A twin and family study of the association between immune system dysfunction and dyslexia using blood serum immunoassay and survey data

We conducted a study of the association between developmental reading disability (DRD) and immune disorders (ID) using both survey and immunoassay data in two separate samples of families. One sample was made up of twins and their parents and was ascertained through a population-based sampling scheme. The other sample was a set of extended pedigrees selected for apparent autosomal dominant transmission of DRD. We failed to find an association between DRD and ID in either sample, regardless of the method used to assess immune system function. Even though our twin sample provided evidence that both DRD and immune conditions were significantly heritable, there was no evidence for a genetic correlation between ID and DRD nor was there any clear indication that a special subgroup of individuals may be comorbid for these conditions because of genetic reasons. How these negative findings can be reconciled with the developmental hypothesis of Geschwind, Behan, Galaburda, and colleagues, and how they may relate to the gene locus influencing DRD that has been recently located in the HLA region of the short arm of chromosome 6 is discussed.     

Environmental and genetic influences on prereading skills in Australia, Scandinavia, and the United States.

Individual differences in measures of prereading skills and in questionnaire measures of 4-5-year-old twins' print environments in Australia, Scandinavia, and the United States were explored with a behavioral-genetic design. Modest phenotypic correlations were found between environmental measures and the twins' print knowledge, general verbal ability, and phoneme awareness. Lower print knowledge in Scandinavian twins was related to country differences in preschool print environment. Latent-trait behavioral-genetic analyses indicated very strong shared-environment influences on individual differences in Print Knowledge. Genetic influence was also significant. Several other prereading skills varied in their environmental and genetic influence, including a significant contrast between Phonological Awareness and Print Knowledge. Rapid Naming also revealed very strong genetic influence, as did Verbal Memory. Stronger shared-environment influences were found for Vocabulary and Grammar/Morphology. Genetic and environmental correlations among latent traits for General Verbal Ability, Phonological Awareness, and Print Knowledge were high, but there were also significant independent genetic and environmental contributions to each skill. Practical implications include the need for substantial and sustained instructional support for children hampered by genetic constraints on early literacy development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in executive functions are almost entirely genetic in origin.

Recent psychological and neuropsychological research suggests that executive functions--the cognitive control processes that regulate thought and action--are multifaceted and that different types of executive functions are correlated but separable. The present multivariate twin study of 3 executive functions (inhibiting dominant responses, updating working memory representations, and shifting between task sets), measured as latent variables, examined why people vary in these executive control abilities and why these abilities are correlated but separable from a behavioral genetic perspective. Results indicated that executive functions are correlated because they are influenced by a highly heritable (99%) common factor that goes beyond general intelligence or perceptual speed, and they are separable because of additional genetic influences unique to particular executive functions. This combination of general and specific genetic influences places executive functions among the most heritable psychological traits. These results highlight the potential of genetic approaches for uncovering the biological underpinnings of executive functions and suggest a need for examining multiple types of executive functions to distinguish different levels of genetic influences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic and environmental components of "environmental" influences.

Proposes a model of the effects of genotype-environment correlation in nonadoptive families and adoptive families that formalizes the possibility that the correlation between measures of the environment and of child development may be mediated genetically as well as environmentally. The model assumes that adoptive and nonadoptive homes are comparable in terms of means and variances of the environmental measures and that selective placement, the matching of birth parents and adoptive parents on the trait in question, is negligible. Data from classical adoption studies and new data on 185 adoptees (aged 12–24 mo) and 162 nonadoptive families from the Colorado Adoption Project (CAP) are used to illustrate the model and to provide quantitative estimates of the genetic and environmental components of environment-behavior correlations. Instruments used in the CAP study included the Home Observation for Measurement of the Environment, the Family Environment Scale, and the Childhood Temperament Inventory. 113 environment-infant correlations in nonadoptive families and 113 correlations in adoptive families constitute the basic data that were used to assess the extent to which the environment-development correlations in nonadoptive families exceed those in adoptive families. The results from the CAP suggest that correlations between widely used environmental measures and major domains of infant development are mediated genetically to a substantial extent—approximately 50% on the average. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mapping canopy damage from understory fires in Amazon forests using annual time series of Landsat and MODIS data

