Novel Nonsense Mutation in SLC39A13 Initially Presenting as Myopathy: Case Report and Review of the Literature.

Myopathies comprise a heterogeneous group of disorders characterized by variable phenotypes. The increasing use of next-generation sequencing allows identification of the causative genes in a much higher percentage of patients with hereditary muscle disorders and also illustrates a considerable degree of overlap with other clinical entities, including connective tissue disorders. Here, we present a 14-year-old German patient who was initially suspected to suffer from myopathy based on his clinical, radiological, and muscle biopsy findings. Exome sequencing revealed a novel homozygous nonsense mutation in the SLC39A13 gene, causative for spondylocheiro dysplastic Ehlers Danlos syndrome (SCD-EDS), suggesting a connective tissue disorder. Including our patient, only 9 affected individuals from 4 families have been described for SCD-EDS so far. The previously reported patients did not show obvious evidence of myopathy, suggesting a broader clinical presentation than originally suspected. We summarize herein the current knowledge on clinical features as well as pathophysiological pathways for this rare connective tissue disease and discuss the high degree of clinical overlap between myopathic and connective tissue disorders.

Analysis of Plasminogen Genetic Variants in Multiple Sclerosis Patients.

Multiple sclerosis (MS) is a prevalent neurological disease of complex etiology. Here, we describe the characterization of a multi-incident MS family that nominated a rare missense variant (p.G420D) in plasminogen (PLG) as a putative genetic risk factor for MS. Genotyping of PLG p.G420D (rs139071351) in 2160 MS patients, and 886 controls from Canada, identified 10 additional probands, two sporadic patients and one control with the variant. Segregation in families harboring the rs139071351 variant, identified p.G420D in 26 out of 30 family members diagnosed with MS, 14 unaffected parents, and 12 out of 30 family members not diagnosed with disease. Despite considerably reduced penetrance, linkage analysis supports cosegregation of PLG p.G420D and disease. Genotyping of PLG p.G420D in 14446 patients, and 8797 controls from Canada, France, Spain, Germany, Belgium, and Austria failed to identify significant association with disease (P = 0.117), despite an overall higher prevalence in patients (OR = 1.32; 95% CI = 0.93-1.87). To assess whether additional rare variants have an effect on MS risk, we sequenced PLG in 293 probands, and genotyped all rare variants in cases and controls. This analysis identified nine rare missense variants, and although three of them were exclusively observed in MS patients, segregation does not support pathogenicity. PLG is a plausible biological candidate for MS owing to its involvement in immune system response, blood-brain barrier permeability, and myelin degradation. Moreover, components of its activation cascade have been shown to present increased activity or expression in MS patients compared to controls; further studies are needed to clarify whether PLG is involved in MS susceptibility.

Genome-wide significant association with seven novel multiple sclerosis risk loci.

OBJECTIVE: A recent large-scale study in multiple sclerosis (MS) using the ImmunoChip platform reported on 11 loci that showed suggestive genetic association with MS. Additional data in sufficiently sized and independent data sets are needed to assess whether these loci represent genuine MS risk factors. METHODS: The lead SNPs of all 11 loci were genotyped in 10 796 MS cases and 10 793 controls from Germany, Spain, France, the Netherlands, Austria and Russia, that were independent from the previously reported cohorts. Association analyses were performed using logistic regression based on an additive model. Summary effect size estimates were calculated using fixed-effect meta-analysis. RESULTS: Seven of the 11 tested SNPs showed significant association with MS susceptibility in the 21 589 individuals analysed here. Meta-analysis across our and previously published MS case-control data (total sample size n=101 683) revealed novel genome-wide significant association with MS susceptibility (p<5×10(-8)) for all seven variants. This included SNPs in or near LOC100506457 (rs1534422, p=4.03×10(-12)), CD28 (rs6435203, p=1.35×10(-9)), LPP (rs4686953, p=3.35×10(-8)), ETS1 (rs3809006, p=7.74×10(-9)), DLEU1 (rs806349, p=8.14×10(-12)), LPIN3 (rs6072343, p=7.16×10(-12)) and IFNGR2 (rs9808753, p=4.40×10(-10)). Cis expression quantitative locus effects were observed in silico for rs6435203 on CD28 and for rs9808753 on several immunologically relevant genes in the IFNGR2 locus. CONCLUSIONS: This study adds seven loci to the list of genuine MS genetic risk factors and further extends the list of established loci shared across autoimmune diseases.

