Visceral organ involvement and extracellular matrix changes in β2-microglobulin amyloidosis – a comparative study with systemic AA and AL amyloidosis

 Patterns of amyloid distribution and extracellular matrix changes in the heart and gastrointestinal tract were compared among β₂-microglobulin (B2M), AA (secondary), and AL (primary and multiple myeloma-associated) amyloidosis cases. B2M amyloid was found to be mainly distributed in the small arterioles, venules, endocardium and muscularis propria of these organs, the deposits characteristically forming subendothelial nodular lesions in the vessels. A marked increase of chondroitin sulfate (CS) was consistently detected in B2M amyloid. Heparan sulfate (HS) also showed an increase in amyloid deposits, but with less reactivity than CS in the small arterioles or venules. Basement membrane structures stained positively for laminin and collagen type IV were replaced by negative amyloid deposits. In the AL cases, the muscularis propria of the gastrointestinal tract was involved in amyloid deposits, as seen for the B2M type, but the vascular amyloid deposits were localized in the media and adventitia of larger vessels. Immunoreactivity for HS was more intense than that for CS, and no increase in laminin or collagen type IV was observed. In the AA cases, amyloid deposits were distributed in the capillaries, small arterioles, interstitium of the myocardium and mucosa. Immunoreactivity for laminin and collagen type IV was marked, and more intense than that for HS and CS. Although the existence of a direct relationship between increase in extracellular matrix material and amyloidogenesis remains to be proven, the observed variation in extracellular matrix changes in the background of each type of amyloidosis may indicate different binding sites of the amyloid precursor proteins, resulting in the specific histological features and distribution. Received: 23 August 1996 / Accepted: 9 January 1997     

The first case of familial Mediterranean fever associated with renal amyloidosis in Korea

Familial Mediterranean fever (FMF) is an auto-inflammatory disease characterized by periodic episodes of fever and recurrent polyserositis. It is caused by a dysfunction of pyrin (or marenostrin) as a result of a mutation within the MEFV gene. It occurs mostly in individuals of Mediterranean origin; however, it has also been reported in non-Mediterranean populations. In this report, we describe the first case of FMF in a Korean child. As eight-year-old boy presented recurrent febrile attacks from an unknown cause, an acute scrotum and renal amyloidosis. He also showed splenomegaly, lymphadenopathy, pleural effusion, ascites and elevated acute phase reactants. After MEFV gene analysis, he was diagnosed as FMF combined with amyloidosis.     

Inherited deleterious variants in GALNT12 are associated with CRC susceptibility

A recent report detailed the occurrence of both somatic and constitutional variants in the GALNT12 gene, located at 9q22.33, in some colorectal cancer (CRC) patients. In this study, we investigate the occurrence of inherited deleterious variants in GALNT12 in 118 families referred to a cancer genetics clinic. We discovered two deleterious variants (c.907G>A (p.Asp303Asn); c.1187A>G (p.Tyr396Cys)) in 4/118 probands. The variants, which were not found in 149 control individuals (P = 0.0376), cosegregate with CRC and/or adenomatous polyps in other family members. The probability by chance that cosegregation of c.907G>A with CRC and/or adenomatous polyps occurred, in the two pedigrees combined, was 1.56%. Although this study does not provide irrefutable evidence that GALNT12 variants are highly penetrant alleles that predispose to CRC in the majority of unexplained hereditary CRC families, it does provide additional evidence to support an important role of these variants in a proportion of this considerable high-risk group.     

Demonstration of amyloid A (AA) protein and amyloid P component (AP) in deposits of systemic amyloidosis associated with renal adenocarcinoma

The fibril protein in three cases of systemic amyloidosis associated with renal adenocarcinoma was identified as amyloid A protein (AA) using immunohistochemical staining techniques. Amyloid P component was also present in all deposits. In one case unfixed snap frozen tissues were studied directly whilst in the other two, which were investigated retrospectively, fixed paraffin sections were stained by immuno-fluorescence and immunoperoxidase methods after treatment with trypsin. Enzymatic digestion was necessary to restore reactivity with anti-AP but anti-AA reacted well without any such treatment. These findings establish that renal carcinoma, the carcinoma most frequently associated with systemic amyloidosis, causes the same type of secondary or reactive systemic amyloid as chronic infections and inflammatory disorders.     

