Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) is a late-onset neurodegenerative disorder caused by trinucleotide (CGG) expansions of 55-200 repeats in the Fragile X Mental Retardation 1 (FMR1) gene. FXTAS is often underdiagnosed due to its overlap with other movement disorders such as Parkinson's disease, particularly in patients with no known family history of Fragile X-related conditions.

CASE REPORT

A 77-year-old man with a ten-year history of progressive gait impairment, balance issues, and recurrent falls presented with a subtle decline in memory over the past year. Despite multiple evaluations, a definitive diagnosis remained elusive. The patient’s family history revealed Fragile X premutation in two nieces, which was not initially considered relevant and was not reported by the patient. Neurological examination showed mild nystagmus, left-predominant bradykinesia, rigidity, titubation, and mild bilateral kinetic tremors. An MRI of the brain revealed generalized atrophy with chronic microvascular ischemic changes, and a DaT scan was abnormal. Genetic testing confirmed a full mutation (>200 repeats) with no methylation of the FMR1 gene, manifesting as a premutation and leading to a diagnosis of FXTAS.

This case underscores the importance of considering FXTAS in the differential diagnosis of late-onset neurodegenerative disorders presenting with tremor, ataxia, and parkinsonism, especially when there is a family history suggestive of Fragile X-related conditions. DaT scan may be abnormal in FXTAS, which can lead to initial misdiagnosis of Parkinson’s disease or Multiple System Atrophy. Early recognition and diagnosis are essential for appropriate management and counselling.