Familial Amyloidotic Cardiomyopathy Research Articles

Preparative Scale Production of Recombinant Human Transthyretin for Biophysical Studies of Protein-Ligand and Protein-Protein Interactions.

Human transthyretin (hTTR), a serum protein with a main role in transporting thyroid hormones and retinol through binding to the retinol-binding protein, is an amyloidogenic protein involved in familial amyloidotic polyneuropathy (FAP), familial amyloidotic cardiomyopathy, and central nervous system selective amyloidosis. hTTR also has a neuroprotective role in Alzheimer disease, being the major Aβ binding protein in human cerebrospinal fluid (CSF) that prevents amyloid-β (Aβ) aggregation with consequent abrogation of toxicity. Here we report an optimized preparative expression and purification protocol of hTTR (wt and amyloidogenic mutants) for in vitro screening assays of TTR ligands acting as amyloidogenesis inhibitors or acting as molecular chaperones to enhance the TTR:Aβ interaction. Preparative yields were up to 660 mg of homogenous protein per L of culture in fed-batch bioreactor. The recombinant wt protein is mainly unmodified at Cys10, the single cysteine in the protein sequence, whereas the highly amyloidogenic Y78F variant renders mainly the S-glutathionated form, which has essentially the same amyloidogenic behavior than the reduced protein with free Cys10. The TTR production protocol has shown inter-batch reproducibility of expression and protein quality for in vitro screening assays.

Phenotypic profile of Ile68Leu transthyretin amyloidosis: an underdiagnosed cause of heart failure.

Cardiac amyloidosis remains a great challenge for the cardiologist. One of the three main aetiological forms, transthyretin-related hereditary amyloidosis (ATTRm), can present with several phenotypes, depending mainly on the specific mutation. We aimed to characterize the phenotype of patients with ATTRm due to Ile68Leu mutation, comparing them to patients with wild-type transthyretin amyloidosis (ATTRwt). Data of 67 Ile68Leu ATTRm patients from two Italian referral centres (Bologna and Florence) were retrospectively analysed and compared to those of 82 ATTRwt patients. Fifty-five unaffected mutation carriers were also analysed. Cumulative disease onset was 50% at age 71. A total of 56/67 (84%) patients had a predominantly cardiac phenotype at presentation with concentric increase in left ventricular wall thickness [median 17 mm], and normal or near normal left ventricular ejection fraction (79% of patients). Low QRS voltages were present only in 29% of patients but voltage/mass ratio was low (0.5). Carpal tunnel syndrome was noted in 43%. The overall phenotypic profile was similar to ATTRwt but Ile68Leu ATTRm patients typically presented younger (median 71 vs. 78 years) and were more likely to have (mild) symptomatic neurological involvement (19% vs. 2%). Male prevalence was 44% in unaffected mutation carriers and 78% in affected patients. Age-adjusted survival was comparable between groups. Ile68Leu ATTRm is a cause of familial amyloidotic cardiomyopathy endemic in central-northern Italy and presents as hypertrophic/restrictive cardiomyopathy quite similar to ATTRwt. Male preponderance is present in affected patients but not in unaffected mutation carriers. Age-adjusted survival is similar to ATTRwt.

Population diversity of the genetically determined TTR expression in human tissues and its implications in TTR amyloidosis

BackgroundTransthyretin (TTR) amyloidosis is a hereditary disease with a complex genotype-phenotype correlation. We conducted a literature survey to define the clinical landscape of TTR amyloidosis across populations worldwide. Then, we investigated whether the genetically determined TTR expression differs among human populations, contributing to the differences observed in patients. Polygenic scores for genetically determined TTR expression in 14 clinically relevant tissues were constructed using data from the GTEx (Genotype-Tissue Expression) project and tested in the samples from the 1,000 Genomes Project.ResultsWe observed differences among the ancestral groups and, to a lesser extent, among the investigated populations within the ancestry groups. Scandinavian populations differed in their genetically determined TTR expression of skeletal muscle tissue with respect to Southern Europeans (p = 6.79*10−6). This is in line with epidemiological data related to Swedish and Portuguese TTR Val30Met endemic areas. Familial amyloidotic cardiomyopathy (TTR deposits occur primarily in heart tissues) presents clinical variability among human populations, a finding that agrees with the among-ancestry diversity of genetically determined TTR expression in heart tissues (i.e., Atrial Appendage p = 4.55*10−28; Left Ventricle p = 6.54*10−35).ConclusionsGenetically determined TTR expression varied across human populations. This might contribute to the genotype-phenotype correlation of TTR amyloidosis.

