Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul 151-747, Korea.|Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul 151-747, Korea.|Center for Genome Science, National Institute of Health, Osong Health Technology Administration Complex, Chungcheongbuk-Do 363-951, Korea.|Center for Genome Science, National Institute of Health, Osong Health Technology Administration Complex, Chungcheongbuk-Do 363-951, Korea.|Center for Genome Science, National Institute of Health, Osong Health Technology Administration Complex, Chungcheongbuk-Do 363-951, Korea.|Department of Psychology, McGill University, Montreal, QC H3A 1B1, Canada.|Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul 151-747, Korea Department of Statistics, Seoul National University, Seoul 151-747, Korea.