Molecular Genetics of Sex Identification, Breed Ancestry and Polydactyly in the Norwegian Lundehund Breed.

The Norwegian Lundehund breed of dog has undergone a severe loss of genetic diversity as a result of inbreeding and epizootics of canine distemper. As a consequence, the breed is extremely homogeneous and accurate sex identification is not always possible by standard screening of X-chromosomal loci. To improve our genetic understanding of the breed we genotyped 17 individuals using a genome-wide array of 170 000 single nucleotide polymorphisms (SNPs). Standard analyses based on expected homozygosity of X-chromosomal loci failed in assigning individuals to the correct sex, as determined initially by physical examination and confirmed with the Y-chromosomal marker, amelogenin. This demonstrates that identification of sex using standard SNP assays can be erroneous in highly inbred individuals.

Association of variation in the LAMA3 gene, encoding the alpha-chain of laminin 5, with atopic dermatitis in a German case-control cohort.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disorder caused by complex interaction of genetic and environmental factors. Besides mutations in the filaggrin gene, leading to impaired skin barrier function, variation in genes encoding additional skin proteins has been suggested to contribute to disease risk. Laminin 5, playing an important role in skin integrity, is composed of three subunits encoded by the LAMA3, LAMB3 and LAMC2 genes in which biallelic mutations cause epidermolysis bullosa junctionalis. We aimed at evaluating the role of variation in the LAMA3, LAMB3 and LAMC2 genes for AD pathogenesis. METHODS: 29 single nucleotide polymorphisms (SNPs) were genotyped in the three genes in a German AD case-control cohort comprising 470 unrelated AD patients and 320 non-atopic controls by means of restriction enzyme digestion. Allele, genotype and haplotype frequencies were compared between cases and controls using chi-square testing and the Haploview software. RESULTS: Several SNPs in the LAMA3 gene showed significant association with AD in our cohort (p <0.01), while we did not detect association with variations in the LAMB3 and LAMC2 genes. Haplotype analysis additionally revealed several significantly associated haplotypes in the LAMA3 gene. Due to extensive linkage disequilibrium, though, we were not able to further differentiate the specific disease causing variation(s) in this region. CONCLUSIONS: We established the LAMA3 gene as novel potential susceptibility gene for AD. Additional studies in independent cohorts are needed to replicate these results.

Analysis of polymorphisms in RIG-I-like receptor genes in German multiple sclerosis patients.

Variation in genes encoding retinoid acid-inducible gene I (RIG-I)-like receptors (RLRs) has been implicated in the pathogenesis of autoimmune disorders. We investigated if polymorphisms in the IFIH1, RIG-I, LGP2 and VISA genes influence the risk for multiple sclerosis (MS) in a German case-control cohort comprising 716 patients and 706 controls. Evaluation of 18 single nucleotide polymorphisms (SNPs) in the four genes did not reveal significant single-SNP associations with MS risk, but two VISA polymorphisms were modestly associated with age of onset. Further, we provide initial evidence for combinatorial effects of polymorphic variants in the RIG-I, LGP2 and IFIH1 genes on MS risk.

Assessment of microRNA-related SNP effects in the 3' untranslated region of the IL22RA2 risk locus in multiple sclerosis.

