MAPPING OF THE HYPOKALEMIC PERIODIC PARALYSIS (HYPOPP) LOCUS TO CHROMOSOME 1Q31-32 IN 3 EUROPEAN FAMILIES

Hypokalaemic periodic paralysis (HypoPP) is an autosomal dominant musc le disease thought to arise from an abnormal function of ion channels. Performing a genome-wide search using polymorphic dinucleotide repeat s, we have localized the HypoPP locus in three families of different g eographic origin to chromosome 1q31-32, by linkage analysis. Using an intragenic microsatellite, we also demonstrate that the gene encoding the muscle DHP-sensitive calcium channel al subunit(CACNL1A3) maps to the same region, sharing a 5 centiMorgan (cM) interval with the HypoPP locus. Moreover, CACNL1A3 co-segregrates with HypoPP without recombin ants in the two informative families, and is therefore a good candidat e for the HypoPP gene.