Clinical and genetic analysis of lipid storage myopathies

ABSTRACT: Causative genes have been identified only in four types oflipid storage myopathies (LSMs): SLC22A5 for primary carnitine deficiency(PCD); ETFA , ETFB , and ETFDH for multiple acyl-coenzyme A dehydroge-nation deficiency (MADD); PNPLA2 for neutral lipid storage disease withmyopathy (NLSDM); and ABHD5 for neutral lipid storage disease withichthyosis. However, the frequency of these LSMs has not been determined.We found mutations in only 9 of 37 LSM patients (24%): 3 in SLC22A5 ;4inMADD-associated genes; and 2 in PNPLA2 . This low frequency suggeststhe existence of other causative genes . Muscle coenzyme Q 10 levels werenormal or only mildly reduced in two MADD patients, indicating that ETFDHmutations may not always be associated with CoQ 10 deficiency. The 2patients with PNPLA2 mutations had progressive, non-episodic muscledisease with rimmed vacuoles. This suggests there is a different patho-mechanism from other LSMs. Muscle Nerve 39: 333–342, 2009 CLINICAL AND GENETIC ANALYSISOF LIPID STORAGE MYOPATHIES