Genomic Organization and Partial Duplication of the Human α7 Neuronal Nicotinic Acetylcholine Receptor Gene (CHRNA7)

The human α7 neuronal nicotinic acetylcholine receptor gene (HGMW-approved symbol CHRNA7) has been characterized from genomic clones. The gene is similar in structure to the chick α7 gene with 10 exons and conserved splice junction positions. The size of the human gene is estimated to be larger than 75 kb. A putative promoter 5′ of the translation start in exon 1 has been cloned and sequenced. The promoter region lacks a TATA box and has a high GC content (77%). Consensus Sp1, AP-2, Egr-1, and CREB transcription factor binding sites appear to be conserved between bovine and human genes. The α7 nAChR gene was found to be partially duplicated, with both loci mapping to the chromosome 15q13 region. A yeast artificial chromosome contig was constructed over a genetic distance of 5 cM that includes both α7 loci and the region between them. Four novel exons are described, located in genomic clones containing the partially duplicated gene. The duplicated sequences, including the novel exons, are expressed in human brain.