CASR and secondary hyperparathyroidism: However, no evidence has been found of loss of CASR alleles (Farnebo et al., 1997) or CASR gene methylation being responsible for the reduced CaSR levels in primary and secondary hyperparathyroidism (Hofman-Bang et al., 2012; Sulaiman et al., 2013; Varshney et al., 2013).