DDIT3 and deafness: It was noted that mutations in BAP31 caused a severe X-linked phenotype with deafness, dystonia and disorganization in the Golgi apparatus, but failed to show any increase of UPR markers of DNA damage inducible transcript 3 (DDIT3), heat shock protein family A (Hsp70) member 5 (HSPA5, also known as GRP78) and XBP1 when the cells were treated with the ER stress inducer of Thapsigargin.