Adult-Onset PLA2G6-Associated Parkinsonism With Claval Hypertrophy: A Rare Radiological–Genetic Association

A man in his 20s presented with rapidly progressive spastic parkinsonism, right-hand focal dystonia, memory impairment, and behavioural changes over eight months, resulting in complete dependence. Examination showed spasticity, rigidity, bradykinesia, ankle clonus, postural instability, slowed saccades, and cognitive deficits (Mini-Mental State Examination 25/30, Montreal Cognitive Assessment 20/30). Brain magnetic resonance imaging revealed mild cerebellar atrophy, claval hypertrophy, and minimal lentiform susceptibility blooming. Whole-exome sequencing identified a heterozygous pathogenic PLA2G6 variant (c.2222G>A; p.Arg741Gln). No family history was present. Symptomatic treatment with levodopa/carbidopa, trihexyphenidyl, and baclofen yielded partial initial benefit but limited sustained response over six months of follow-up. This case expands the adult-onset PLA2G6-associated neurodegeneration phenotype by combining aggressive progression, early cognitive involvement, and rare infantile-like neuroimaging features with minimal iron deposition.