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Fragile X syndrome is the world's most common hereditary cause of intellectual disability in men and to a lesser extent in women. The disorder is caused by the silencing of a single gene on the X chromosome, the Fragile X Mental Retardation Gene-1. A substantial body of research across the disciplines of molecular genetics, child psychiatry and developmental neuroscience bears testament to a decade of exciting and innovative science that has advanced our knowledge about the fragile X "signature" or influence across cognitive and social development. The core aims of this review are to first discuss fragile X syndrome and premutation involvement in the context of current advances that demonstrate the dynamic nature of the genotype on phenotypic outcomes. Second, to discuss the implications of these recent advances for the development of clinical and educational interventions and resource tools that target specific phenotypic "signatures" within the fragile X continuum.

This is the first published case description in the current literature of the association of definite Gilles de la Tourette syndrome (GTS) and the Smith-Magenis syndrome (SMS), both confirmed by DSM-IV-TR criteria and molecular cytogenetic analysis, respectively. The co-occurrence of GTS, SMS and their common behavioural/neuropsychiatric abnormalities should warrant further genetic investigation of chromosome 17p11.2 deletion site as it may be a promising region for containing a gene(s) of aetiological importance in the development of the GTS phenotype. Alternatively, the co-occurrence may be due to the common endophenotypic mechanisms shared by these disorders, rather than being specific for GTS that could be explored using strategies of quantitative trait loci--endophenotype-based approach. Research into this genomic region may also benefit psychiatric genetic research in enhancing understanding of the biological and molecular underpinnings of common behavioural problems that are seen in both GTS and SMS. This would lead to advancement in neurobehavioural/neuropsychiatric genetics which will help in further explaining the broader perspective of gene-brain-behaviour interrelationships.

Background: Post-traumatic stress disorder (PTSD) is common and treatable. There is extensive research on people of average intelligence yet little on individuals with developmental disabilities. Methods: We report two people with intellectual disability (ID) who experienced PTSD. The relevance of their developmental difficulties, social and communication profiles, attentional skills, and causes of these, to their presentations is discussed. Results: Both individuals have fragile X syndrome and severe ID. One has Diagnostic and Statistical Manual - 4th Edition (DSM-IV) autistic disorder; the other DSM-IV attention deficit-hyperactivity disorder. They experienced developmental and psychological regressions, new challenging behaviours and exacerbations of existing ones coincident with emotional trauma. PTSD symptoms and phenomena were identifiable despite intellectual and communicatory impairments. Conclusion: Presentation of PTSD is influenced by degree and cause of ID, social circumstances, social and communicatory skills, nature and timing of traumatic experience and subsequent management. The paucity of literature suggests it is missed frequently in individuals with ID who risk having problems misattributed to other causes with potential for inappropriate interventions.

Abstract Two independent and complementary studies were conducted to assess the ability of boys with fragile-X syndrome to recognize facial and emotional expressions. Both studies failed to find any specific deficits associated with fragile-X syndrome. The performance of the test group was comparable to the level of subjects with intellectual disability and subjects of average cognitive development matched for intellectual ability. This suggests that chronological age and intellectual level are unlikely to explain the findings. The results are discussed in the context of the controversy surrounding the relationship between autism and fragile-X syndrome. The findings are consistent with fragile-X individuals having a profile of social, communicatory and ritualistic disturbances, which in some ways may differ from those found in individuals who have more typical autistic spectrum disorders. [ABSTRACT FROM AUTHOR]