ApoE gene polymorphism was examined in 100 adults with Down syndrome with and without dementia (Alzheimer's disease) and 346 control subjects. Additionally, a meta analysis of studies (total N=480 subjects) was performed. Results indicated a similar incidence of the gene across groups but subjects with the allele tended to an earlier onset of…

Retrospective longitudinal data on 21 boys with the fragile X syndrome were analyzed. Results indicated that 13 of the boys showed a significant decline in intelligence quotient at retest, suggesting that while young boys with this syndrome may be only mildly retarded, adults are usually moderately to severely retarded. (Author/DB)

Adaptive behavior was measured over time in 70 children, ages 1 to 12 years, with fragile X syndrome. With a mean of 4.4 assessments per child, adaptive behavior skills increased steadily and gradually over time. Children with less autistic behavior and higher percentages of the fragile X mental retardation gene protein showed better performance…

This study examined the prevalence and severity of self-injurious behavior (SIB) in 29 children and adults with Smith-Magenis syndrome, a genetic disorder usually involving moderate mental retardation. Findings confirmed the near universal presence of SIB in this population. The overall prevalence of SIB increased with age. Number of types of SIB…

This study of 640 twins with reading disability and 436 controls (mean age 12) examined external validity of the distinction between specific reading retardation and reading backwardness, in 3 domains: genetic etiology, sex ratio and clinical correlates, and neuropsychological profiles. There was no evidence of differential genetic etiology of the…