Some problems in the genetics of X-linked mental retardation

Balance and Coordination Proficiency of Age-Matched Male and Female Children and Adolescents With Intellectual Disabilities

Male youth (8-18 years) with intellectual disability (ID) demonstrate motor proficiency below age-related competence capacities for typically developing youth. Whether below-criteria motor proficiency also exists for females with ID is not known. The purpose of this study was to determine if sex-specific differences exist in motor proficiency for youth with ID. The Bruininks-Oseretsky Test of Motor Proficiency was used to measure motor proficiency: six items for upper limb coordination, seven items for balance, and six items for bilateral coordination. One hundred and seventy-two (172) males and 85 females with ID but without Down syndrome were divided into five age groups for comparative purposes: 8-10, 11-12, 13-14, 15-16, and 17-21 years. Males scored sufficiently higher than females to suggest that sex data should not be combined to established Bruininks-Oseretsky Test of Motor Proficiency standards for upper limb coordination, balance, and bilateral coordination subtests.

Scope for more genetic testing in learning disability. Case report of an inherited duplication on the X-chromosome

There have been major advances in the past few years in our understanding of the X-linked learning disabilities. The most common of these is the fragile-X syndrome, but the number of other gene defects that are now recognised to be linked with learning disability is increasing year on year. We describe one family displaying a family displaying a rare X-linked abnormality. Repeat genetic testing was requested for a family member with mild learning disability when, following chromosomal analysis for her brother, it became known that he had a genetic defect. The genetic defect 46, Xdup(X) (p22.13 p22.31) was identified. To our knowledge this is the first time this precise configuration has been demonstrated. We conclude that genetic testing for individuals with learning disability is worthwhile, even when there may be only a low index of suspicion.

The epidemiology of mental retardation: challenges and opportunities in the new millennium

There are a number of problems and challenges in relating the science of epidemiology to mental retardation (MR). These relate to how MR is defined and classified and how these definitions may change over time. These as well as other differences in ascertainment sources and methods need to be considered when comparing MR prevalence over time and place. On the other hand, advances in technology also provide new and efficient methods of data collection both by data linkage and by use of web-based methods to study rare diseases. While prevalence studies have not been individually reviewed, we have examined the range of data including recent studies relating to how prevalence differs according to age, gender, social class and ethnicity. Some problems with available etiological classification systems have been identified. Recent etiological studies, most of which use different classification systems, have been reviewed and explanations have been postulated to account for differences in results. Individual risk factors for MR are considered whilst the option of considering a population as opposed to a high risk strategy to MR prevention is raised. This might well involve improving the social milieu surrounding the occurrence of individual risk factors. The impact of biotechnological advances such as antenatal and neonatal screening and assisted reproduction on MR are discussed. The issue of how inequalities in access to technology may impact on case identification and even have the potential to further widen inequalities is raised. The importance of extending the use of epidemiological tools to study the social, health and economic burden of MR is also emphasized. However, in order to apply to MR the "prevention-intervention-research" cycle, which surely underpins all epidemiology, it is vital to ensure that the methodological challenges we raise are adequately addressed.