Regarding APC, we demonstrate three cases of normal parathyroid tissue (Normal PT1-3) as well as a case of secondary hyperparathyroidism with hyperplasia (case SHPT1) displaying virtually no CpG promoter methylation, suggesting that methylation of this locus might be conserved to true tumorous lesions of the parathyroids, such as adenomas and carcinomas. This evidence concerns the gene APC and secondary hyperparathyroidism.