CD8A and hypoparathyroidism: Furthermore, HLA associations support an adaptive immune contribution: HLA-A*26:01 (MHC class I) is strongly linked to idiopathic hypoparathyroidism, implicating CD8+ cytotoxic T-cells, while HLA-DRB1*01 and HLA-DRB1*09 alleles are enriched in affected patients [27].