MPZ and demyelinating polyneuropathy: These efforts revealed one novel variant (c.126-1086T>A) in a heterozygous state within MPZ-MCS3 (which resides in the first intron of MPZ; see Fig. 1A) in one patient from our cohort with congenital non-progressive central nervous system hypomyelination affecting the supratentorial structures, but no signs of demyelinating peripheral neuropathy (BAB1733; Fig. 1B).