PIGR and kidney disorder: PTC-specific changes were also observed for genes with prior links to PTC damage; for example, PIGR, encoding the polymeric immunoglobulin receptor, which has been shown to increase in PTCs in a variety of kidney diseases, including DKD54; and those with no known associations to PTC function, for example, BDH2, encoding the enzyme 3-hydroxybutarate dehydrogenase 2, involved in fatty acid beta oxidation and epithelial cell differentiation; and S100A1, a member of the S100 family of calcium binding proteins with an array of downstream molecular functions.