Dominant-inherited hypokalemic periodic paralysis in a large Chinese family.
Familial hypokalemic periodic paralysis (HoPP) is a rare condition among Chinese. We studied a large Chinese family (48 members in six generations) with dominant-inherited HoPP, using incidental tracing of family history of a proband who presented with the typical features of HoPP. Fifteen family members were found to have the disease. We found the familial type of HoPP to differ from the sporadic type in Taiwan, in that the familial type has an equal gender distribution, earlier onset of paralytic attacks, and more severe clinical features in both frequency and extent. When these patients were compared with Caucasian families, the common features were the involvement of the respiratory and the bulbar muscles, and the eye muscles in Chinese patients. Cold-induced attacks and permanent muscle weakness were not common in Chinese subjects. Age and history of paralytic attacks were not the major determinants for the development of permanent muscle weakness. Two family members died during attacks because of severe involvement of the respiratory and bulbar muscles.