NIPA1 and hereditary spastic paraplegia: In the previous genetic screening studies of HSP, there was no NIPA1 mutation identified in German (Beetz et al., 2008), Italian (D'Amore et al., 2018), Korean (Yang et al., 2021) or Japanese (Ishiura et al., 2014) patients, and only one case carrying NIPA1 mutation found in France (Klebe et al., 2007), Hungarian (Balicza et al., 2016) and Danish (Svenstrup et al., 2011) patients, respectively (Table 3).