A clinical and genetic study of three families with simple febrile seizures (FS) and an autosomal dominant (AD) trait with high penetrance is reported from the Hopital Pitie-Salpetriere, Paris, France. Among 29 affected family members, FS ceased before 5 years of age, only one had rare afebrile seizures in addition, and none developed epilepsy. A genome-wide scan in two famiies identified a new locus on chromosome 6q22-q24. This linkage was absent in the third family, supporting genetic heterogeneity of the AD form of simple FS. 
COMMENT. This mapping to 6q22-q24 is the first identified locus responsible for simple febrile seizures. Identification of the gene is ongoing. This phenotype differs from the known loci reported for FS and GEFS+. All modes of inheritance have been described, autosomal dominant, autosomal recessive and polygenic.
A nonsense mutation of the MASS1 gene is reported in a family with febrile and afebrile seizures, from University of Tsukuba, Ibaraki, Japan.