Understory fires in Amazon forests alter forest structure, species composition, and the likelihood of future disturbance. The annual extent of fire-damaged forest in Amazonia remains uncertain due to difficulties in separating burning from other types of forest damage in satellite data. We developed a new approach, the Burn Damage and Recovery (BDR) algorithm, to identify fire-related canopy damages using spatial and spectral information from multi-year time series of satellite data. The BDR approach identifies understory fires in intact and logged Amazon forests based on the reduction and recovery of live canopy cover in the years following fire damages and the size and shape of individual understory burn scars. The BDR algorithm was applied to time series of Landsat (1997-2004) and MODIS (2000-2005) data covering one Landsat scene (path/row 226/068) in southern Amazonia and the results were compared to field observations, image-derived burn scars, and independent data on selective logging and deforestation. Landsat resolution was essential for detection of burn scars < 50 ha, yet these small burns contributed only 12% of all burned forest detected during 1997-2002. MODIS data were suitable for mapping medium (50-500 ha) and large (> 500 ha) burn scars that accounted for the majority of all fire-damaged forests in this study. Therefore, moderate resolution satellite data may be suitable to provide estimates of the extent of fire-damaged Amazon forest at a regional scale. In the study region, Landsat-based understory fire damages in 1999 (1508 km²) were an order of magnitude higher than during the 1997-1998 El Niño event (124 km² and 39 km², respectively), suggesting a different link between climate and understory fires than previously reported for other Amazon regions. The results in this study illustrate the potential to address critical questions concerning climate and fire risk in Amazon forests by applying the BDR algorithm over larger areas and longer image time series.     

Familial patterns of impairment in reading disability.

Used psychometric evaluation (e.g., the Illinois Test of Psycholinguistic Ability, the Peabody Individual Achievement Tests, and the Goldman-Fristoe-Woodcock Test of Auditory Discrimination) of 58 reading-disabled children (probands), matched controls, and their nuclear families to identify familial patterns of impairment of cognitive abilities. Probands and their male relatives manifested deficits in reading, spelling, auditory memory, perceptual speed, and verbal reasoning. Mothers and sisters of probands appeared to be less severely affected, although only one test, the Peabody, revealed a significant interaction between sex and family type (experimental vs control). Hypotheses that the condition is due to a single gene with reduced penetrance in females or to a polygenic system in which the threshold for expression is higher in females cannot be rejected. On the other hand, it is also possible that reading disability may be a heterogeneous disorder produced by several different combinations of hereditary and environmental factors. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adoption results for self-reported personality: evidence for nonadditive genetic effects?

Fas antigen is constitutively expressed in the normal colon epithelium, but considerably diminished in most colorectal carcinomas. In the present study, we examine the relationship between Fas antigen expression and apoptosis using the colorectal carcinoma cell line COLO 201, on which a low grade of Fas antigen is expressed. Anti-Fas antibody had no effect on the induction of apoptosis of COLO 201. However, TNF-alpha and/or IFN-gamma, independently and additively, up-regulated Fas antigen expression on COLO 201 and induced apoptosis in a dose-dependent manner. Both cytokines also increased the COLO 201 sensitivity to anti-Fas antibody, resulting from the down-modulation of Bcl-2 and the up-regulation of Bax. These findings indicate that cytokine(s) plus anti-Fas antibody (which mimics natural Fas ligand) are more effective in inducing apoptosis of COLO 201 than cytokine(s) alone. These findings suggest that immunotherapy in combination with cytokine(s) and lymphokine-activated killer (LAK) cells will become a more effective therapy for cancer than cytokine(s) or LAK cells alone, since the Fas ligand is expressed on activated T cells, natural killer cells and macrophages.     

Genetic influence on tester-rated infant temperament as assessed by Bayley's Infant Behavior Record: Nonadoptive and adoptive siblings and twins.

Reports results for the 1st sibling adoption study of temperament in infancy, using tester ratings on the Infant Behavior Record (IBR) at 1 and 2 yrs of age for a sample of 95 pairs of nonadoptive siblings and 80 pairs of adoptive siblings. Twin data reported by A. P. Matheny (1980) for 85 identical and 50 fraternal twin pairs on the same measure at the same ages were combined with the sibling adoption data in maximum-likelihood model-fitting analyses for 3 IBR factors (affect-extraversion, activity, and task orientation). Both the sibling adoption and twin data yielded evidence for significant genetic influence for the 3 IBR factors at 12 and 24 mo: Heritability estimates ranged from 35–57%. Shared environment contributed little to the total variance for any of the 3 traits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced algorithm performance for land cover classification fromremotely sensed data using bagging and boosting

Two ensemble methods, bagging and boosting, were investigated for improving algorithm performance. The authors' results confirmed the theoretical explanation of L. Breiman (1996) that bagging improves unstable, but not stable, learning algorithms. While boosting enhanced accuracy of a weak learner, its behavior is subject to the characteristics of each learning algorithm     

Genetic and Environmental Contributions to General Cognitive Ability Through the First 16 Years of Life.

The genetic and environmental contributions to the development of general cognitive ability throughout the first 16 years of life were examined using sibling data from the Colorado Adoption Project. Correlations were analyzed along with structural equation models to characterize the genetic and environmental influences on longitudinal stability and instability. Intraclass correlations reflected both considerable genetic influence at each age and modest shared environmental influence within and across ages. Modeling results suggested that genetic factors mediated phenotypic stability throughout this entire period, whereas most age-to-age instability appeared to be due to nonshared environmental influences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)