THE STRUCTURE AND ORGANIZATION OF THE HUMAN NPAT GENE

Ataxia telangiectasia (AT) is an autosomal recessive gene disorder, an d ATM, a housekeeping gene, has been identified as the gene responsibl e for AT. Recently we found that another housekeeping gene, NPAT: is l ocated upstream of ATM on human chromosome II. The two housekeeping ge nes are transcribed in opposite directions and share a 0.5-kb 5' flank ing sequence. The structure and organization of NPAT were determined b y direct sequencing of cosmid clones carrying the gene and by applicat ion of the long and accurate (LA)-PCR method to amplify regions encomp assing the exon/intron boundaries and all of the exons. The gene spans at least 44 kb and consists of 18 exons and 17 introns. It has been s uggested that AT heterozygotes have an Increased risk of developing ca ncel; especially breast cancer in women, Frequently, loss of heterozyg osity at loci on 11q22-q24 has been observed in DNA isolated from tumo rs of the breast, uterine cervix, and colon, perhaps suggesting the lo cation of a tumor suppressor gene in 11q22-q24. For investigation of t he role of NPAT in AT and these tumors with allelic; loss of 11q22-q24 , appropriate primer sequences and PCR conditions for amplification of all the NPAT exons from genomic DNA were determined, We previously re ported that no recombinations are found among Atm, Npat, and Acat1 (ac etoacetyl-CoA thiolase) loci as determined by fine genetic linkage map ping of the mouse AT region. The results of the LA-PCR analysis using NPAT- and ACAT-specific primers and human genomic DNA allowed us to ma p ACAT 12 kb centromeric to NPAT. (C) 1997 Academic Press.