Recent large-scale association studies have identified over 100 MS risk loci. One of these MS risk variants is single-nucleotide polymorphism (SNP) rs17066096, located ~14 kb downstream of IL22RA2. IL22RA2 represents a compelling MS candidate gene due to the role of IL-22 in autoimmunity; however, rs17066096 does not map into any known functional element. We assessed whether rs17066096 or a nearby proxy SNP may exert pathogenic effects by affecting microRNA-to-mRNA binding and thus IL22RA2 expression using comprehensive in silico predictions, in vitro reporter assays, and genotyping experiments in 6,722 individuals. In silico screening identified two predicted microRNA binding sites in the 3'UTR of IL22RA2 (for hsa-miR-2278 and hsa-miR-411-5p) encompassing a SNP (rs28366) in moderate linkage disequilibrium with rs17066096 (r (2) = 0.4). The binding of both microRNAs to the IL22RA2 3'UTR was confirmed in vitro, but their binding affinities were not significantly affected by rs28366. Association analyses revealed significant association of rs17066096 and MS risk in our independent German dataset (odds ratio = 1.15, P = 3.48 × 10(-4)), but did not indicate rs28366 to be the cause of this signal. While our study provides independent validation of the association between rs17066096 and MS risk, this signal does not appear to be caused by sequence variants affecting microRNA function.

MANBA, CXCR5, SOX8, RPS6KB1 and ZBTB46 are genetic risk loci for multiple sclerosis.

A recent genome-wide association study reported five loci for which there was strong, but sub-genome-wide significant evidence for association with multiple sclerosis risk. The aim of this study was to evaluate the role of these potential risk loci in a large and independent data set of ≈ 20,000 subjects. We tested five single nucleotide polymorphisms rs228614 (MANBA), rs630923 (CXCR5), rs2744148 (SOX8), rs180515 (RPS6KB1), and rs6062314 (ZBTB46) for association with multiple sclerosis risk in a total of 8499 cases with multiple sclerosis, 8765 unrelated control subjects and 958 trios of European descent. In addition, we assessed the overall evidence for association by combining these newly generated data with the results from the original genome-wide association study by meta-analysis. All five tested single nucleotide polymorphisms showed consistent and statistically significant evidence for association with multiple sclerosis in our validation data sets (rs228614: odds ratio = 0.91, P = 2.4 × 10(-6); rs630923: odds ratio = 0.89, P = 1.2 × 10(-4); rs2744148: odds ratio = 1.14, P = 1.8 × 10(-6); rs180515: odds ratio = 1.12, P = 5.2 × 10(-7); rs6062314: odds ratio = 0.90, P = 4.3 × 10(-3)). Combining our data with results from the previous genome-wide association study by meta-analysis, the evidence for association was strengthened further, surpassing the threshold for genome-wide significance (P < 5 × 10(-8)) in each case. Our study provides compelling evidence that these five loci are genuine multiple sclerosis susceptibility loci. These results may eventually lead to a better understanding of the underlying disease pathophysiology.

Closing the case of APOE in multiple sclerosis: no association with disease risk in over 29 000 subjects.

BACKGROUND: Single nucleotide polymorphisms (SNPs) rs429358 (ε4) and rs7412 (ε2), both invoking changes in the amino-acid sequence of the apolipoprotein E (APOE) gene, have previously been tested for association with multiple sclerosis (MS) risk. However, none of these studies was sufficiently powered to detect modest effect sizes at acceptable type-I error rates. As both SNPs are only imperfectly captured on commonly used microarray genotyping platforms, their evaluation in the context of genome-wide association studies has been hindered until recently. METHODS: We genotyped 12 740 subjects hitherto not studied for their APOE status, imputed raw genotype data from 8739 subjects from five independent genome-wide association studies datasets using the most recent high-resolution reference panels, and extracted genotype data for 8265 subjects from previous candidate gene assessments. RESULTS: Despite sufficient power to detect associations at genome-wide significance thresholds across a range of ORs, our analyses did not support a role of rs429358 or rs7412 on MS susceptibility. This included meta-analyses of the combined data across 13 913 MS cases and 15 831 controls (OR=0.95, p=0.259, and OR 1.07, p=0.0569, for rs429358 and rs7412, respectively). CONCLUSION: Given the large sample size of our analyses, it is unlikely that the two APOE missense SNPs studied here exert any relevant effects on MS susceptibility.

