Individuals with coexisting seizure disorder may require treatment with anticonvulsants. Prognosis
A 2013 review stated that life expectancy for FXS was 12 years lower than the general population and that the causes of death were similar to those found for the general population. Research
Fragile X syndrome is the most "translated" human neurodevelopmental disorder under study. Hence, research into the etiology of FXS has given rise to many attempts at drug discovery. The increased understanding of the molecular mechanisms of disease in FXS has led to the development of therapies targeting the affected pathways. Evidence from mouse models shows that mGluR5 antagonists (blockers) can rescue dendritic spine abnormalities and seizures, as well as cognitive and behavioral problems, and may show promise in the treatment of FXS. Two new drugs, AFQ-056 (mavoglurant) and dipraglurant, as well as the repurposed drug fenobam are currently undergoing human trials for the treatment of FXS. There is also early evidence for the efficacy of arbaclofen, a GABAB agonist, in improving social withdrawal in individuals with FXS and ASD. In addition, there is evidence from mouse models that minocycline, an antibiotic used for the treatment of acne, rescues abnormalities of the dendrites. An open trial in humans has shown promising results, although there is currently no evidence from controlled trials to support its use.The first complete DNA sequence of the repeat expansion in someone with the full mutation was generated by scientists in 2012 using SMRT sequencing.
The FMR1 mRNA contains the transcribed CGG-repeat tract as part of the 5 untranslated region, which hybridizes to the complementary CGG-repeat portion of the FMR1 gene to form an RNA·DNA duplex.A subset of people with intellectual disability and symptoms resembling fragile X syndrome are found to have point mutations in FMR1. This subset lacked the CGG repeat expansion in FMR1 traditionally associated with fragile x syndrome. Inheritance
Fragile X syndrome has traditionally been considered an X-linked dominant condition with variable expressivity and possibly reduced penetrance. However, due to genetic anticipation and X-inactivation in females, the inheritance of Fragile X syndrome does not follow the usual pattern of X-linked dominant inheritance, and some scholars have suggested discontinuing labeling X-linked disorders as dominant or recessive. Females with full FMR1 mutations may have a milder phenotype than males due to variability in X-inactivation.Before the FMR1 gene was discovered, analysis of pedigrees showed the presence of male carriers who were asymptomatic, with their grandchildren affected by the condition at a higher rate than their siblings suggesting that genetic anticipation was occurring. This tendency for future generations to be affected at a higher frequency became known as the Sherman paradox after its description in 1985. Due to this, male children often have a greater degree of symptoms than their mothers.The explanation for this phenomenon is that male carriers pass on their premutation to all of their daughters, with the length of the FMR1 CGG repeat typically not increasing during meiosis, the cell division that is required to produce sperm.