Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by an expanded cytosine-adenine-guanine (CAG) trinucleotide repeat in the huntingtin (HTT) gene, typically presenting with progressive motor, cognitive, and psychiatric symptoms between the ages of 30 and 50 years. This study presents the clinical features of a 48-year-old woman with a three-year history of progressive memory impairment, concentration difficulties, and weakness. Neurological examination revealed psychomotor slowing, mild cognitive impairment, right-sided apparent weakness due to impaired motor coordination, right-sided hypoesthesia, hyperreflexia, mild dysarthria, extrapyramidal gait disturbances, and occasional choreiform movements. Laboratory tests excluded infectious and metabolic causes, and brain magnetic resonance imaging (MRI) showed no acute lesions. Electroencephalography (EEG) revealed focal slow waves in the left posterior region without epileptiform discharges, and neuropsychological assessment indicated borderline dementia with depressive-anxiety symptoms. Genetic testing confirmed a pathogenic CAG repeat expansion in the HTT gene (47 repeats in the affected allele), establishing the diagnosis of HD according to European Molecular Quality Network (EMQN) guidelines. This case emphasizes the importance of integrating clinical evaluation, neuropsychological assessment, and genetic testing in patients with progressive cognitive and motor symptoms, particularly when there is a positive family history.