among the Parakanã was similar to that reported for Indonesians and Southeast Asian populations, while the distribution among the Xikrin showed higher similarity to that observed in Indonesians. These results corroborate the existence of genetic affinities between Brazilian Indians and Southeast Asian and Oceanic populations. This was the first investigative work on the alpha-MRE polymorphism in South American native populations in general or Brazilian native populations in particular.