Independent replication of STAT3 association with multiple sclerosis risk in a large German case-control sample.

Recent genome-wide association studies have implicated the "signal transducer and activator of transcription 3" gene (STAT3) as a putative new multiple sclerosis (MS) susceptibility locus. However, independent validation studies are sparse. Therefore, we performed a genetic association study of two STAT3 polymorphisms (rs744166 and rs2293152) in a large and independent German case-control sample of 5,904 subjects. We observed a nominally significant, albeit weak association between rs744166 and MS susceptibility (odds ratio = 1.09, P = 0.012) in our sample. This study supports the association between STAT3 and an increase in MS risk. Taking into account the functional role of STAT3, our results favour an involvement of T(h)17 lymphocytes in MS.

Psychological impact of genetic counseling for hereditary nonpolyposis colorectal cancer: the role of cancer history, gender, age, and psychological distress.

AIMS: We prospectively examined the impact of an initial interdisciplinary genetic counseling (human geneticist, oncologist, and psycho-oncologist) on feelings of anxiety with a special focus on subgroups related to personal cancer history, gender, age, and education. RESULTS: At baseline, cancer-affected men revealed a significantly higher level of anxiety than unaffected men (p<0.05), whereas history of cancer did not play a role in women. Furthermore, a significant interaction between time, gender, and age was identified for change of anxiety. While women in general and men above 50 years revealed a significant reduction in anxiety, younger men did not show any change over time. A logistic regression indicated that clinical Hospital Anxiety and Depression Scale-A cases can be predicted by general distress (Brief Symptom Inventory) as well as by hereditary nonpolyposis colorectal cancer-related cognitions of intrusion and avoidance (impact of event scale) with a correct classification of 86%. CONCLUSIONS: Although initial hereditary nonpolyposis colorectal cancer counseling leads to an overall reduction of anxiety, differential effects of cancer history, gender, and age focus on subgroups of cancer-affected men, who may display unexpectedly high anxiety scores at baseline. Especially younger men do not seem to reduce this high anxiety level. Baseline anxiety was mainly determined by maladaptive situation-specific cognitions. Therefore, consulters should be more aware of anxiety-related cognitions in cancer-affected younger men.

Three novel mutations in the ACTA2 gene in German patients with thoracic aortic aneurysms and dissections.

Mutations in the gene encoding smooth muscle cell alpha actin (ACTA2) have recently been shown to cause familial thoracic aortic aneurysms leading to type A dissections (TAAD) and predispose to premature stroke and coronary artery disease. In order to further explore the role of ACTA2 variations in the pathogenesis of TAAD, we sequenced the coding regions of this gene in 40 unrelated German patients with TAAD (with (n=21) or without (n=19) clinical features suggestive of Marfan syndrome). All patients had previously tested negative for mutations in the FBN1 and TGFBR2 genes. We identified three novel ACTA2 mutations and mapped them on a three-dimensional model of actin. Two mutations affect residues within (M49V) or adjacent to (R39C), the DNAse-I-binding loop within subdomain 2 of alpha actin. They were observed in families with recurrent aortic aneurysm (R39C) or aortic dissection (M49V). The third mutation causes an exchange in the vicinity of the ATP-binding site (G304R) in a patient thought to have isolated TAAD. None of the affected individuals had clinical features typical for Marfan syndrome, and no case of premature stroke or coronary artery disease was reported from the affected families. In conclusion, we underscore the role of ACTA2 mutations in nonsyndromic TAAD and suggest that ACTA2 should be included in the genes routinely investigated for syndromic and nonsyndromic TAAD. Detailed clinical investigations of additional families are warranted to further explore the full range of phenotypic signs associated with the three novel mutations described here.

