Advanced age-related macular degeneration (AMD) is the leading cause of blindness in the elderly with limited therapeutic options. Here, we report on a study of >12 million variants including 163,714 directly genotyped, most rare, protein-altering variant. Analyzing 16,144 patients and 17,832 controls, we identify 52 independently associated common and rare variants (P < 5×10–8) distributed across 34 loci. While wet and dry AMD subtypes exhibit predominantly shared genetics, we identify the first signal specific to wet AMD, near MMP9 (difference-P = 4.1×10–10). Very rare coding variants (frequency < 0.1%) in CFH, CFI, and TIMP3 suggest causal roles for these genes, as does a splice variant in SLC16A8. Our results support the hypothesis that rare coding variants can pinpoint causal genes within known genetic loci and illustrate that applying the approach systematically to detect new loci requires extremely large sample sizes.
Objective. Blau syndrome and its sporadic counterpart, early-onset sarcoidosis, share an identical phenotype featuring the classic triad of arthritis, dermatitis, and uveitis and are associated with mutations of CARD15 in 50-90% of cases. We chose the term "pediatric granulomatous arthritis" to refer to both. An international registry was established in the spring of 2005 to define the phenotype spectrum and establish the mutation frequency and variants.Methods. Histologically confirmed granuloma and arthritis were required for inclusion. Probands and relatives were genotyped for CARD15. Deidentified clinical information was collected.Results. One year after the inception of the registry, 61 individuals from 22 pedigrees had been entered. Seven pedigrees with 19 individuals (8 affected, 11 unaffected) had clinical disease that was atypical, and none of the individuals in those pedigrees showed mutations. There were 9 classic simplex pediatric granulomatous arthritis pedigrees including 19 individuals (9 affected, 10 unaffected) and 6 classic multiplex pedigrees with 22 individuals (17 affected, 5 unaffected). Cutaneous presentation was the most common. Arthritis was polyarticular in 96% of patients. Isolated eye disease was never the presenting symptom, but significant/severe visual impairment was observed in 41% of patients. Eye disease was bilateral in 21 of 22 patients and was complicated by glaucoma in 6 of 22 patients and by cataracts in 50% of patients. Skin biopsy was the best diagnostic approach (because of accuracy and low invasiveness).Conclusion. In this series, the first combining familial and sporadic pedigrees and, to our knowledge, the largest, we further defined the phenotype and showed that all affected classic (and no nonclassic) pedigrees carry a mutation and that there is no asymptomatic carriage. If these data are confirmed, mutation analysis rather than tissue sampling may prove to be the most efficient diagnostic procedure.
TINU syndrome is strongly associated with HLA-DQA1*01, HLA-DQB1*05, and HLA-DRB1*01. The association with HLA-DRB1*0102 is one of the highest reported for any disease. Because these genes are in linkage disequilibrium, the role of the individual alleles is difficult to assess. Based on the results of the present study and on previously reported HLA associations in patients with TINU syndrome, the alphabeta dimer encoded by HLA-DQA1*01/DQB1*05 may be particularly important in conferring risk for development of this disease.
Objective. To study the phenotype characteristics of the largest to date cohort of patients with pediatric granulomatous arthritis (PGA) and documented mutations in the NOD2 gene.Methods. We analyzed merged data from 2 prospective cohorts of PGA patients, the International PGA Registry and a Spanish cohort. A systematic review of the medical records of interest was performed to identify phenotype characteristics.Results. Forty-five patients with PGA (23 sporadic cases and 22 from familial pedigrees) and documented NOD2 mutations were identified and formed the basis of the study. Of these 45 patients, 18 had the R334W-encoding mutation, 18 had R334Q, 4 had E383K, 3 had R587C, 1 had C495Y, and 1 had W490L.The majority of patients manifested the typical triad of dermatitis, uveitis, and arthritis. In contrast, in 13 patients, the following "atypical" manifestations were noted: fever, sialadenitis, lymphadenopathy, erythema nodosum, leukocytoclastic vasculitis, transient neuropathy, granulomatous glomerular and interstitial nephritis, interstitial lung disease, arterial hypertension, hypertrophic cardiomyopathy, pericarditis, pulmonary embolism, hepatic granulomatous infiltration, splenic involvement, and chronic renal failure. In addition, 4 individuals who were asymptomatic carriers of a disease-causing mutation were documented.Conclusion. NOD2-associated PGA can be a multisystem disorder with significant visceral involvement. Treating physicians should be aware of the systemic nature of this condition, since some of these manifestations may entail long-term morbidity.Pediatric granulomatous arthritis (PGA) encompasses 2 diseases with an identical phenotype, the autosomal-dominant Blau syndrome and early-onset sarcoidosis, a sporadic condition. The finding of identical mutations on exon 4 of the NOD2 gene supports the notion that these diseases are actually the same (1-3). Blau (4) described the syndrome that bears his name as a triad of granulomatous boggy polyarthritis, uveitis, and papuloerythematous rash, whereas Jabs et al (5) described a polyarthritis with uveitis, without rash, but with cranial neuropathy. Early-onset sarcoidosis has been known since the 1970s, and like Blau syndrome, it is characterized by granulomatous boggy synovitis, uveitis, and rash, which is indistinguishable from Blau syndrome, albeit without a familial component (6).
