The presence of biallelic pathogenic FIG4 variants is the typical underlying genetic cause of the rare demyelinating sensorimotor peripheral neuropathy CMT4J [14] Similarly to the reported patients with FIG4-related parkinsonism, CMT4J patients are usually compound heterozygous for a missense and a loss-of-function FIG4 mutation, with I41T being the most commonly identified missense variant [12,15] Few CMT4J patients were also found to be heterozygous carriers of I41T (18/4000, 0.45%); however, the possibility of overlooked mutations (e.g., deletions) cannot be dismissed [7]. Here, FIG4 is linked to Parkinson disease.