Genome-wide screen for systemic lupus erythematosus susceptibility genes in multiplex families

Systemic lupus erythematosus (SLE) is the prototype of human autoimmune diseases. Its genetic component has been suggested by familial aggregation (lambdas = 20) and twin studies. We have screened the human genome to localize genetic intervals that may contain lupus susceptibility loci in a sample of 188 lupus patients belonging to 80 lupus families with two or more affected relatives per family using the ABI Prism linkage mapping set which includes 350 polymorphic markers with an average spacing of 12 cM. Non-parametric multipoint linkage analysis suggests evidence for predisposing loci on chromosomes 1 and 18. However, no single locus with overwhelming evidence for linkage was found, suggesting that there are no 'major' susceptibility genes segregating in families with SLE, and that the genetic etiology is more likely to result from the action of several genes of moderate effect. Furthermore, the support for a gene in the 1q44 region as well as in the 1p36 region is clearly found only in the Mexican American families with SLE but not in families of Caucasian ethnicity, suggesting that consideration of each ethnic group separately is crucial.     

Allelic variants in the PHTF1-PTPN22, C12orf30 and CD226 regions as candidate susceptibility factors for the type 1 diabetes in the Estonian population

Background  

Type 1 diabetes is a multifactorial disease with a strong genetic component. The aim of the study was to assess the impact of single nucleotide polymorphisms (SNPs) in several genes as susceptible markers in the risk of type 1 diabetes in the Estonian population. Methods: The rs6679677 (1p13), rs17696736 (12q24) and rs763361 (18q22) were genotyped in a total of 230 controls and 154 type 1 diabetes patients of Estonian origin.     

Evaluation of common genetic variants in 82 candidate genes as risk factors for neural tube defects

ABSTRACT: BACKGROUND: Neural tube defects (NTDs) are common birth defects (~1 in 1000 pregnancies in the US and Europe) that have complex origins, including environmental and genetic factors. A low level of maternal folate is one well-established risk factor, with maternal periconceptional folic acid supplementation reducing the occurrence of NTD pregnancies by 50-70%. Gene variants in the folate metabolic pathway (e.g., MTHFR rs1801133 (677 C > T) and MTHFD1 rs2236225 (R653Q)) have been found to increase NTD risk. We hypothesized that variants in additional folate/B12 pathway genes contribute to NTD risk. METHODS: A tagSNP approach was used to screen common variation in 82 candidate genes selected from the folate/B12 pathway and NTD mouse models. We initially genotyped polymorphisms in 320 Irish triads (NTD cases and their parents), including 301 cases and 341 Irish controls to perform case-control and family based association tests. Significantly associated polymorphisms were genotyped in a secondary set of 250 families that included 229 cases and 658 controls. The combined results for 1441 SNPs were used in a joint analysis to test for case and maternal effects. RESULTS: Nearly 70 SNPs in 30 genes were found to be associated with NTDs at the p < 0.01 level. The ten strongest association signals (p-value range: 0.0003-0.0023) were found in nine genes (MFTC, CDKN2A, ADA, PEMT, CUBN, GART, DNMT3A, MTHFD1 and T (Brachyury)) and included the known NTD risk factor MTHFD1 R653Q (rs2236225). The single strongest signal was observed in a new candidate, MFTC rs17803441 (OR = 1.61 [1.23-2.08], p = 0.0003 for the minor allele). Though nominally significant, these associations did not remain significant after correction for multiple hypothesis testing. CONCLUSIONS: To our knowledge, with respect to sample size and scope of evaluation of candidate polymorphisms, this is the largest NTD genetic association study reported to date. The scale of the study and the stringency of correction are likely to have contributed to real associations failing to survive correction. We have produced a ranked list of variants with the strongest association signals. Variants in the highest rank of associations are likely to include true associations and should be high priority candidates for further study of NTD risk.     

