TAY-SACHS DISEASE; TSD HEXOSAMINIDASE A; HEXA; Affected; bilateral cherry-red spots; behavioral problems; progressive encephalopathy; deficient hexosaminidase A activity in blood; donor subject is homozygous for a 4 base pair insertion in exon 11 of the HEXA gene [1278_1279insTATC] resulting in a premature termination signal; induced pluripotent stem cell line derived from fibroblast.