Fragile X syndrome is the most common form of inherited mental retardation. The disorder is mainly caused by the expansion of the trinucleotide sequence CGG located in the 5' UTR of the FMR1 gene on the X chromosome. The abnormal expansion of this triplet leads to hypermethylation and consequent silencing of the FMR1 gene. Thus, the absence of the encoded protein (FMRP) is the basis for the phenotype. FMRP is a selective RNA-binding protein that associates with polyribosomes and acts as a negative regulator of translation. FMRP appears to play an important role in synaptic plasticity by regulating the synthesis of proteins encoded by certain mRNAs localized in the dendrite. An advancing understanding of the pathophysiology of this disorder has led to promising strategies for pharmacologic interventions.

中文翻译：

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脆性x综合征的病理生理学。

脆性X综合征是遗传性智力低下的最常见形式。该疾病主要是由于位于X染色体上FMR1基因5'UTR的三核苷酸序列CGG的扩增引起的。该三联体的异常扩增导致FMR1基因的超甲基化和沉默。因此，不存在编码蛋白（FMRP）是表型的基础。FMRP是一种选择性的RNA结合蛋白，与多核糖体缔合，并充当翻译的负调节剂。FMRP通过调节由树突中某些mRNA编码的蛋白质的合成，似乎在突触可塑性中起重要作用。对这种疾病的病理生理学的深入了解导致了有希望的药物干预策略。