Letter by Brewster Regarding Article, "CKM Glu83Gly Is Associated With Blunted Creatine Kinase Variation, but Not With Myalgia".

In a recent article, Siddiqui et al1 aimed to gain insight in the known negative association between constitutive plasma creatine kinase (CK) and a rare single-nucleotide polymorphism in the CK gene coding for the cytoplasmic M isoenzyme monomer, CKM Glu83Gly (rs11559024). The authors report that the polymorphism is associated with lower plasma CK variability and inducibility, but not with myalgia. It is concluded that the findings represent a novel mechanistic rationale for a subpopulation of individuals presenting with statin intolerance or myalgia without raised CK levels.1 Although the data are promising, the authors should have included cytoplasmic CK in the discussion. There is no …