Functional variants of OCTN cation transporter genes are associated with Crohn disease.

Crohn disease is a chronic, inflammatory disease of the gastrointestinal tract. A locus of approximately 250 kb at 5q31 (IBD5) was previously associated with susceptibility to Crohn disease, as indicated by increased prevalence of a risk haplotype of 11 single-nucleotide polymorphisms among individuals with Crohn disease, but the pathogenic lesion in the region has not yet been identified. We report here that two variants in the organic cation transporter cluster at 5q31 (a missense substitution in SLC22A4 and a G-->C transversion in the SLC22A5 promoter) form a haplotype associated with susceptibility to Crohn disease. These variants alter transcription and transporter functions of the organic cation transporters and interact with variants in another gene associated with Crohn disease, CARD15, to increase risk of Crohn disease. These results suggest that SLC22A4, SLC22A5 and CARD15 act in a common pathogenic pathway to cause Crohn disease.

Pharmacogenetics in the management of breast cancer -- prospects for individualised treatment.

Increased understanding of how variants in genes encoding metabolising enzymes, transporters and receptors affect drug efficacy and toxicity, in parallel with advances in genotyping technology means that clinical pharmacogenetics is drawing tantalisingly close to reality. This review considers some of the pharmacogenetic variants that have been described that are relevant to the management of women with breast cancer and how these may soon translate into clinical practice.

Eisenmenger syndrome and atrial septal defect: nature or nurture?

BACKGROUND: It has long been debated whether patients with atrial septal defect (ASD) Eisenmenger syndrome have idiopathic pulmonary arterial hypertension with an incidental ASD or severe pulmonary hypertension on the basis of their ASD shunt magnitude alone. HYPOTHESIS: It was hypothesized that if ASD Eisenmenger patients had idiopathic pulmonary arterial hypertension with an incidental ASD, a mutation in the bone morphogenetic protein receptor-2 (BMPR2) would be found in some of these patients. PATIENTS AND METHODS: All adult patients with ASD Eisenmenger syndrome were identified from the databases of two adult congenital cardiac units, and were matched to a control group with similar types of ASDs and no pulmonary hypertension. Gene coding for BMPR2 was examined for mutation using denaturing high-performance liquid chromatography of the entire coding sequence. RESULTS: Eighteen adult patients with ASD Eisenmenger syndrome and 18 control patients were identified. ASD Eisenmenger patients had significantly larger ASDs than the control patients (3.7+/-1.2 cm versus 1.9+/-0.7 cm, P<0.01). A mutation in BMPR2 was not detected in either group. CONCLUSION: ASD Eisenmenger syndrome may occur without BMPR2 mutation. Whether shunt magnitude alone or in combination with yet another genetic mutation is responsible for the development of pulmonary hypertension in these patients remains to be determined.

Annexin VIII is differentially expressed by chondrocytes in the mammalian growth plate during endochondral ossification and in osteoarthritic cartilage.

Endochondral ossification is the developmental process that leads to the formation and coordinated longitudinal growth of the majority of the vertebrate skeleton. Central to this process is chondrocyte differentiation occurring in the growth plate that lies at the junction between the epiphyseal cartilage and the bone. To identify novel factors involved in this differentiation process, suppression subtractive hybridization was performed to amplify preferentially cDNAs uniquely expressed in fetal bovine growth plate chondrocytes as opposed to epiphyseal chondrocytes. The subtracted product was used to screen a fetal bovine chondrocyte cDNA library. One of the cDNA clones identified encoded the bovine orthologue of annexin VIII, a protein not previously described in the growth plate. Northern and Western blotting confirmed that annexin VIII was expressed by growth plate chondrocytes and not by epiphyseal chondrocytes. Immunohistochemistry of the fetal bovine growth plate identified a gradient of increasing annexin VIII protein from the proliferative to the hypertrophic zone. Immunofluorescence localized annexin VIII largely to the chondrocyte cell membrane. In a preliminary study, we examined the distribution of annexin VIII in normal and osteoarthritic (OA) articular cartilage. In OA cartilage, the protein was located in a subset of mid- to deep zone chondrocytes and in the matrix surrounding these cells; no annexin VIII was detected in normal articular cartilage. Thus annexin VIII is a marker for chondrocyte differentiation during normal endochondral ossification and may act as a marker for cells undergoing inappropriate differentiation in OA.

