A fragile site on the X chromosome has been implicated in developmental disabilities among both males and females. Data are presented on the characteristics and treatment of fragile X syndrome patients that can assist the school psychologist in program planning and appropriate referral. (Author/TE)

Clinical histories and physical findings are presented for 2 sisters with Rett syndrome. The older sister, age 25, was typically affected, whereas the younger sister, 22 years old, was affected with a seizure disorder showing an unusually early onset. The paper discusses hypotheses in genetic causation of Rett syndrome. (JDD)

Examines Gregor Mendel's family background, schooling, and the brotherhood of his monastery life for insights into how Mendel was stimulated to engage in plant hybridization, his precursors, and why he was successful in his endeavors. (RT)

Psychiatric evaluation of 14 males (ages 3-27 years) with the fragile X syndrome found pervasive hyperactivity, impulsivity, and attentional deficits, and a significant degree of anxiety. However, diagnostic criteria for persistent pervasive developmental disorder and autism were not met. (Author/DB)

Analyzed genetic and environmental contributions to intellectual change in 258 adopted and 93 biological children of 3-14 years. The effect of genes and family environment was significant at the time of the first measurement, but only genes made an additional contribution between the first and the second. (RJC)

Criticizes the application of the statistical procedures of the population-genetic approach within evolutionary biology to the study of psychological development. Argues that the application of the statistical methods of population genetics--primarily the analysis of variance--to the causes of psychological development is bound to result in a…

Argues that Gottlieb rejects population sampling and statistical analyses of distributions as he proposes that his experimental brand of mechanistic science is the only legitimate approach to developmental research. Maintains that Gottlieb exaggerates developmental uncertainty, based on his own research with extreme environmental manipulations.…

Argues that a truly developmental behavior genetics will have to go beyond the traditional quantitative approach of population genetics in order to produce developmental explanatory content about differences and similarities in developmental outcomes. (MDM)

Describes a laboratory method to allow students to complete electrophoresis and staining of DNA samples within 1 45-minute classroom period. (MKR)

Data from 148 identical and 111 fraternal twin pairs in which at least 1 member had a reading disability were statistically analyzed. Results suggest that genetic and shared-environment influences both contribute to the observed covariance between reading and mathematical deficits. (Author/DB)

Presents an activity to construct DNA and RNA models consisting of hundreds of nucleotide units. Provides students with insight into the composition and use of the DNA code. (JRH)

Describes a project that introduces students to the field of biotechnology and provides them with an understanding of the basic principles and techniques as well as an opportunity to participate in experimental methodology. Presents specific science projects that deal with polymorphism in the lipase gene and the genetic engineering of a lipase…

Correlations on subscales of Wechsler intelligence quotient tests and the Revised Beta Examination were obtained for biologically related and unrelated individuals in 181 adoptive families in the Texas Adoption Project. Generally higher correlations for biologically related individuals support the importance of genetic influence in intellectual…

This nontechnical review of the literature on Rett Syndrome, a developmental disability found only in females, examines the syndrome's history, diagnostic criteria, clinical stages, incidence, differential diagnosis, etiology, genetics, treatment approaches, and prognosis. (Author/DB)

Comparison of the mental status of 30 subjects with Down's Syndrome mosaicism and 30 matched subjects with trisomy 21 Down's Syndrome found that the mean intelligent quotient of the mosaic Down's Syndrome group was significantly higher and that this group showed better verbal abilities and more normal visual-perceptual skills. (Author/DB)