CYP27A1 and metachromatic leukodystrophy: This seems likely, since (i) MRI studies have demonstrated loss of white matter integrity in sporadic bvFTD [72, 73] and (ii) rare variants in genes whose loss of function is associated with the severe inherited leukodystrophies hypomyelinating leukodystrophy (TMEM106B gene), Nasu-Hakola disease (TREM2), metachromatic leukodystrophy (ARSA), and cerebrotendinous xanthomatosis (CYP27A1), are also known to cause FTD with TDP-43 deposition [74].