Several tumor suppressor genes are located within human chromosome 11q23 region. We have cloned and characterized MFRP and RNF26 genes at 11q23.3. We also identified and characterized KIAA1735/MTHDIX gene at 11q23.1 and CLDN24 gene at 11q23.2 by using bioinformatics. Here, a novel human gene corresponding to a 5'-truncated FLJ20535 cDNA was identified. FLJ20535 corresponded to nucleotide position 55-2255 of FLJ13859, and nucleotide position 52-2169 of FLJ13859 was the coding region. Because of tetratricopeptide repeat (TPR) and armadillo repeat (ARM) domains within its gene product, the novel human gene was designated TPARM. Mouse E330017O07Rik cDNA was derived from mouse Tparm gene. Human TPARM (705 aa) and mouse Tparm (704 aa), showing 75.4% total-amino-acid identity, consist of TPR domain and three ARM domains. TPR domain of TPARM was most homologous to that of SMAP1, while ARM1-ARM3 domains of TPARM were most homologous to ARM7-ARM9 domains of CTNNB1 (also known as beta-catenin). TPARM might be implicated in the WNT-beta-catenin signaling pathway. TPARM mRNA was expressed in testis, prostate, lung, germinal center B-cells, and also in neuroblastoma, teratocarcinoma, colon cancer, and gastric cancer. Human TPARM gene was found to consist of 22 exons. TPARM gene, located between NCAM1 and DRD2 genes, was mapped to human chromosome 11q23.2. TPARM as well as NCAM1 and DRD2 were predicted to be candidate tumor suppressor genes within the commonly deleted region of malignant melanoma on 11q23.1-q23.2 (between microsatellite markers D11S1347 and D11S4122).