Table 4. Summary of clinical and radiological features of PLAN phenotypes[22].

	INAD	Atypical NAD	PLAN-DP
Age of onset	6 months to 3 years	Early childhood; can be as late as end of second decade	4–36 years
Brain MRI	Cerebellar atrophy, cerebellar gliosis, posterior corpus callosum abnormalities (thinning, vertical orientation, elongation), apparent claval hypertrophy, iron deposition in basal ganglia (increases with age)	Iron deposition with or without cerebellar atrophy	Normal imaging, cerebral and/or cerebellar atrophy, iron deposition in basal ganglia (33%), corpus callosum changes similar to INAD (some cases)
Disease presentation	Gait disturbance and loss of ambulation, truncal hypotonia with hyper-reflexia and hypertonicity, neuroregression with loss of acquired motor skills	Gait impairment or ataxia; social communication difficulties, such as speech difficulties and autistic trait	Gait impairment, dystonia, Parkinsonism, tremor at rest, speech difficulties, and neuropsychiatric disorders
Disease progression	Spastic tetraparesis, with symmetrical pyramidal tract signs and areflexia	Dystonia and dysarthria, neuropsychiatric features, such as hyperactivity, impulsivity, emotional lability, and poor attention	Severe dystonia and/or Parkinsonism, spasticity, myoclonus, autonomic dysfunction, seizure, neuropsychiatric features, and cognitive decline
Ocular abnormalities	Strabismus, nystagmus, optic nerve atrophy	Strabismus, nystagmus, optic nerve atrophy	Supranuclear gaze palsy, slow saccades, fragmented saccades, nystagmus, lid opening apraxia

INAD, Infantile Neuroaxonal Dystrophy; MRI, Magnetic Resonance Imaging; PLAN-DP, PLA2G6-associated Neurodegeneration Dystonia–Parkinsonism.