Generalized progressive retinal atrophy in the Irish Glen of Imaal Terrier is associated with a deletion in the ADAM9 gene.

Generalized progressive retinal atrophy (gPRA) belongs to a group of inherited retinal diseases which are associated with gradual vision loss in various dog breeds, including the Irish Glen of Imaal Terrier (GIT). By genome-wide homozygosity mapping using SNP arrays and fine mapping of candidate regions, we assigned the gPRA candidate locus in this breed to canine chromosome 16. The respective region is syntenic with human chromosome 8 comprising the ADAM metallopeptidase domain 9 (ADAM9) gene. ADAM9 represents a strong candidate gene for canine retinal disease because mutations have previously been shown to cause autosomal recessively inherited human cone-rod dystrophy, a retinal disorder affecting photoreceptor function. Sequence analysis of ADAM9 in affected and carrier GITs revealed a deletion of exons 15 and 16 which alters the reading frame leading to a premature stop codon. This mutation was absent from 34 other dog breeds. A variable and, at times, very late onset of gPRA was confirmed in GITs by a relatively mild retinal degeneration at an advanced age. Hence, the identification of the genetic defect underlying gPRA in the GIT represents a suitable model for cone-rod dystrophy of humans, with superior potential to elucidate functional consequences of the recently described null mutations in the human ADAM9 gene.

Genetic variations in genes encoding RANK, RANKL, and OPG in rheumatoid arthritis: a case-control study.

OBJECTIVE: Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of the joints, which may lead to structural damage of the cartilage and bone. The receptor activator of nuclear factor-kappaB (RANK) and the osteoprotegerin (OPG) cascade system have been reported to be essential in osteoclastogenesis. Genetic variations in the genes coding for RANK, RANK ligand (RANKL), and OPG are thought to play roles in the susceptibility to RA. METHODS: In our case-control study, genomic DNA was obtained from 534 patients with RA who fulfilled the American College of Rheumatology 1987 criteria and 516 healthy control blood donors (HC). We studied 7 single-nucleotide polymorphisms (SNP) in the genes of RANK (2 SNP: rs1805034, rs35211496), OPG (2 SNP: rs3102735, rs2073618), and RANKL (3 SNP: rs9533156, rs2277438, rs1054016) using TaqMan assay-guided polymerase chain reaction. Genotype and allelic frequencies comparing RA patients with HC were analyzed by chi-square test for 2 x 3 and 2 x 2 tables, respectively. RESULTS: Genotype distributions of the SNP rs35211496 in the RANK gene as well as the SNP rs2277438 in the RANKL gene differed significantly between patients with RA and HC. The frequency of the minor allele of rs9533156 of RANKL was significantly higher in patients with RA than in HC (OR 0.84, 95% CI 0.71-0.99, p = 0.047). Multivariate analysis adjusted to sex and investigating SNP demonstrated a significantly elevated risk for RA associated with the major allele in the RANK SNP rs35211496 (p = 0.0231) and with the minor allele in the RANKL SNP rs2277438 (p = 0.0092). No significantly increased risk was detected in the other SNP. CONCLUSION: The minor allele of the RANK SNP rs35211496 may be protective against RA, while the minor alleles of the RANKL SNP rs2277438 may increase susceptibility to RA.

Contrasting association of a non-synonymous leptin receptor gene polymorphism with Wegener's granulomatosis and Churg-Strauss syndrome.

