A 39-year-old male from Western India presented with insidious onset, gradually progressive symptoms in the form of generalized seizures, followed by extrapyramidal symptoms and cognitive decline. Symptoms started with bradykinesia and anhedonia, and the patient was diagnosed with depression and treated with antidepressants for the initial few years. Over the next 4-5 years, he developed progressive dysarthria, an inability to do activities of daily living, and myoclonus. On examination, he was found to have frontal predominant cognitive dysfunction, dysarthria with logorrhea and paraphasia, and extrapyramidal features in the form of bilateral cogwheel rigidity, bradykinesia and dystonia. Basic metabolic panel, EEG, and CSF studies were found to be within normal limits, and MRI Brain demonstrated diffuse cerebral atrophy. In view of multi-neuraxial involvement with adult-onset seizures and myoclonus, other diagnoses like autoimmune encephalitis, SSPE, and storage disorders were considered. After ruling out the former two diagnoses, whole exome sequencing was done, which showed a mutation in the CTSF gene, thus confirming Type B Kuf's disease. Patient was treated with antiepileptics and antipsychotics with some symptomatic improvement.

This case draws attention to the challenges in diagnosing adult-onset genetic metabolic disorders. It should be considered in young adults presenting with unexplained progressive neurodegeneration and negative evaluation, and genetic testing may prove to be the cornerstone in the diagnosis and further prognostication in such diseases.