A Bayesian two‐armed bandit model

A two‐armed bandit model using a Bayesian approach is formulated and investigated in this paper with the goal of maximizing the value of a certain criterion of optimality. The bandit model illustrates the trade‐off between exploration and exploitation, where exploration means acquiring scientific acknowledge for better‐informed decisions at later stages (ie, maximizing long‐term benefit), and exploitation means applying the current knowledge for the best possible outcome at the current stage (ie, maximizing the immediate expected payoff). When one arm has known characteristics, stochastic dynamic programming is applied to characterize the optimal strategy and provide the foundation for its calculation. The results show that the celebrated Gittins index can be approximated by a monotonic sequence of break‐even values. When both arms are unknown, we derive a special case of optimality of the myopic strategy.     

Standardization of capillary electrophoresis for diagnosis of fragile X syndrome in the Brazilian public health system

Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability. The most common etiology of the syndrome is expansion and methylation of a CGG trinucleotide at chromosome region Xq27.3 involving FMR1 (fragile X mental retardation 1 gene). This disorder is commonly underdiagnosed in children and adolescents, given the high clinical variability. In Brazil, molecular diagnosis of FXS by CE does not exist in the public health system. The current standard for separation and identification of DNA fragment sizes is 50 cm CE, which is uncommon in public genotyping laboratories. This study describes the standardization of 36 cm CE for fragment analysis of samples from patients with intellectual disability suggestive of FXS. Genomic dsDNA was isolated from patients and amplified by PCR using the FMR1 AmplideX^® Kit. It was then possible to detect changes in repeat length of FMR1, such as full mutation and premutation. Thus, the proposed standardization proved to be effective for the diagnosis of FXS, permitting suitable genetic counseling for families. Inclusion of molecular testing such as this in the Brazilian public health service bridges the gap between available technologies and effective diagnosis, universalizing access to genetic testing in central Brazil.