Revista portuguesa de cardiologia : orgão oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology
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Hypertrophic cardiomyopathy (HCM) is the most common genetic heart disease and is often a consequence of mutations in the myosin-binding protein C gene (MYBPC3). Until now, however, no systematic review has been published on mutations of this gene in a Portuguese population. ⋯ In a Portuguese population of 45 HCM patients, 5 (11.1%) had mutations in the MYBPC3 gene (3 missense mutations--theoretically less frequent in the MYBPC3 gene--and 2 deletions). Four of these were 'new' mutations and 3 of them were located in exon 17 (which may be a 'hot spot' for MYBPC3 gene mutations in the Portuguese population). In all the patients, the phenotypic expression was different from that usually described for these mutations; in 3 of our patients, the clinical manifestations and penetrance were of early onset and one patient had a highly symptomatic form of obstructive hypertrophic cardiomyopathy. These data reflect the large number of exceptions to the classic genotype-phenotype correlations in HCM, highlighting the role of other factors, genetic and non-genetic, in regulating penetrance, clinical expression and prognosis in each family and in each individual patient.
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Clinical practice should be based on the best available information from high-quality studies. Among the various study models, the randomized controlled trial, despite some disadvantages, is usually considered the gold standard for determining the efficacy of an intervention (drugs, surgery, etc.), and so this type of study should be part of all rational, conscious clinical decision-making. In this article, we present the classic structure of a randomized controlled trial, together with indications for critical appraisal of quality, as well as a brief discussion of the design, conduct and results, for correct determination of an intervention's effect.