As serum CPK are almost always within normal limits, it is not difficult to exclude most causes of myopathy that can present with ptosis and diplopia, such as myotonic muscular dystrophy and myositis [45,46]; however, some kind of myopathy may present with normal serum CPK: this is the case of oculopharingeal muscular dystrophy (OPMD) and Chronic Progressive External Ophtalmoparesis (CPEO) [47,48,49]. This evidence concerns the gene PIK3C2A and External ophthalmoplegia.