Analysis of disease progression in patients with transthyretin cardiac amyloidosis

Background In transthyretin (TTR) cardiac amyloidosis, myocardial deposition of liver-derived TTR fibrils results in heart failure and death. Wild-type TTR (ATTRwt) amyloidosis is an acquired disease, whereas familial amyloidotic cardiomyopathy (FAC) is a hereditary form of the disease caused by mutations in the TTR gene resulting in the deposition of both mutant and wild-type TTR. Published data on disease progression in TTR cardiac amyloidosis is limited. To explore this further, we analyzed natural history data in ATTRwt amyloidosis patients to characterize disease progression in this population and compared this to our previously reported data in FAC.

The flavonoid luteolin, but not luteolin-7-O-glucoside, prevents a transthyretin mediated toxic response.

Transthyretin (TTR) is a homotetrameric plasma protein with amyloidogenic properties that has been linked to the development of familial amyloidotic polyneuropathy (FAP), familial amyloidotic cardiomyopathy, and senile systemic amyloidosis. The in vivo role of TTR is associated with transport of thyroxine hormone T4 and retinol-binding protein. Loss of the tetrameric integrity of TTR is a rate-limiting step in the process of TTR amyloid formation, and ligands with the ability to bind within the thyroxin binding site (TBS) can stabilize the tetramer, a feature that is currently used as a therapeutic approach for FAP. Several different flavonoids have recently been identified that impair amyloid formation. The flavonoid luteolin shows therapeutic potential with low incidence of unwanted side effects. In this work, we show that luteolin effectively attenuates the cytotoxic response to TTR in cultured neuronal cells and rescues the phenotype of a Drosophila melanogaster model of FAP. The plant-derived luteolin analogue cynaroside has a glucoside group in position 7 of the flavone A-ring and as opposed to luteolin is unable to stabilize TTR tetramers and thus prevents a cytotoxic effect. We generated high-resolution crystal-structures of both TTR wild type and the amyloidogenic mutant V30M in complex with luteolin. The results show that the A-ring of luteolin, in contrast to what was previously suggested, is buried within the TBS, consequently explaining the lack of activity from cynaroside. The flavonoids represent an interesting group of drug candidates for TTR amyloidosis. The present investigation shows the potential of luteolin as a stabilizer of TTR in vivo. We also show an alternative orientation of luteolin within the TBS which could represent a general mode of binding of flavonoids to TTR and is of importance concerning the future design of tetramer stabilizing drugs.

A PHASE 2, MULTI-CENTER, OPEN-LABEL TRIAL TO EVALUATE THE SAFETY, PHARMACOKINETICS, PHARMACODYNAMICS AND EXPLORATORY CLINICAL ACTIVITY OF ALN-TTRSC, AN RNAI THERAPEUTIC FOR THE TREATMENT OF PATIENTS WITH TRANSTHYRETIN CARDIAC AMYLOIDOSIS

Transthyretin (TTR) cardiac amyloidosis is an under-recognized form of cardiomyopathy caused by the deposition of liver-derived mutant and/or wild-type (WT) TTR in the myocardium resulting in heart failure and death. The hereditary form, known as familial amyloidotic cardiomyopathy (FAC), is most

Phase 2, open-label extension (OLE) study of revusiran, an investigational RNAi therapeutic for the treatment of patients with transthyretin cardiac amyloidosis

Background In transthyretin (TTR) cardiac amyloidosis, myocardial deposition and accumulation of liver-derived TTR fibrils results in heart failure and death. The hereditary form of the disease is caused by mutations in the TTR gene and presents as familial amyloidotic cardiomyopathy (FAC), whereas senile systemic amyloidosis (SSA) is an acquired disease caused by wild-type TTR. There are currently no approved therapies available for ATTR cardiac amyloidosis. Revusiran is a liver-directed subcutaneously administered investigational RNA interference therapeutic comprised of a GalNAc-siRNA conjugate targeting both mutant and wild-type TTR mRNA. A Ph 2 study of revusiran in 26 patients with ATTR cardiac amyloidosis, in which revusiran was generally well tolerated and associated with > 85% sustained knockdown of serum TTR, was recently completed. A Ph 2 open label extension (OLE) of revusiran, available to all patients who participated in the Ph 2 trial, was initiated in November 2014.