Tarantula hair keratitis.

We describe a 12-year-old boy in England with keratitis secondary to tarantula hairs embedded within the stroma of his cornea. Every attempt must be made to isolate these hairs at the first visit as they have a barbed nature and have a propensity to propagate through ocular tissues. A chronic keratitis requiring long-term steroid use may result if hairs persist in the cornea. Children who keep tarantulas as pets should be instructed on safe handling to prevent the tarantula from adopting defence mechanisms and shedding their hairs.

Recent advances in the genetics of inflammatory bowel disease.

PURPOSE OF REVIEW: This review addresses recent advances in the mapping and characterization of susceptibility genes for inflammatory bowel disease. The article discusses current information on the relation between CARD15 variants and Crohn disease and the discoveries of SLC22A4/SLC22A5 and DLG5 gene variants that also confer risk for inflammatory bowel disease. RECENT FINDINGS: Much of the recent emphasis in inflammatory bowel disease genetics research has been directed at evaluation of candidate disease susceptibility genes within inflammatory bowel disease linkage intervals. Such studies have elucidated associations of numerous gene variants with inflammatory bowel disease, but most of these require further replication and functional validation. Dissection of the molecular events coupling CARD15 mutation to Crohn's disease has also been intensively investigated and, while not resolved as of yet, has significantly advanced understanding of the intestinal immune response to microbial challenge. SUMMARY: The application of genetic information to diagnosis and risk prediction in inflammatory bowel disease will require comprehensive knowledge of the relevant susceptibility alleles. However, the genetic data accrued in recent years have already provided major insight into the pathophysiology of inflammatory bowel disease and identified a number of potential molecular targets for therapeutic intervention.

A risk haplotype in the Solute Carrier Family 22A4/22A5 gene cluster influences phenotypic expression of Crohn's disease.

BACKGROUND AND AIMS: Previously, we identified 2 functionally relevant polymorphisms in the SLC22A4 / 22A5 genes at the IBD5 locus that alter gene/protein function and comprise a 2-allele haplotype ( SLC22A -TC) associated with increased risk for Crohn's disease (CD). Here we examine the contribution of this susceptibility haplotype alone and in combination with CARD15 variants to CD subphenotypes and to susceptibility to ulcerative colitis (UC). METHODS: Phenotype-genotype associations were evaluated in a Canadian cohort including 507 patients with CD, 216 patients with UC, and 352 ethnically matched controls genotyped for SLC22A4 C1672T, SLC22A5 G-207C, and the major CD-associated CARD15 variants. RESULTS: The SLC22A -TC haplotype was strongly associated ( P < .0001) with CD in the non-Jewish subgroup of this cohort, and the combination of SLC22A -TC homozygosity and one or more of the common CARD15 disease susceptibility alleles engendered a 7.5-fold increase in risk for CD ( P = 9 x 10 -8 ) and a 4.5-fold increase in risk for ileal disease ( P = .001). The risk haplotype showed only a suggestive association with CD in the Jewish subgroup and no association with UC in the cohort or in subgroups stratified by CARD15 genotypes. CONCLUSIONS: The SLC22A -TC haplotype acts together with CARD15 disease susceptibility alleles to increase risk for CD and ileal disease among CD patients but does not contribute to risk for UC in this Canadian cohort. The association of the SLC22A -TC haplotype and CARD15 alleles with ileal disease suggests that these variants have biologically intertwined effects in the pathogenesis of CD.

Evidence for common genetic control in pathways of inflammation for Crohn's disease and psoriatic arthritis.

