Box 1.

Focusing a literature search

Baseline risk In a 7-year-old boy (population) with mental retardation who does not have a diagnosis responsive to specific interventions (exposure), what is the risk of having the fragile X chromosome (outcome)? Search: MEDLINE 1966 to present and EMBASE (Winspirs); search terms fragile X (text or MeSH heading) AND prevalence Baseline risk In a boy with mental retardation (population) and no dysmorphic features (negative test result), what is the risk of having the fragile X chromosome (outcome)? Baseline risk In a boy with mental retardation (population) with dysmorphic features (positive test result), what is the risk of having the fragile X chromosome (outcome)? Search: MEDLINE (PubMed Clinical Queries); search term fragile X—click on “diagnosis” and “specificity” Intervention/therapy In a boy with mental retardation (population), does knowing the diagnosis of fragile X chromosome (exposure) improve the parents' ability to plan and cope (outcome)? Search: MEDLINE (PubMed); search terms parents AND fragile X/diagnosis