ASSIGNMENT OF HUMAN GENES FOR BETA-2 AND BETA-4 SUBUNITS VOLTAGE-DEPENDENT CA2-Q23( CHANNELS TO CHROMOSOMES 10P12 AND 2Q22)

We have used human beta 2 and beta 4 cDNA probes to map the genes enco ding two isoforms of the regulatory beta subunit of voltage-activated Ca2+ channels, viz. CACNB2 (beta 2) and CACNB4 (beta 4), to human chro mosomes 10p12 and 2q22-q23, respectively, by fluorescence in situ hybr idization. The gene encoding the beta 2 protein, first described as a Lambert-Eaton myasthenic syndrome (LEMS) antigen in humans, is found c lose to a region that undergoes chromosome rearrangements in small cel l lung cancer, which occurs in association with LEMS. CACNB2 (beta 2) and CACNB4 (beta 4) genes are members of the ion-channel gene superfam ily and it should now be possible to examine their loci by linkage ana lysis of ion-channel-related disorders. To date, no such disease-relat ed gene has been assigned to 10p12 and 2q22-q23.