Classical and alternative pathway complement activation are not required for reactive systemic AA amyloid deposition in mice

During induction of reactive systemic amyloid A protein (AA) amyloidosis in mice, either by chronic inflammation or by severe acute inflammation following injection of amyloid enhancing factor, the earliest deposits form in a perifollicular distribution in the spleen. Because the splenic follicular localization of immune complexes and of the scrapie agent are both complement dependent in mice, we investigated the possible complement dependence of AA amyloid deposition. In preliminary experiments, substantial depletion of circulating C3 by cobra venom factor had little effect on experimental amyloid deposition. More importantly, mice with targeted deletion of the genes for C1q or for both factor B and C2, and therefore unable to sustain activation, respectively, of either the classical complement pathway or both the classical and alternative pathways, showed amyloid deposition similar to wild type controls. Complement activation by either the classical or alternative pathways is thus not apparently necessary for the experimental induction of systemic AA amyloid in mice.     

Genetic variations in innate immunity genes affect response to Coxiella burnetii and are associated with susceptibility to chronic Q fever

ObjectivesChronic Q fever is a persistent infection, mostly of aortic aneurysms, vascular prostheses or damaged heart valves, caused by the intracellular bacterium Coxiella burnetii. Only a fraction of C. burnetii-infected individuals at risk develop chronic Q fever. In these individuals, a defective innate immune response may contribute to the development of chronic Q fever. We assessed whether genetic variations in genes involved in the killing machinery for C. burnetii by macrophages, contribute to the progression to chronic Q fever.MethodsThe prevalence of 66 single nucleotide polymorphisms (SNPs) in 31 genes pivotal in phagolysosomal maturation, bacterial killing and autophagy, was determined in 173 chronic Q fever patients and 184 controls with risk factors for chronic Q fever and serological evidence of a C. burnetii infection. Associations were detected with univariate logistic regression models. To assess the effect of these SNPs on innate responses to C. burnetii, the C. burnetii-induced cytokine production and basal reactive oxygen species production of healthy volunteers was determined.ResultsRAB7A (rs13081864) and P2RX7 loss-of-function SNP (rs3751143) were more common in chronic Q fever patients than in controls. RAB5A (rs8682), P2RX7 gain-of-function SNP (rs1718119), MAP1LC3A (rs1040747) and ATG5 (rs2245214) were more common in controls. In healthy volunteers, RAB7A (rs13081864) and MAP1LC3A (rs1040747) influenced the C. burnetii-induced cytokine production. RAB7A (rs13081864) modulated basal reactive oxygen species production.ConclusionsRAB7A (rs13081864) and P2RX7 (rs3751143) are associated with the development of chronic Q fever, whereas RAB5A (rs8682), P2RX7 (rs1718119), MAP1LC3A (rs1040747) and ATG5 (rs2245214) may have protective effects.     

Genetic variants in apoptosis‐related genes associated with colorectal hyperplasia

Deregulation of apoptosis is a frequent alteration in early benign lesions of the colon mucosa and is thought to be a major contributor to tumor progression and cancer. Single nucleotide polymorphisms (SNPs) within apoptosis‐related genes could affect apoptotic responses and their identification might provide a basis to assess individual risk for development of early lesions. To investigate a possible association between genetic polymorphisms and the occurrence of hyperplastic polyps (HP), we developed a custom DNA chip assay for 1,536 SNPs in the coding and flanking regions of 826 genes with known functional roles in apoptosis or apoptosis‐associated (e.g., stress‐related) pathways. During a first round of screening, genotypes were determined for 272 endoscopy patients harboring hyperplastic colorectal polyps and for 512 sex and aged‐matched controls. A set of 14 candidate SNPs associated with HP (P < 0.01) was then evaluated in an independent cohort of patients (n = 38) and controls (n = 38). Following meta‐analysis of Stages I and II, a false discovery rate approach was applied. Among the 14 candidate SNPs, eight showed significant association (combined P < 0.01) with the occurrence of HP. The SNPs rs4709583 (PARK2) and rs10476823 (HDAC3) were analyzed for potential functional effects on RNA splicing and RNA half‐life. Despite its location near a splice site, alternative splicing was not detected for rs4709583 (PARK3). By contrast, cDNA analysis revealed use of a cryptic polyadenylation signal in the 3′UTR of HDAC3 mRNA and a longer mRNA half‐life in a cell line heterozygous for rs10476823. © 2014 Wiley Periodicals, Inc.     

Two transthyretin variants (TTR Ala-49 and TTR Gln-89) in two Sicilian kindreds with hereditary amyloidosis.