Phase I First-in-Humans Trial of ALN-TTRsc, a Novel RNA Interference Therapeutic for the Treatment of Familial Amyloidotic Cardiomyopathy (FAC)

Transthyretin (TTR) cardiac amyloidosis is caused by the deposition of liver-derived mutant and/or wild-type TTR in the myocardium, leading to heart failure and death. The hereditary form, known as familial amyloidotic cardiomyopathy (FAC), is most frequently associated with the Val122Ile mutation in older African-American and Afro-Caribbean males and is estimated to affect at least 40,000 people worldwide. Treatment options are limited, and include medical management of heart failure symptoms, as well as heart transplantation in a small number of patients young enough to undergo this procedure.

Long‐term outcome in patients treated with combined heart and liver transplantation for familial amyloidotic cardiomyopathy

The amyloidogenic transthyretin (ATTR) mutation Leu111Met causes a primarily cardiac amyloidosis: Familial amyloidotic cardiomyopathy (FAC). Combined heart-liver transplantation (CHLTx) is the preferred treatment for patients with heart failure due to familial amyloidosis, but information on outcome of patients with Leu111Met mutation is limited. The aim of this study was to evaluate the long-term outcome of CHLTx in patients with FAC. Between 1998 and 2009, CHLTx was performed in 7 FAC patients (four men). Six patients underwent simultaneous transplantation. All patients suffered from severe cardiomyopathy. Mean recipient age at transplantation was 48.3 ± 4.2 yr. Mean follow-up was 55 months. No peroperative mortality occured. Two patients died within the first year (infection, multi-organ failure) of transplantation. Cumulative survival at 4.5 yr was 71%. No significant liver rejections occurred. One patient experienced an episode of cardiac rejection requiring treatment (H2R). For the surviving five patients, most recent left ventricular ejection fraction was 0.61 ± 0.02, and plasma creatinine was 129 ± 47 μM. None developed significant allograft vasculopathy or neuropathy after transplantation. No recurrence of cardiac amyloid was found. CHLTx in selected patients with FAC due to Leu111Met mutation offers acceptable long-term survival, almost comparable with isolated cardiac transplantation. Allograft rejection was rare.

Evaluation of tafamidis as first-line therapeutic agent for transthyretin familial amyloidotic polyneuropathy.

Almost 100 mutations in the human transthyretin (TTR) gene cause the autosomal dominant disorders of familial amyloidotic polyneuropathy (FAP) and familial amyloidotic cardiomyopathy. While these have been clinically classified as separate disorders, the peripheral and autonomic nervous systems and the heart are frequently involved in the same patient. Deposition of amyloid derived from a kinetically or thermodynamically unstable mutant TTR precursor produces an ascending sensorimotor polyneuropathy with marked autonomic involvement. Since 1990, treatment has been liver transplantation from a donor carrying two wild-type TTR genes, providing a crude form of gene therapy. Multiple studies have shown that small molecules fitting in the T4-binding pocket of TTR can stabilize the molecule, reducing its capacity to release the fibril precursor. Tafamidis is the first molecule to be tested in a placebo-controlled trial in patients with TTR-associated FAP. While the trial did not achieve its primary endpoints, it did stabilize TTR in vivo and had a favorable effect on some aspects of disease progression, particularly when administered early in the course. It may represent an alternative to liver transplantation, particularly in patients with early disease related to the V30M mutation. Longer-term studies are required to determine whether it represents a stabilizing or remittive form of treatment.

Methods to Evaluate the Inhibition of TTR Fibrillogenesis Induced by Small Ligands

Transthyretin is an amyloidogenic protein associated with several amyloidosis, namely familial amyloidotic polyneuropathy, familial amyloidotic cardiomyopathy, and central nervous system selective amyloidosis, familial rare diseases caused by single point mutants, and senile systemic amyloidosis associated with wild-type TTR. The current model for amyloid fibril formation involves initial dissociation of the native TTR tetramer into non-native monomers which associate into soluble oligomers and protofibrils that evolve to mature amyloid deposits. A number of efforts are addressed to identify small molecules targeting the formation, clearance, or assembly of toxic aggregates as a promising therapeutic strategy to treat amyloidosis. This review classifies and summarizes the different strategies and assays that have been developed in vitro, ex vivo, and in vivo as tools to screen libraries of compounds or to test compounds from rational design in the search of drug candidates for the treatment of TTR-associated amyloidosis. Depending on the property they measure, the assays are classified as: a) in vitro assays that monitor protein aggregation and/or fibril formation, b) in vitro assays that monitor binding to native protein, c) ex vivo TTR plasma selectivity assays, d) in vitro assays for tetrameric TTR stabilization, e) cellular assays, and f) animal models to evaluate amyloidosis inhibitors.

