O conhecimento de genética consolidado para o diagnóstico da Síndrome do X-frágil e o desafio da sua inclusão nas políticas públicas de saúde.

Abstract

Since DNA structure was described, several studies have been carried out in genetics that promoted a revolution in the practice of medicine. Human syndromes that were practically undiagnosed became easily diagnosed with molecular tools. However, most of the genetic diseases remain under diagnostic obscurity, increasing health concerns for affected people and public demand for preventive health care such as the case of Fragile-X Syndrome, the most common heritable form of mental retardation in humans. FXS is caused by an expansion of CGG repeat sequence in the promoter region of FMR1 gene, located in Xq27.3. Both men and women are affected by FXS and pre-mutation can expand to a full mutation in the next generation. Under full mutation status ( 200 repeats) the gene is silenced and FMRP protein is not produced causing mental retardation, speech delay, and behavior problems, the most frequent symptoms in FXS. Prevalence of FXS is estimated in 1:4000 and 1:8000 and of carriers in the general population as 1:813 and 1:259 for men and women, respectively. Because of FXS potential to affect subsequent generations it is crucial to properly diagnose the syndrome. Laboratory analysis of DNA from FXS, using PCR or Southern Blotting, allows reaching the diagnosis in 99% of cases carrying mutated genes. However, to date the Brazilian Public Health System does not recognize the molecular methods to reach complete diagnostic in FXS. Early diagnose would allow fore more appropriate and efficient therapy approaches, favoring satisfactory development of all affected people, minimizing their suffering and the burden on their families, increasing, on the other hand, their quality of life which should go beyond survival.