We report the biochemical and molecular characterization of two new transthyretin (TTR) variants in two Italian families with hereditary amyloidosis. Both families presented neuropathy and cardiomyopathy but they differ in other clinical features. These TTR variants were previously detected by isoelectric focusing (IEF); one is a neutral TTR variant and the other one is basic. By protein and DNA analysis the neutral variant was found to have a substitution of an alanine for a threonine residue at position 49 (TTR Ala-49) of the polypeptide chain. The basic variant has a glutamine residue replacing glutamate at position 89 (TTR Gln-89).     

Cumulative association of eight susceptibility genes with systemic lupus erythematosus in a Japanese female population

Although large-scale studies established many susceptibility genes to systemic lupus erythematosus (SLE), effect of each gene is not sufficiently large to be used alone to identify individuals with strong genetic predisposition. In this study, we analyzed the cumulative number of risk alleles at eight established susceptibility loci, HLA-DRB1, IRF5, STAT4, BLK, TNFAIP3, TNIP1, FCGR2B and TNFSF13, in 282 Japanese female SLE and 222 healthy female controls. The average number of risk alleles was significantly increased in SLE (8.07±1.60) than healthy controls (7.02±1.64) (P=1.63 × 10(-12)). Significant gene-gene interaction was not detected. When the subjects carrying seven risk alleles were used as a reference, the odds ratio (OR) for individuals carrying 10 and 11-13 risk alleles were 4.17 (95% confidence interval (CI) 1.89-9.19, P=0.0002) and 8.77 (95% CI 1.92-40.0, P=0.0016), respectively. In contrast, subjects with ≤4 risk alleles were significantly decreased in SLE (OR 0.15, CI 0.03-0.67, P=0.007). The proportion of the patients with neurologic disorder was significantly increased in those carrying ≥10 risk alleles than those with <10 (OR 2.30, CI 1.09-4.83, P=0.025). This study suggested that the cumulative number of risk alleles may efficiently distinguish groups with high and low genetic predisposition to SLE and its severe manifestation.     

FYB gene polymorphisms are associated with susceptibility for systemic lupus erythemathosus (SLE)

Systemic Lupus Erythematosus (SLE) is a multifactorial autoimmune disease affecting different organs or systems. Several genes have been associated with SLE susceptibility so far. A previous study has reported, in SLE patients, a differential expression of Fyn Binding Protein gene (FYB), encoding for a protein participating in the T cells signaling cascade and in the interleukin-2A expression modulation.     

Single suture craniosynostosis: Identification of rare variants in genes associated with syndromic forms

We report RNA‐Sequencing results on a cohort of patients with single suture craniosynostosis and demonstrate significant enrichment of heterozygous, rare, and damaging variants among key craniosynostosis‐related genes. Genetic burden analysis identified a significant increase in damaging variants in ATR, EFNA4, ERF, MEGF8, SCARF2, and TGFBR2. Of 391 participants, 15% were found to have damaging and potentially causal variants in 29 genes. We observed transmission in 96% of the affected individuals, and thus penetrance, epigenetics, and oligogenic factors need to be considered when recommending genetic testing in patients with nonsyndromic craniosynostosis.

     

Enrichment of pathogenic variants in genes associated with inborn errors of metabolism in psychiatric populations

Many genetic conditions can mimic mental health disorders, with psychiatric symptoms that are difficult to treat with standard psychotropic medications. This study tests the hypothesis that psychiatric populations are enriched for pathogenic variants associated with selected inborn errors of metabolism (IEMs). Using next‐generation sequencing, 2046 psychiatric patients were screened for pathogenic variants in genes associated with four IEMs, Niemann‐Pick disease type C (NPC), Wilson disease (WD), homocystinuria (HOM), and acute intermittent porphyria (AIP). Among the 2046 cases, carrier rates of 0.83, 0.98, and 0.20%, for NPC, WD and HOM, and affected rates of 0.10 and 0.24% for NPC and AIP were seen, respectively. An enrichment of known and predicted pathogenic variants in the genes associated with NPC and AIP was found in the psychiatric cohort and especially in schizophrenia patients. The results of this study support that pathogenic variants in genes associated with IEMs are enriched in psychiatric populations. Underlying undiagnosed IEMs could account for the psychiatric symptomatology in a subset of psychiatric patients. Further studies are warranted to investigate the possibility that carriers for IEMs may have an increased risk for psychiatric disorders, particularly in the context of poor treatment response.