The disulfide isomerase family (QR or PDI family) is a group of enzymes involved in protein folding and modification, ensuring correct protein structure by catalyzing the formation, breakage, and rearrangement of disulfide bonds in proteins. This family mainly includes members such as PDI (protein disulfide isomerase), ERp57, ERp72, and P5. These enzymes are primarily located in the endoplasmic reticulum and are widely present in various cells and tissues. They participate in various biological processes, including protein folding, secretion, cellular stress response, and immune response. The specific expression and mutations of the genes are associated with various diseases, including neurodegenerative diseases, inflammatory diseases, and cancer.