Project description:Mutations in the fibrinogen A alpha-chain gene are the most common cause of hereditary renal amyloidosis in the United Kingdom. Previous reports of fibrinogen A alpha-chain amyloidosis have been in isolated kindreds, usually in the context of a novel amyloidogenic mutation. Here, we describe 71 patients with fibrinogen amyloidosis, who were prospectively studied at the UK National Amyloidosis Centre. Median age at presentation was 58 yr, and renal involvement led to diagnosis in all cases. Even after a median follow-up of 4 yr, clinically significant extra-renal disease was rare. Renal histology was characteristic: striking glomerular enlargement with almost complete obliteration of the normal architecture by amyloid deposition and little or no vascular or interstitial amyloid. We discovered four amyloidogenic mutations in fibrinogen (P552H, E540V, T538K, and T525fs). A family history of renal disease was frequently absent. Median time from presentation to ESRD was 4.6 yr, and the estimated median patient survival from presentation was 15.2 yr. Among 44 patients who reached ESRD, median survival was 9.3 yr. Twelve renal transplants survived for a median of 6.0 (0-12.2) yr. Seven grafts had failed after median follow up from transplantation of 5.8 yr, including three from recurrent amyloid after 5.8, 6.0, and 7.4 yr; three grafts failed immediately for surgical reasons and one failed from transplant glomerulopathy after 5.8 yr with no histological evidence of amyloid. At censor, the longest surviving graft was 12.2 yr. In summary, fibrinogen amyloidosis is predominantly a renal disease characterized by variable penetrance, distinctive histological appearance, proteinuria, and progressive renal impairment. Survival is markedly better than observed with systemic AL amyloidosis, and outcomes with renal replacement therapy are comparable to those for age-matched individuals with nondiabetic renal disease.
Project description:Introduction: Systemic amyloidosis is a diverse group of diseases that, although rare, pose a serious health issue and can lead to organ failure and death. Amyloid typing is essential in determining the causative protein and initiating proper treatment. Mass spectrometry-based proteomics is currently the most sensitive and accurate means of typing amyloid. Areas covered: Amyloidosis can be systemic or localized, acquired or hereditary, and can affect any organ or tissue. Diagnosis requires biopsy, histological analysis, and typing of the causative protein to determine treatment. The kidneys are the most commonly affected organ in systemic disease. Fibrinogen alpha chain amyloidosis (AFib) is the most prevalent form of hereditary renal amyloidosis. Select mutations in the fibrinogen Aα (FGA) gene lead to AFib. Expert commentary: Mass spectrometry is currently the most specific and sensitive method for amyloid typing. Identification of the mutated fibrinogen alpha chain can be difficult in the case of 'private' frameshift mutations, which dramatically change the sequences of the expressed fibrinogen alpha chain. A combination of expert pathologist review, mass spectrometry, and gene sequencing can allow for confident diagnosis and determination of the fibrinogen alpha chain mutated sequence.
Project description:Systemic hereditary amyloidoses are autosomal dominant diseases associated with mutations in genes encoding ten different proteins. The clinical phenotype has implications on therapeutic approach, but it is commonly variable and largely dependent on the type of mutation. Except for rare cases involving gelsolin or transthyretin, patients are heterozygous for the amyloidogenic variants. Here we describe the first patient identified worldwide as homozygous for a nephropathic amyloidosis, involving the fibrinogen variant associated with the fibrinogen alpha-chain E526V (p.Glu545Val) mutation. In 1989, a 44-year-old woman presented with hypertension, hepatosplenomegaly, nephrotic syndrome, and renal failure. She started hemodialysis in 1990 and 6 years later underwent isolated kidney transplantation from a deceased donor. Graft function and clinical status were unremarkable for 16 years, despite progressively increased left ventricular mass on echocardiography. In 2012, 4 months before death, she deteriorated rapidly with severe heart failure, precipitated by Clostridium difficile colitis and urosepsis. Affected family members developed nephropathy, on average, nearly three decades later, which may be explained by the gene dosage effects on the phenotype of E526V (p.Glu545Val) fibrinogen A alpha-chain amyloidosis.
