Fragile X-associated tremor/ataxia syndrome

Historical note and nomenclature
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By Niranjan N Singh MD and Florian P Thomas MD PhD

Researchers first began to look for a connection between fragile X syndrome A and the neurologic symptoms in elderly men when mothers of affected children noted that their children’s grandfathers became forgetful, had frequent falls, and other neurologic problems. This resulted in the recognition of a syndrome originally referred to as “intention tremor, parkinsonism, and generalized brain atrophy in male carriers of a fragile X premutation” (Hagerman et al 2001).

In fragile X syndrome A, a cytosine-guanine-guanine (CGG) triplet repeat expansion in excess of 200 repeats leads to silencing of the FMR1 gene and its protein product, fragile X mental retardation protein, whereas fragile X-associated tremor/ataxia syndrome patients have a triplet repeat expansion of 55 to 200 CGG repeats.