Age-related macular degeneration (AMD) is a common cause of severe vision loss. Identification of the genes involved in AMD will lead to a better understanding of this disease at the molecular level, which will eventually lead to early detection, prevention and treatment. Previously, we mapped the ARMD1 gene to 1q25-31 in a large family with AMD. Here, we narrow the ARMD1 locus to 14.9 Mb between LAMB2 and D1S3469, a region containing 50 known genes. Twenty candidate genes within this region were screened for mutations. Only one DNA variation, an A16,263G transition in exon 104 of HEMICENTIN-1, was found to segregate exclusively with the disease haplotype in members of this large family with AMD. This variation produces a non-conservative substitution of arginine for glutamine at amino acid position 5345 (Gln5345Arg). It was also identified in 11 other individuals, all of whom share a haplotype, which envelops HEMICENTIN-1, with the large AMD family. The affected status of all but one of those individuals conforms to the age-dependent penetrance observed in AMD. The amino acid at position 5345 of HEMICENTIN-1 was conserved as glutamine in eight species analyzed. RT-PCR analysis demonstrated that exon 104 of HEMICENTIN-1 is alternatively spliced in various cell types. Exclusive segregation of Gln5345Arg with the disease haplotype in this large family, amino acid conservation of glutamine at this position among mammals, the non-conservative nature of the substitution and similarities to EFEMP1 support the conclusion that HEMICENTIN-1 is the ARMD1 gene.
Elucidation of downstream effects of NOD2 mutations could provide valuable clues to mechanisms of arthritis and uveitis in general as well as granulomatous diseases in particular.
Objective To use high density genotyping to investigate the genetic associations of acute anterior uveitis (AAU) in patients both with and without ankylosing spondylitis (AS). Method We genotyped 1,711 patients with AAU (either primary or with AAU and AS), 2,339 AS patients without AAU, and 10,000 controls on the Illumina Immunochip Infinium microarray. We also used data on AS patients from previous genomewide association studies to investigate the AS risk locus ANTXR2 for its putative effect in AAU. ANTXR2 expression in mouse eyes was investigated by RT-PCR. Results Comparing all AAU cases with HC, strong association was seen over HLA-B corresponding to the HLA-B27 tag SNP rs116488202. Three non-MHC loci IL23R, the intergenic region 2p15 and ERAP1 were associated at genome-wide significance (P < 5×10−8). Five loci harboring the immune-related genes IL10-IL19, IL18R1-IL1R1, IL6R, the chromosome 1q32 locus harboring KIF21B, as well as the eye related gene EYS, were also associated at a suggestive level of significance (P < 5×10−6). A number of previously confirmed AS associations demonstrated significant differences in effect size between AS patients with AAU and AS patients without AAU. ANTXR2 expression was found to vary across eye compartments. Conclusion These findings, with both novel AAU specific associations, and associations shared with AS demonstrate overlapping but also distinct genetic susceptibility loci for AAU and AS. The associations in IL10 and IL18R1 are shared with inflammatory bowel disease, suggesting common etiologic pathways.
Objective. To define the genetic basis of susceptibility to ankylosing spondylitis (AS), especially nonmajor histocompatibility complex (MHC) genes.Methods. The study group comprised 244 affected sibling pairs from 180 pedigrees of primarily European ancestry. Sibling pairs were concordant for AS by the modified New York criteria and had available sacroiliac radiographs. The subjects were genotyped for 400 markers in ABI PRISM linkage map MD-10 and for 17 additional markers on chromosomes 6p, 6q, and 11q (including HLA-B, DRB1, DQA1, DQB1, and DPB1 alleles). Two-point and multipoint nonparametric linkage (NPL) analyses were conducted using the NPL statistic and 1-parameter allele-sharing model logarithm of odds (LOD) scores, calculated using the AlleleSharing Model (ASM) computer program.Results. Linkage of the MHC region was supported by both 2-point and multipoint analyses, with the strongest peak (45.90 cM) in the MHC at the HLA-DRB1 locus (NPL score 8.720, ASM LOD score 20.49; P ؍ 6.8 ؋ 10 ؊20 for 2-point analysis). A second region was found to have positive linkage at the q arm of chromosome 6 (D6S441) in 2-point analysis; this was supported by a 39.13-cM region (135.58-174.71 cM) in multipoint analysis, with the smallest P value (4.2 ؋ 10 ؊3 ) at 166.39 cM. A third region was found on chromosome 11q, with the strongest evidence for linkage for D11S4094 at 123 cM (NPL score 2.235, ASM LOD score 1.939) and, on transmission disequilibrium test analysis, D11S4090 at 105.74 cM (P ؍ 6.2 ؋ 10 ؊5 ). Linkage in this area was supported by multipoint analysis, spanning 22.19 cM continuously from 101.68 cM to 123.87 cM, with the strongest peak at 112.33 cM (P ؍ 0.014); this was confirmed by subsequent fine mapping studies.Conclusion. Thus, this genome-wide scan implicates, in addition to the MHC, regions outside the MHC in AS susceptibility, especially on chromosomes 6q and 11q.Ankylosing spondylitis (AS) is a common chronic inflammatory disorder primarily affecting the spine, although the peripheral joints and the attachments of ligaments and tendons to joints (the entheses) are also frequently involved, as well as the eyes, and, less com-
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