OBJECTIVE: Clinical, pharmacologic, and epidemiologic evidence supports the hypothesis that common genetic pathways may underlie inflammatory diseases. In a previous study, a Crohn's disease gene, CARD15, was demonstrated to be associated with psoriatic arthritis (PsA). Recently, a functional haplotype of 2 single-nucleotide polymorphisms (SNPs) mapping to the organic cation transporter (OCTN) genes, SLC22A4 and SLC22A5, was identified as a second Crohn's disease susceptibility locus. The SLC22A4 gene has also been associated with rheumatoid arthritis. This study was undertaken to further elucidate associations of PsA with Crohn's disease susceptibility genes. METHODS: Association with CARD15 and OCTN was investigated in UK Caucasian patients with PsA (n = 472) and population controls (n = 594), using 5' allelic discrimination assays (TaqMan). Two SNPs in OCTN, forming a haplotype previously associated with Crohn's disease, were also tested in patients with psoriasis (n = 218) and patients with early undifferentiated inflammatory arthritis (n = 386). Allele and estimated haplotype frequencies were compared between patients and controls. RESULTS: No association of PsA with CARD15 was detected. In contrast, a functional SNP mapping to the promoter region of SLC22A5 (rs2631367) was associated with PsA (for CC versus GG, odds ratio 1.65, 95% confidence interval 1.13-2.41, uncorrected P = 0.005). In addition, the haplotype associated with Crohn's disease was also associated with PsA (P = 0.001). No association was detected in the cohort with psoriasis alone or in the cohort with undifferentiated inflammatory arthritis. CONCLUSION: The OCTN haplotype previously associated with Crohn's disease is also associated with PsA, suggesting that these 2 diseases may share some common genetic control in pathways of inflammation.

SLC22A4 polymorphisms implicated in rheumatoid arthritis and Crohn's disease are not associated with rheumatoid arthritis in a Canadian Caucasian population.

OBJECTIVE: Single-nucleotide polymorphisms (SNPs) in the SLC22A4 gene encoding the organic cation transporter OCTN1 have been associated with rheumatoid arthritis (RA) in the Japanese population and with Crohn's disease in a Canadian cohort. The RA-associated and Crohn's disease-associated SNPs include, respectively, an intronic variant (slc2F2) and an exonic variant (1672T). We used a case-control approach to investigate the prevalence of these variants in a Canadian RA cohort and to determine whether RA and Crohn's disease share SLC22A4 susceptibility alleles. METHODS: Nine hundred eighteen unrelated patients with RA, 507 patients with Crohn's disease, and 623 healthy controls were genotyped for the putatively RA-associated slc2F1 and slc2F2 variants and the Crohn's disease-associated SLC22A4 1672T variant. RESULTS: Neither slc2F1 nor slc2F2 showed evidence for association with RA, the allele frequencies of these variants being significantly different in the Canadian population compared with those reported in the Japanese population, but not significantly different between patients with RA and controls. In addition, associations between the 1672T Crohn's disease risk allele and RA or between the slc2F1-A and slc2F2-T risk alleles and Crohn's disease were not detected in this study cohort, and the latter 2 alleles were not in linkage disequilibrium with the 1672T variant. CONCLUSION: These observations do not support roles for any of the previously identified SLC22A4 disease risk alleles in RA susceptibility in the Canadian population. The slc2F1/slc2F2 risk alleles were not associated with Crohn's disease nor in linkage disequilibrium with the Crohn's disease-associated 1672T variant, and accordingly, also appear to be irrelevant to Crohn's disease susceptibility in the population under study.

Association of the lymphoid tyrosine phosphatase R620W variant with rheumatoid arthritis, but not Crohn's disease, in Canadian populations.

OBJECTIVE: A single-nucleotide polymorphism in the PTPN22 gene encoding the lymphoid protein tyrosine phosphatase (Lyp) has recently been identified as a functional variant associated with susceptibility to rheumatoid arthritis (RA), type 1 diabetes, and systemic lupus erythematosus. To determine whether association of this variant (PTPN22 1858T) with RA is reproducible and is also observed in another autoimmune condition, Crohn's disease, we investigated the association between the PTPN22 1858T allele and RA and Crohn's disease in a Canadian population. METHODS: Two RA case-control cohorts representing a total of 1,234 patients and 791 healthy controls as well as a cohort of 455 patients with Crohn's disease and 190 controls were genotyped for the PTPN22 C1858T polymorphism, and genotype frequencies were compared between patients and controls. RESULTS: Significant association of the PTPN22 1858T allele with RA was detected in both the Toronto-based RA cohort (P = 1.6 x 10(-6), odds ratio [OR] 1.8) and the Halifax-based RA cohort (P = 9.4 x 10(-4), OR 1.94). Association of the risk allele with RA was not affected by sex, age at disease onset, or the presence of either rheumatoid factor or rheumatoid nodules. No association between the PTPN22 risk allele and Crohn's disease was detected. CONCLUSION: These observations confirm the association of RA susceptibility with the PTPN22 1858T allele. However, the data also reveal a lack of association between this variant and Crohn's disease, suggesting that the PTPN22 1858T allele is a risk allele for multiple, but not all, autoimmune diseases.