Project description:BackgroundDue to inconsistencies with reported myofibrillar myopathy (MFM), including autosomal dominant inheritance, late onset and a slowly progressive course, the severe, recessively inherited form of CRYAB (alpha-B crystallin) gene-related infantile MFM has been suggested. Here, we report an infant in a Chinese family with fatal neonatal-onset hypertonic MFM with a novel CRYAB homozygous variant (c.3G > A (p.Met1?)).MethodsMuscle biopsy indicated that muscle fibers showed a uniformly small diameter, cell atrophy, and visible focal muscle fiber degeneration and necrosis consistent with myogenic myopathy. We performed the whole exome sequencing of pathogenic genes and identified it as MFM.ResultsThe proband presented with profound muscle stiffness, progressive respiratory distress and a concurrent abnormal increase in myocardial enzymogram, and the patient died in the 17th month of life. Muscle biopsy and electron microscopy results were consistent with ultramicroscopic myogenic damage and pathological changes. Mutation analysis of the proband identified a novel rare homozygous mutation in the initiation codon of the CRYAB gene, which was inherited from currently asymptomatic, heterozygous carrier parents, and his heterozygous biological brother is unaffected.ConclusionsThis article reports one infant with CRYAB-related neonatal onset MFM with a novel homozygous variant in CRYAB. To our knowledge, this is the first reported case of infantile alpha-Bcrystallinopathy in the Chinese population.
Project description:IntroductionHereditary fibrinogen Aα-chain (AFib) amyloidosis is a relatively uncommon renal disease associated with a small number of pathogenic fibrinogen Aα (FibA) variants; wild-type FibA normally does not result in amyloid deposition. Proteomics is now routinely used to identify the amyloid type in clinical samples, and we report here our algorithm for identification of FibA in amyloid.MethodsProteomics data from 1001 Congo red-positive patient samples were examined using the Mascot search engine to interrogate the Swiss-Prot database and generate protein identity scores. An algorithm was applied to identify FibA as the amyloid protein based on Mascot scores. FibA variants were identified by appending the known amyloidogenic variant sequences to the Swiss-Prot database.ResultsAFib amyloid was identified by proteomics in 64 renal samples based on the Mascot scores relative to other amyloid proteins, the presence of a pathogenic variant, and coverage of the p.449-621 sequence. Contamination by blood could be excluded from a comparison of the FibA score with that of the fibrinogen β and γ chains. The proteomics results were consistent with the clinical diagnosis. Four additional renal samples did not fulfill all the criteria using the algorithm but were adjudged as AFib amyloid based on a full assessment of the clinical and biochemical results.ConclusionAFib amyloid can be identified reliably in glomerular amyloid by proteomics using a score-based algorithm. Proteomics data should be used as a guide to AFib diagnosis, with the results considered together with all available clinical and laboratory information.
Project description:BackgroundCongenital hypofibrinogenemia is a rare bleeding disease that is classified as the quantitative deficient type. In the present study, investigated the relationship between the genotype and phenotype in a family with hypofibrinogenemia.MethodsThe proband was aware of a predisposition to bleeding. Functional analysis was performed for her all family members, including coagulation function tests, thrombus molecular markers, thromboelastography, scanning electron microscopy, DNA sequencing, and high-performance liquid chromatography-mass spectrometry (HPLC-MS). Pathogenicity analysis and protein modeling of mutant amino acids were also performed.ResultsA novel heterozygous mutation in c.1094delG was detected in FGG exon 8, which resulted in p. Cys365Phefs*41 (containing the signal peptide) in the proband and her mother, who showed a corresponding decrease in fibrinogen function and levels. Thromboelastography indicated that the strength of their blood clots decreased and they had an increased risk of bleeding. The proband fibrin network structure was looser than healthy controls, with large pores in the network, which increased the permeability of lytic enzymes. Results of HPLC-MS showed a lack of mutant peptide chain expression in their plasma, indicating that the family had congenital hypofibrinogenemia, with a clinical phenotype that is related to the degree of fibrinogen deficiency. The mutation truncated the γ-peptide chain and destroyed the functional structure of fibrinogen, including the γ352Cys-γ365Cys disulfide bond. The truncated peptide chains may also lead to nonsense-mediated decay.ConclusionsThe mutation induced a structural change at the carboxyl-terminal of the fibrinogen molecule, leading to fibrinogen secretion dysfunction.
Project description:There are no reports on the relationship between familial medullary thyroid carcinoma (FMTC) associated with cutaneous amyloidosis (CA) and RET or OSMR/IL31RA gene mutations. In this study, we investigated a Chinese family with FMTC/CA and found a recurrent RET c.2671T>G (p.S891A) mutation in six of 17 family members. Three of the six p.S891A mutation carriers presented with medullary thyroid carcinoma (MTC). Of them, three (two with and one without MTC) were diagnosed as having combined lichen/macular biphasic CA. We also identified a novel RET variant, c.1573C>T (p.R525W) in five members. Of them, three carriers had no evidence of thyroid/skin or basal serum/stimulated calcitonin abnormalities. In vitro cell proliferation assay indicated that oncogenic activity of RET p.S891A was slightly enhanced by p.R525W, whereas p.R525W alone had no effect on cell proliferation. Meanwhile, we identified a novel OSMR variant, c.1538G>A (p.G513D) in seven members. We noticed that three OSMR p.G513D carriers presenting with CA also had the RET p.S891A mutation. Our investigation indicated that the RET p.S891A mutation combined with OSMR p.G513D may underlie a novel phenotype manifesting as FMTC and CA.
