Summary To gain further insight into the genetic architecture of psoriasis, we conducted a meta-analysis of three genome-wide association studies (GWAS) and two independent datasets genotyped on the Immunochip, involving 10,588 cases and 22,806 controls in total. We identified 15 new disease susceptibility regions, increasing the number of psoriasis-associated loci to 36 for Caucasians. Conditional analyses identified five independent signals within previously known loci. The newly identified shared disease regions encompassed a number of genes whose products regulate T-cell function (e.g. RUNX3, TAGAP and STAT3). The new psoriasis-specific regions were notable for candidate genes whose products are involved in innate host defense, encoding proteins with roles in interferon-mediated antiviral responses (DDX58), macrophage activation (ZC3H12C), and NF-κB signaling (CARD14 and CARM1). These results portend a better understanding of shared and distinctive genetic determinants of immune-mediated inflammatory disorders and emphasize the importance of the skin in innate and acquired host defense.

Ectodermal dysplasias comprise over 150 syndromes of unknown pathogenesis. X-linked anhidrotic ectodermal dysplasia (EDA) is characterized by abnormal hair, teeth and sweat glands. We now describe the positional cloning of the gene mutated in EDA. Two exons, separated by a 200-kilobase intron, encode a predicted 135-residue transmembrane protein. The gene is disrupted in six patients with X;autosome translocations or submicroscopic deletions; nine patients had point mutations. The gene is expressed in keratinocytes, hair follicles, and sweat glands, and in other adult and fetal tissues. The predicted EDA protein may belong to a novel class with a role in epithelial-mesenchymal signalling.

A major transport function of the human intestine involves the absorption of chloride in exchange for bicarbonate. We have studied a recessively inherited defect of this exchange, congenital chloride diarrhoea (CLD; MIM 214700). The clinical presentation of CLD is a lifetime, potentially fatal diarrhoea with a high chloride content. The CLD locus was previously mapped to 7q3 adjacent to the cystic fibrosis gene (CFTR). By refined genetic and physical mapping, a cloned gene having anion transport function, Down-regulated in adenoma (DRA), was implicated as a positional and functional candidate for CLD. In this study, we report segregation of two missense mutations, delta V317 and H124L, and one frameshift mutation, 344delT, of DRA in 32 Finnish and four Polish CLD patients. The disease-causing nature of delta V317 is supported by genetic data in relation to the population history of Finland. By mRNA in situ hybridization, we demonstrate that the expression of DRA occurs preferentially in highly differentiated colonic epithelial cells, is unchanged in Finnish CLD patients with delta V317, and is low in undifferentiated (including neoplastic) cells. We conclude that DRA is an intestinal anion transport molecule that causes chloride diarrhoea when mutated.

A second distinct family of anion exchangers, SLC26, in addition to the classical SLC4 (or anion exchanger) family, has recently been delineated. Particular interest in this gene family is stimulated by the fact that the SLC26A2, SLC26A3, and SLC26A4 genes have been recognized as the disease genes mutated in diastrophic dysplasia, congenital chloride diarrhea, and Pendred syndrome, respectively. We report the expansion of the SLC26 gene family by characterizing three novel tissuespecific members, named SLC26A7, SLC26A8, and SLC26A9, on chromosomes 8, 6, and 1, respectively. The SLC26A7-A9 proteins are structurally very similar at the amino acid level to the previous family members and show tissue-specific expression in kidney, testis, and lung, respectively. More detailed characterization by immunohistochemistry and/or in situ hybridization localized SLC26A7 to distal segments of nephrons, SLC26A8 to developing spermatocytes, and SLC26A9 to the lumenal side of the bronchiolar and alveolar epithelium of lung. Expression of SLC26A7-A9 proteins in Xenopus oocytes demonstrated chloride, sulfate, and oxalate transport activity, suggesting that they encode functional anion exchangers. The functional characterization of the novel tissue-specific members may provide new insights to anion transport physiology in different parts of body.The systematic characterization of gene families using full genome sequences provides a rich source for expanding our physiological understanding of body functions. Recently, a second distinct family of anion exchangers, SLC26, has been delineated. The members of the SLC26 1 family are structurally well conserved across different species and can mediate the electroneutral exchange of Cl Ϫ for HCO 3 Ϫ across the plasma membrane of mammalian cells like members of the classical SLC4 (anion exchanger) family (1-3). Specific interest in the SLC26 gene family is stimulated by the fact that the first three human genes are associated with phenotypically distinct recessive diseases. The SLC26A2, SLC26A3, and SLC26A4 genes have been recognized as disease genes mutated in diastrophic dysplasia, congenital chloride diarrhea, and Pendred syndrome, respectively (4 -6). Thus, the three closely related but highly tissue-specific human anion transporters play central roles in the etiology of phenotypically very different recessive diseases.In human, six tissue-specific genes of the SLC26 family have been cloned so far, namely SLC26A1-A4 (previously known as SAT-1, DTDST, CLD or DRA, and PDS, respectively), SLC26A6, and TAT1. The SLC26A2-A4 members have been shown to transport, with different specificities, the chloride, iodide, bicarbonate, oxalate, and hydroxyl anions (7-12). SLC26A5 has been cloned from gerbil and rat and shown to act as a motor protein of cochlear outer hair cell; it is sensitive to intracellular anions but has not been found to act as a transporter (13,14). The SLC26A6 protein is expressed at highest levels in the kidney and the pancreas and suggested SLC26A6 as a candidate for a yet u...

delta F508 is the most frequent cystic fibrosis (CF) mutation and accounts for approximately 70% of CF chromosomes worldwide. Three highly polymorphic microsatellite markers have been used to study the origin and evolution of delta F508 chromosomes in Europe. Haplotype data demonstrate that delta F508 occurred more than 52,000 years ago, in a population genetically distinct from any present European group, and spread throughout Europe in chronologically distinct expansions, which are responsible for the different frequencies of delta F508 in Europe.