OBJECTIVE: There is evidence that the leptin/ghrelin system is involved in T-cell regulation and plays a role in (auto)immune disorders such as SLE, RA and ANCA-associated vasculitides (AAVs). Here, we evaluate the genetic background of this system in WG. METHODS: We screened variations in the genes encoding leptin, ghrelin and their receptors, the leptin receptor (LEPR) and the growth hormone secretagogue receptor (GHSR). Three single nucleotide polymorphisms (SNPs) in each gene region were analysed in 460 German WG cases and 878 ethnically matched healthy controls. RESULTS: A three-SNP haplotype of GHSR was significantly associated with WG [P = 0.0067; corrected P-value (P(c)) = 0.026; odds ratio (OR) = 1.30; 95% CI 1.08, 1.57], as was one non-synonymous SNP in LEPR (Lys656Asn, P = 0.0034; P(c) = 0.013; OR = 0.72; 95% CI 0.58, 0.90). These four SNPs were re-analysed in independent cohorts of 226 German WG cases and 519 controls. While the GHSR association was not confirmed, allele frequencies of the LEPR SNP were virtually identical to those from the initial cohorts. Analysis of this SNP in the combined WG and control panels revealed a significant association of the LEPR 656Lys allele with WG (P = 0.00032; P(c) = 0.0013; OR = 0.72; 95% CI 0.60, 0.86). Remarkably, the Lys656Asn SNP showed contrasting allele distribution in two cohorts of 108 and 88 German cases diagnosed with Churg-Strauss syndrome (CSS, combined P = 0.0067; OR = 1.41; 95% CI 1.10, 1.81), whereas identical allele frequencies were revealed when comparing British WG and microscopic polyangiitis cases. CONCLUSIONS: While GHSR has to be further evaluated, these data provide profound evidence for an association of the LEPR Lys656Asn SNP with AAV, resulting in opposing effects in WG and CSS.

Lifespan, lifetime reproductive performance and paternity loss of within-pair and extra-pair offspring in the coal tit Periparus ater.

The hypothesis that females of socially monogamous species obtain indirect benefits (good or compatible genes) from extra-pair mating behaviour has received enormous attention but much less generally accepted support. Here we ask whether selection for adult survival and fecundity or sexual selection contribute to indirect selection of the extra-pair mating behaviour in socially monogamous coal tits (Periparus ater). We tracked locally recruited individuals with known paternity status through their lives predicting that the extra-pair offspring (EPO) would outperform the within-pair offspring (WPO). No differences between the WPO and EPO recruits were detected in lifespan or age of first reproduction. However, the male WPO had a higher lifetime number of broods and higher lifetime number of social offspring compared with male EPO recruits, while no such differences were evident for female recruits. Male EPO recruits did not compensate for their lower social reproductive success by higher fertilization success within their social pair bonds. Thus, our results do not support the idea that enhanced adult survival, fecundity or within-pair fertilization success are manifestations of the genetic benefits of extra-pair matings. But we emphasize that a crucial fitness component, the extra-pair fertilization success of male recruits, has yet

Autosomal dominant hereditary spastic paraplegia: novel mutations in the REEP1 gene (SPG31).

BACKGROUND: Mutations in the SPG4 gene (spastin) and in the SPG3A gene (atlastin) account for the majority of 'pure' autosomal dominant form of hereditary spastic paraplegia (HSP). Recently, mutations in the REEP1 gene were identified to cause autosomal dominant HSP type SPG31. The purpose of this study was to determine the prevalence of REEP1 mutations in a cohort of 162 unrelated Caucasian index patients with 'pure' HSP and a positive family history (at least two persons per family presented symptoms). METHODS: 162 patients were screened for mutations by, both, DHPLC and direct sequencing. RESULTS: Ten mutations were identified in the REEP1 gene, these included eight novel mutations comprising small insertions/deletions causing frame shifts and subsequently premature stop codons, one nonsense mutation and one splice site mutation as well as two missense mutations. Both missense mutations and the splice site mutation were not identified in 170 control subjects. CONCLUSION: In our HSP cohort we found pathogenic mutations in 4.3% of cases with autosomal dominant inheritance. Our results confirm the previously observed mutation range of 3% to 6.5%, respectively, and they widen the spectrum of REEP1 mutations.