Inflammatory bowel disease: Crohn's disease and the success of NODern genetics.

The inflammatory bowel diseases (IBDs), Crohn's disease and ulcerative colitis, are multifactorial in etiology, but a major causative role for genetic factors has long been recognized. Recent advances in genetic technologies have made dissection of the genes underlying common diseases possible; consequently, there is an emerging understanding of the inherited factors that predispose to IBD. In this review, we summarize current information on the genetics of IBD, emphasizing the discovery of CARD15 variants as susceptibility alleles for Crohn's disease and the impact of this discovery on patient care and in delineating pathogenesis of this complex disease.

Is osteoarthritis a genetic disease?

Osteoarthritis (OA) is a common, disabling condition of diarthrodial joints. For over 60 years there has been evidence that inherited factors are important in its etiology. The research to identify these genetic factors has been driven by the need to establish markers of disease onset and progression to help clinical management and by the need to discover new disease targets for drug design. Both candidate gene studies and genome wide scanning have been undertaken and have provided some important initial results, which are considered in this review. How the research to identify OA susceptibility genes will progress and the use of new technologies to facilitate this are discussed.

NOD2/CARD15 gene mutation is not associated with susceptibility to Wegener's granulomatosis.

OBJECTIVE: Polymorphisms and mutations in the NOD2/CARD15 gene have been reported to increase susceptibility to Crohn's disease (CD) and the rare Blau syndrome, respectively. Both conditions are characterized by granuloma formation. We assessed the influence of variants in the CARD15 gene in another disorder characterized by granuloma, Wegener's granulomatosis (WG). METHODS: Direct DNA sequencing of the CARD15 gene was performed on 25 patients with WG, and an additional 73 patients were genotyped for the 3 CD associated variants, R702W, G908R, and fs1007. RESULTS: In the WG patients, 10 previously reported single nucleotide polymorphisms (SNP) were identified. No SNP were present in the WG patients at significantly different frequencies than the control population. CONCLUSION: Our data provide no evidence to support an association between CARD15 and WG.

CARD15 and HLA DRB1 alleles influence susceptibility and disease localization in Crohn's disease.

OBJECTIVES: Crohn's disease (CD) is a chronic inflammatory disease of the gut associated with allelic variants of CARD15 and HLA-DRB1 genes. We investigated the prevalence and effects of these variants in a Canadian CD cohort. METHODS: 507 unrelated CD patients were genotyped for the three major CD-associated variants (Arg702Trp, Gly908Arg, and Leu1007fsinsC) and for thirteen HLA-DRB1 alleles. RESULTS: At least one CARD15 variant was present in 32.5% of the CD patients compared with 20% of controls. The prevalence of CARD15 mutation was similar in both sporadic and familial and Jewish and non-Jewish CD patients. The Gly908Arg variant was significantly higher and the Arg702Trp variant significantly lower in Jewish compared to non-Jewish patients. A positive association between the HLA-DRB1*0103 allele and CD was detected in non-Jewish, familial cases (p = 0.0002), with risk for CD increased by 6.7 fold by the presence of an HLA-DRB1*0103 allele as compared to 1.9 fold and 19 fold by a single or two CARD15 variant alleles, respectively. We show a significant association of ileal involvement with CARD15 variants (OR = 1.8; p = 0.02), HLA-DRB1*0701 (OR = 1.9; p = 0.006) and DRB1*04 (OR = 1.7; p = 0.02) alleles and demonstrate the capacity of combined CARD15 and HLA-DRB1 genotyping to predict ileal disease in CD patients. By contrast, the HLA-DRB1*0103 allele was associated with later age of diagnosis (p = 0.02) and pure colonic disease (p = 0.000013). CONCLUSIONS: These observations confirm the influence of CARD15 and HLA-DRB1 alleles on both CD susceptibility and site of disease and identify genotyping of these variants as a potential tool for improved diagnosis and risk prediction in CD.