Project description:Light chain (AL) amyloidosis is the most common form of amyloidosis involving the kidney. It is characterized by albuminuria, progressing to overt nephrotic syndrome and eventually end-stage renal failure if diagnosed late or ineffectively treated, and in most cases by concomitant heart involvement. Cardiac amyloidosis is the main determinant of survival, whereas the risk of dialysis is predicted by baseline proteinuria and glomerular filtration rate, and by response to therapy. The backbone of treatment is chemotherapy targeting the underlying plasma cell clone, that needs to be risk-adapted due to the frailty of patients with AL amyloidosis who have cardiac and/or multiorgan involvement. Low-risk patients (?20%) can be considered for autologous stem cell transplantation that can be preceded by induction and/or followed by consolidation with bortezomib-based regimens. Bortezomib combined with alkylators, such as melphalan, preferred in patients harboring t(11;14), or cyclophosphamide, is used in most intermediate-risk patients, and with cautious dose escalation in high-risk subjects. Novel, powerful anti-plasma cell agents, such as pomalidomide, ixazomib, and daratumumab, prove effective in the relapsed/refractory setting, and are being moved to upfront therapy in clinical trials. Novel approaches based on small molecules interfering with the amyloidogenic process and on antibodies targeting the amyloid deposits gave promising results in preliminary uncontrolled studies, are being tested in controlled trials, and will likely prove powerful complements to chemotherapy. Finally, improvements in the understanding of the molecular mechanisms of organ damage are unveiling novel potential treatment targets, moving toward a cure for this dreadful disease.
Project description:ObjectiveTo investigate a novel insertion variant of CRYGD identified in a Chinese family with nuclear congenital cataract.MethodsA Chinese family with congenital nuclear cataract was recruited for the mutational screening of candidate genes by direct sequencing. Recombinant N-terminal Myc tagged wildtype or mutant CRYGD was expressed in HEK293T cells. The expression pattern, protein solubility and subcellular distribution were analyzed by western blotting and immunofluorescence.Principal findingsA novel insertion variant, c.451_452insGACT, in CRYGD was identified in the patients. It causes a frameshift and a premature termination of the polypeptide to become Y151*. A significantly reduced solubility was observed for this mutant. Unlike wildtype CRYGD, which existed mainly in the cytoplasm, Y151* was mis-located in the nucleus.ConclusionsWe have identified a novel mutation, c.451_452insGACT, in CRYGD, which is associated with nuclear cataract. This is the first insertion mutation of CRYGD found to cause autosomal dominant congenital cataract. The mutant protein, with loss of solubility and localization to the nucleus, is hypothesized to be the major cause of cataract in these patients.
Project description:BackgroundAmyloid light chain (AL) amyloidosis is the most common systemic amyloidosis. The objective of this scoping review was to map the available literature on the diagnosis of AL amyloidosis in China.Materials and methodsThe published academic papers related to the diagnosis of AL amyloidosis were screened from 1 January 2000 to 15 September 2021. Chinese patients who have suspected AL amyloidosis were included. The included studies were categorized into accuracy studies and descriptive studies based on if the studies supplied the diagnostic accuracy data or not. The information on the diagnostic methods reported by included studies was synthesized.ResultsForty-three articles were included for the final scoping review, with 31 belonging to descriptive studies and 12 having information on diagnostic accuracy. Although cardiac involvement was second top in Chinese patients with AL amyloidosis, a cardiac biopsy was rare. Next, we found light chain classification and monoclonal (M-) protein identification were essential methods for the diagnosis of AL amyloidosis in China. In addition, some combined tests (e.g. immunohistochemistry and serum free light chain, immunohistochemistry and immunofixation electrophoresis, and serum free light chain and immunofixation electrophoresis) can increase the sensitivity of the diagnosis. Finally, several adjuvant methods (e.g. Imaging, N-terminal-pro hormone BNP, and brain natriuretic peptide test) were important for AL amyloidosis diagnosis.ConclusionThis scoping review details the characteristics and results of the recently published studies on diagnosing AL Amyloidosis in China. Biopsy is the most important method for AL Amyloidosis diagnosis in China. In addition, combined tests and some adjuvant methods played essential roles in the diagnosis. Further research is required to determine an acceptable and feasible diagnostic algorithm after symptom onset. REGISTRATION: INPLASY2022100096KEY MESSAGESThis scoping review details the characteristics and results of the recently published studies on diagnosing Amyloid light chain (AL) Amyloidosis in China.Biopsy is the most important method for AL Amyloidosis diagnosis in China.Combined tests and some adjuvant methods played essential roles in the diagnosis.