LOCALIZATION OF A PUTATIVE HUMAN BRAIN SODIUM-CHANNEL GENE (SCN1A) TOCHROMOSOME BAND 2Q24

We have identified four putative human sodium channel gene sequences, 55 bp each, using the polymerase chain reaction (PCR) on total human p lacental DNA with primers specific for the cDNA sequence of the rat br ain sodium channel Ia (Scn1a) gene. One of these sequences was extende d bidirectionally by genomic inverse-PCR to obtain a 1.6-kb fragment. Sequencing of this 1,556-bp fragment showed a 282-bp complete exon, wh ich has 95% and 94% homology at the nucleotide and amino acid levels, respectively, with the rat Scn1a gene. We putatively assign this seque nce as belonging to the gene coding the a-subunit of a human brain typ e I sodium channel (SCN1A). PCR on human x rodent somatic cell hybrids with primers derived from SCN1A localized this gene to chromosome 2. Fluorescence in situ hybridization to human metaphase chromosomes subl ocalized the gene to chromosome band 2q24.