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Thyrotoxic hypokalemic periodic paralysis (THypoKPP) is an uncommon disorder with an unknown etiology. We describe a family in which the proband presented with paralysis and thyrotoxicosis. Because of similarities between familial hypokalemic periodic paralysis (FHypoKPP) and THypoKPP, we sequenced exon 12 of the SCN4A gene, which is known to be mutated in FHypoKPP. We identified an Arg672Ser mutation in the proband and his affected father, as well as the proband's brother. As the brother has paralysis without thyrotoxicosis, our finding suggests that the genetic spectrum of FHypoKPP and THypoKPP overlap. We speculate that thyroid hormone may exert a threshold or permissive effect in hypokalemic periodic paralysis. Non-thyrotoxic family members of individuals with THypoKPP may have an unrecognized risk for paralysis.

The membrane (M1) protein of influenza virus was found to be heterogenous and to occur in two forms in the virus particle. The two forms of Ml were found in virus which was produced both early and late after infection and in infected cells. The two forms could be separated on polyacrylamide gels under specific conditions. The two components of Ml contained similar tryptic peptides. However, a small proteolytic difference between the two proteins could not be ruled out. Both Ml proteins were present in phosphorylated form in the virus particle. The phosphorylated Ml components were not readily distinguished from phosphorylated nonstructural protein (NS,) when cytoplasm of infected cells was analyzed on polyacrylamide gels. The two phosphorylated Ml components could, however, be detected in infected cells by immunoprecipitation. One Ml component contained only phosphoserine whereas the second contained phosphoserine and a small amount of phosphothreonine as well. In addition to the phosphorylated nucleoprotein and MI, a third phosphorylated protein was routinely detected in virus particles. It was a surface component of the virus, since it could be removed from whole virus with chymotrypsin and contained phosphate at serine residues. The identity of this component was not known.

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