Common Creatine Kinase gene mutation results in falsely reassuring CK levels in muscle disorders

Creatine Kinase (CK) is the enzyme responsible for catalysing the exchange of phosphates in the creatine/phosphocreatine shuttle. Skeletal muscle CK is made up of 90% muscle CK (CKMM) and 10% heart CK (CK-MB). In muscle damage (e.g. rhabdomyolysis), extreme exercise and statin-induced myositis, serum CK can be raised in excess of 10 times the upper limit of normal. However, the recent discovery of a single nucleotide polymorphism(SNP), rs11559024 in the CKM gene results in an inability to produce skeletal muscle type CK and therefore low levels of CK in clinical scenarios that may result in crucial diagnosis such as rhabdomyolysis and statin-induced myositis being missed.