Abstract: Familial periodic paralysis (PP) is an autosomal dominant disorder characterized by episodic attacks of paralysis of varying severity. We recruit a normoKPP family from Hubei China to evaluate genetic variations responsible for it. Linkage analysis was performed through microsatellite markers. Markers flanking SCN4A showed linkage evidence in the family. Sequencing of SCN4A exons identified a substitution C2188T, which leading to the mutation Thr704Met, in all affected family members, and was not observed in unaffected members of the family, and 100 unrelated, control individuals. This mutation should be responsible for normoKPP in this family.