Fine Mapping Of A Novel Non-Syndromic Postaxial Polydactyly Locus And Critical Region Analysis

Strategy of positional cloning was used to localize the locus of an autosomal dominant non-syndromic postaxial polydactyly. Fine mapping was performed and critical region was determined. Coding regions in several candidate genes were sequenced for mutation analysis. Also a cDNA of novel KRAB zinc finger gene, ZNF333, was characterized in the critical region of postaxial polydactyly.Two point linkage analysis was performed with microsatellite markers on genetic map of chromosome 19. The highest Lod score was 5.85 at theta=0 at microsatellite marker D19S221. Physical map of short arm region on chromosome 19 from the human working draft sequences was also analyzed and all microsatellite markers were repositioned precisely according to the BAC/cosmid sequences and the recombination events in the family. Haplotype analysis was carried out accordingly in the whole family and the disease gene was localized to a 2. 5Mb region between D19S929 and D19S1165. A family member with normal phenotype has a recombinant at marker D19S226 in the region. According to the estimates of penetrance in this family, the disease gene could be most likely located in the region from D19S840 and D19S929, which is around 1 Megabase in physical length. As locus reported in this family was different from the other two known loci, it was named as PAP-3.Through bioinformatics study, around 70 known genes and ESTs were determined and in the 1Mb region from D19S840 and D19S929, there are 24 genes. Coding regions in KLF1 (Kruppel like factor 1) , CIOT-2(gonadotropin inducible transcription repressor 2) , EMR2(epidermal growth factor like receptor2, mucin like), EMR3, OR7C1 (Olfactory receptor 7, Subfamily C, member 1) and KIAA0821(lectomedin-2)were sequenced, but no caused mutations were detected.In PAP-3 critical region, a novel KRAB zinc finger cDNA was idetified. Human Gene Nomenclature Committee named it as ZNF333(GenBank No. AF372702). ZNF333 contains 12 exons, encoding a putative protein of 665 amino acids.