A genome-wide association study identifies new psoriasis susceptibility loci and an interaction between HLA-C and ERAP1

To identify new susceptibility loci for psoriasis, we undertook a genome-wide association study of 594,224 SNPs in 2,622 individuals with psoriasis and 5,667 controls. We identified associations at eight previously unreported genomic loci. Seven loci harbored genes with recognized immune functions (IL28RA, REL, IFIH1, ERAP1, TRAF3IP2, NFKBIA and TYK2). These associations were replicated in 9,079 European samples (six loci with a combined P < 5 × 10?? and two loci with a combined P < 5 × 10??). We also report compelling evidence for an interaction between the HLA-C and ERAP1 loci (combined P = 6.95 × 10??). ERAP1 plays an important role in MHC class I peptide processing. ERAP1 variants only influenced psoriasis susceptibility in individuals carrying the HLA-C risk allele. Our findings implicate pathways that integrate epidermal barrier dysfunction with innate and adaptive immune dysregulation in psoriasis pathogenesis.     

Mutations in TRPV4 cause an inherited arthropathy of hands and feet

Familial digital arthropathy-brachydactyly (FDAB) is a dominantly inherited condition that is characterized by aggressive osteoarthropathy of the fingers and toes and consequent shortening of the middle and distal phalanges. Here we show in three unrelated families that FDAB is caused by mutations encoding p.Gly270Val, p.Arg271Pro and p.Phe273Leu substitutions in the intracellular ankyrin-repeat domain of the cation channel TRPV4. Functional testing of mutant TRPV4 in HEK-293 cells showed that the mutant proteins have poor cell-surface localization. Calcium influx in response to the synthetic TRPV4 agonists GSK1016790A and 4αPDD was significantly reduced, and mutant channels did not respond to hypotonic stress. Others have shown that gain-of-function TRPV4 mutations cause skeletal dysplasias and peripheral neuropathies. Our data indicate that TRPV4 mutations that reduce channel activity cause a third phenotype, inherited osteoarthropathy, and show the importance of TRPV4 activity in articular cartilage homeostasis. Our data raise the possibility that TRPV4 may also have a role in age- or injury-related osteoarthritis.     

A genome-wide association study shows that common alleles of SMAD7 influence colorectal cancer risk

To identify risk variants for colorectal cancer (CRC), we conducted a genome-wide association study, genotyping 550,163 tag SNPs in 940 individuals with familial colorectal tumor (627 CRC, 313 advanced adenomas) and 965 controls. We evaluated selected SNPs in three replication sample sets (7,473 cases, 5,984 controls) and identified three SNPs in SMAD7 (involved in TGF-beta and Wnt signaling) associated with CRC. Across the four sample sets, the association between rs4939827 and CRC was highly statistically significant (P(trend) = 1.0 x 10(-12)).     

The amino-terminal disease hotspot of ryanodine receptors forms a cytoplasmic vestibule

Many physiological events require transient increases in cytosolic Ca(2+) concentrations. Ryanodine receptors (RyRs) are ion channels that govern the release of Ca(2+) from the endoplasmic and sarcoplasmic reticulum. Mutations in RyRs can lead to severe genetic conditions that affect both cardiac and skeletal muscle, but locating the mutated residues in the full-length channel structure has been difficult. Here we show the 2.5?? resolution crystal structure of a region spanning three domains of RyR type 1 (RyR1), encompassing amino acid residues 1-559. The domains interact with each other through a predominantly hydrophilic interface. Docking in RyR1 electron microscopy maps unambiguously places the domains in the cytoplasmic portion of the channel, forming a 240-kDa cytoplasmic vestibule around the four-fold symmetry axis. We pinpoint the exact locations of more than 50 disease-associated mutations in full-length RyR1 and RyR2. The mutations can be classified into three groups: those that destabilize the interfaces between the three amino-terminal domains, disturb the folding of individual domains or affect one of six interfaces with other parts of the receptor. We propose a model whereby the opening of a RyR coincides with allosterically coupled motions within the N-terminal domains. This process can be affected by mutations that target various interfaces within and across subunits. The crystal structure provides a framework to understand the many disease-associated mutations in RyRs that have been studied using functional methods, and will be useful for developing new strategies to modulate RyR function in disease states.     

