PER2 and metabolic syndrome: In addition, circadian clock genes have been shown to link with the individual components of MetS, including an association of NPAS2 rs11541353 with hypertension [10], an association of PER2 #10870 with high fasting glucose [10], and an association of CRY1 haplotype (rs4964513 and rs12821586) with elevated blood pressure [8].