Tay Sachs disease variant B1 (TSD B1; OMIM 272800) is a neurodegenerative lysosomal storage disease (LSD) which, although rare, is the most frequent form of TSD in Portugal. The mutation p.R178H (c.533G>A; rs28941770), associated with TSD B1, leads to a mutant HexA protein with altered kinetics and reduced residual activity. The availability of disease-relevant cell types derived from induced pluripotent stem c...