Gender differences in penetrance and phenotype in hypokalemic periodic paralysis.

INTRODUCTION

Hypokalemic periodic paralysis (HypoPP) is an autosomal dominant skeletal muscle ion channelopathy. Sex hormones are natural ion channel regulators. Different sex hormones have different effects on ion channels. A comparison of the penetrance and phenotype between males and females with HypoPP mutations should aid in proving that sex hormones play different roles in HypoPP and also provide the basis for the development of therapies against HypoPP.

METHODS

We identified all mutation carriers in 4 HypoPP families using PCR sequencing techniques. All patients underwent clinical investigation.

RESULTS

There were 8 men and 7 women mutation carriers in the 4 families. Male carriers had 100% penetrance, but female penetrance was only 28.57%. The highest attack frequency was 50-150 times/year for the men, whereas it was 30-50 times/year for the women. The attacks disappeared during pregnancy.

CONCLUSIONS

The penetrance and attack frequency were lower in women than in men with HypoPP mutations.