Common variants in DGKK are strongly associated with risk of hypospadias

Hypospadias is a common congenital malformation of the male external genitalia. We performed a genome-wide association study using pooled DNA from 436 individuals with hypospadias (cases) and 494 controls of European descent and selected the highest ranked SNPs for individual genotyping in the discovery sample, an additional Dutch sample of 133 cases and their parents, and a Swedish series of 266 cases and 402 controls. Individual genotyping of two SNPs (rs1934179 and rs7063116) in DGKK, encoding diacylglycerol kinase κ, produced compelling evidence for association with hypospadias in the discovery sample (allele-specific odds ratio (OR) = 2.5, P = 2.5 × 10?11 and OR = 2.3, P = 2.9 × 10??, respectively) and in the Dutch (OR = 3.9, P = 2.4 × 10?? and OR = 3.8, P = 3.4 × 10??) and Swedish (OR = 2.5, P = 2.6 × 10?? and OR = 2.2, P = 2.7 × 10??) replication samples. Expression studies showed expression of DGKK in preputial tissue of cases and controls, which was lower in carriers of the risk allele of rs1934179 (P = 0.047). We propose DGKK as a major risk gene for hypospadias.     

Oncogenic IL7R gain-of-function mutations in childhood T-cell acute lymphoblastic leukemia

Interleukin 7 (IL-7) and its receptor, formed by IL-7Rα (encoded by IL7R) and γc, are essential for normal T-cell development and homeostasis. Here we show that IL7R is an oncogene mutated in T-cell acute lymphoblastic leukemia (T-ALL). We find that 9% of individuals with T-ALL have somatic gain-of-function IL7R exon 6 mutations. In most cases, these IL7R mutations introduce an unpaired cysteine in the extracellular juxtamembrane-transmembrane region and promote de novo formation of intermolecular disulfide bonds between mutant IL-7Rα subunits, thereby driving constitutive signaling via JAK1 and independently of IL-7, γc or JAK3. IL7R mutations induce a gene expression profile partially resembling that provoked by IL-7 and are enriched in the T-ALL subgroup comprising TLX3 rearranged and HOXA deregulated cases. Notably, IL7R mutations promote cell transformation and tumor formation. Overall, our findings indicate that IL7R mutational activation is involved in human T-cell leukemogenesis, paving the way for therapeutic targeting of IL-7R-mediated signaling in T-ALL.     

Germline mutations in RAD51D confer susceptibility to ovarian cancer

Recently, RAD51C mutations were identified in families with breast and ovarian cancer. This observation prompted us to investigate the role of RAD51D in cancer susceptibility. We identified eight inactivating RAD51D mutations in unrelated individuals from 911 breast-ovarian cancer families compared with one inactivating mutation identified in 1,060 controls (P = 0.01). The association found here was principally with ovarian cancer, with three mutations identified in the 59 pedigrees with three or more individuals with ovarian cancer (P = 0.0005). The relative risk of ovarian cancer for RAD51D mutation carriers was estimated to be 6.30 (95% CI 2.86-13.85, P = 4.8 × 10(-6)). By contrast, we estimated the relative risk of breast cancer to be 1.32 (95% CI 0.59-2.96, P = 0.50). These data indicate that RAD51D mutation testing may have clinical utility in individuals with ovarian cancer and their families. Moreover, we show that cells deficient in RAD51D are sensitive to treatment with a PARP inhibitor, suggesting a possible therapeutic approach for cancers arising in RAD51D mutation carriers.     

Skint1, the prototype of a newly identified immunoglobulin superfamily gene cluster, positively selects epidermal gammadelta T cells

B cells, alphabeta T cells and gammadelta T cells are conserved lymphocyte subtypes encoding their antigen receptors from somatically rearranged genes. alphabeta T cells undergo positive selection in the thymus by engagement of their T cell receptors (TCRs) with self-peptides presented by major histocompatibility complex molecules. The molecules that select gammadelta T cells are unknown. Vgamma5+Vdelta1+ cells comprise 90% of mouse epidermal gammadelta T cells. By mapping and genetic complementation using a strain showing loss of Vgamma5+Vdelta1+ cells due to a failure of thymic selection, we show that this defect is caused by mutation in Skint1, a newly identified gene expressed in thymus and skin that encodes a protein with immunoglobulin-like and transmembrane domains. Skint1 is the prototypic member of a rapidly evolving family of at least 11 genes in mouse, with greatest similarity to the butyrophilin genes. These findings define a new family of proteins mediating key epithelial-immune interactions.