POSTER NO: 168

Large-scale cSNP genotyping in the Down Syndrome Critical Region of chromosome 21

¹S.M. Demiya, ²H. Hagiwara, ¹T.D. Taylor, ¹A. Toyoda, ³W. Pornswan, ¹Y. Sakaki
¹RIKEN GSC, Human Genome Research Group, 4th Fl., West Bldg.,1-7-22 Suehiro-cho,Tsurumi-ku,Yokohama, Kanagawa, 230-0045 Japan, ²Hitachi Electronics Engneering Co.,Ltd., Bio-Systems Equipment Design Department, 16-3, Higashi 3-chome, Shibuya-ku, Tokyo, 150-0011 Japan, ³Mahidol University, Siriraj Hospital Faculty of Medicine, Department of Peidatrics, Divison of Medical Genetics, Bangkok, Thailand

Since the sequence of chromosome 21 is published and available in various databases, new genes were predicted. Currently 307 genes are described in chromosome 21 including known human genes, novel genes with similarities over their total length of cDNA, genes with similarities to a confined protein region, in silico predicted genes and pseudogenes. Among these described 307 genes we focused on a particular region, the so-called Down Syndrome Critical Region (DSRC). This segment covers about 2.6Mb of chromosome 21 and includes 20 novel and predicted genes that are potentially involved in Down Syndrome.

Single Nucleotide Polymorphisms (SNPs) are powerful assets for mapping and for finding mutations related to diseases. In the DSCR, which contains 181 coding exons, we identified at least 54 SNPs mined from the public database. The detected genes in the DSCR with various SNPs provide a powerful tool for understanding the correlation between SNPs and the clinical phenotypes of partial trisomy. As a preliminary experiment we are genotyping these potential 54 SNPs identified in exons in control samples to estimate their allele frequencies. Our target is to genotype several patients having partial or complete trisomy of chromosome 21.