DNA ANALYSIS OF THE FRAGILE-X-SYNDROME IN AN AT RISK PEDIATRIC POPULATION IN CROATIA - SIMPLE CLINICAL PRESELECTION CRITERIA CAN CONSIDERABLY IMPROVE THE COST-EFFECTIVENESS OF FRAGILE-X SCREENING STUDIES

Advances in understanding the molecular basis of the fragile X syndrom e, the most common cause of inherited mental retardation, have elicite d new prospects for population-based studies identifying affected indi viduals and fragile X families, thus contributing in prevention of the disease. In comparison with numerous fragile X screening studies wher e unselected groups of individuals with mental retardation, developmen tal delay, learning disability or autistic-like behaviour had been obs erved, we performed fragile X analysis on clinically preselected indiv uduals, The group we studied consisted of 108 children with mental ret ardation of unknown cause or positive family history who had at least one physical and/or behavioural characteristic often observed among fr agile X individuals, A relative high frequency of the fragile X positi ve cases (13% overall, 17.3% in males) was detected, suggesting that s imple preselection criteria can considerably increase the proportion o f fragile X-positive cases, and therefore, improve the cost-effectiven ess of fragile X testing, Retrospective clinical analysis using a simp lified six-item fragile X checklist confirmed that scoring criteria ca n be used to additionally preselect individuals at risk, Our results a lso indicate that this syndrome is underdiagnosed in Croatia and that a further effort must be made to detect unrecognised cases.