Mutation inDHP receptorcxlsubunit (CACLN1A3)gene ina Dutchfamily with hypokalaemic periodic paralysis

Hypokalaemic periodic paralysis (HypoPP)ischaracterised bytransient attacks ofmuscleweaknessofvaryingduration andseverity accompanied by a dropin serum potassium concentration during the attacks. Thelargest knownHypoPPfamily isofDutchorigin andconsists of277membersinthelast five generations, 55ofwhom haveHypoPPinherited inan autosomal dominantpattern.Forty-eight persons including 28patients witha proven diagnosis ofHypoPPwere usedforlinkage analysis. Microsatellite markerswere usedto exclude45to50%ofthegenome andlinkage to chromosome1q31-32 was found.No recombinants were foundbetweenHypoPP and DlS412and a microsatellite contained withintheDHP receptoral subunit(CACLNlA3)gene. A previously reported G toA mutationcausing an arginine tohistidine substitution atresidue 528inthetransmembrane segmentIIS4of theCACLN1A3 gene was showninpatients by restriction analysis ofgenomicPCR products. (JMedGenet1995;32:44-47)