 Chinese males of their third and forth decades are extremely predisposed to periodic paralysis when they are hyperthyroid. Due to their imbalanced predilection to the disease, genetic variance is considered to be critical to the pathogenesis. In addition, since proximal limb skeletal muscles are the major sites of target, and they are also believed to play a role in the disease generation. Thus, we intend to analyze the genetic and morphological variances between TPP patients and pure hyperthyroidism patients and simultaneously the relation between genetic variance and morphological difference. In this way, we hope to provide evidence for a better understanding of the disease. 