Transthyretin Cardiac Amyloidoses in Older North Americans

The amyloidoses are a group of hereditary or acquired disorders caused by the extracellular deposition of insoluble protein fibrils that impair tissue structure and function. All amyloidoses result from protein misfolding, a common mechanism for disorders in older persons, including Alzheimer's disease and Parkinson's disease. Abnormalities in the protein transthyretin (TTR), a serum transporter of thyroxine and retinol, is the most common cause of cardiac amyloidoses in elderly adults. Mutations in TTR can result in familial amyloidotic cardiomyopathy, and wild-type TTR can result in senile cardiac amyloidosis. These underdiagnosed disorders are much more common than previously thought. The resulting restrictive cardiomyopathy can cause congestive heart failure, arrhythmias, and advanced conduction system disease. Although historically difficult to make, the diagnosis of TTR cardiac amyloidosis has become easier in recent years with advances in cardiac imaging and more widespread use of genetic analysis. Although therapy has largely involved supportive medical care, avoidance of potentially toxic agents, and rarely organ transplantation, the near future brings the possibility of targeted pharmacotherapies designed to prevent TTR misfolding and amyloid deposition. Because these disease-modifying agents are designed to prevent disease progression, it has become increasingly important that older persons with TTR amyloidosis be expeditiously identified and considered for enrollment in clinical registries and trials.

532 Long-Term Outcome in Patients Treated with Combined Heart- and Liver Transplantation for Familial Amyloidotic Cardiomyopathy

Hereditary transthyretin (TTR) amyloidosis is a rare form of systemic amyloidosis caused by mutated TTR. Different amyloidogenic TTR (ATTR)-mutations are known to cause familial amyloidosis (FA). In Denmark the ATTR Leu111Met-mutation causes a primarily cardiac amyloidosis: Familial amyloidotic cardiomyopathy (FAC). Combined heart and liver transplantation (CHLTx) is considered the treatment of choice for patients with heart failure due to FA, but information on outcome of patients with Leu111Met-mutation is very limited.

The binding of 2,4-dinitrophenol to wild-type and amyloidogenic transthyretin

Systemic deposition of transthyretin (TTR) amyloid fibrils is always observed in familial amyloidotic polyneuropathy, senile systemic amyloidosis and familial amyloidotic cardiomyopathy patients. Destabilization of the molecule leads to a cascade of events which result in fibril formation. The destabilization of a native protein with consequent conformational changes appears to be a common link in several human amyloid diseases. Intensive research has been directed towards finding small molecules that could work as therapeutic agents for the prevention/inhibition of amyloid diseases through stabilization of the native fold of the potentially amyloidogenic protein. This work provides insight into the structural determinants of the highly stabilizing effects of 2,4-dinitrophenol on wild-type TTR. It is also shown that similar interactions are established between this molecule and two highly amyloidogenic TTR variants: TTR L55P and TTR Y78F. In the three crystal complexes, 2,4-dinitrophenol occupies the two hormone-binding sites of the TTR tetramer. As a result of 2,4-dinitrophenol binding, the two dimers in the TTR tetramer become closer, increasing the stability of the protein. The three-dimensional structures now determined allow a comprehensive description of key interactions between transthyretin and 2,4-dinitrophenol, a small compound that holds promise as a template for the design of a therapeutical drug for amyloid diseases.

Amyloidogenic and anti-amyloidogenic properties of recombinant transthyretin variants

Most transthyretin (TTR) mutations lead to TTR amyloid depositions in patients with familial amyloidotic polyneuropathy and familial amyloidotic cardiomyopathy. However, though an amyloidogenic protein itself, TTR inhibits aggregation of Alzheimer's amyloid beta protein (Aβ) in vitro and in vivo. The pathogenic relationship between two amyloidogenic processes remains unclear. To understand how TTR mutations influence the ability of TTR to inhibit Aβ amyloidosis, forty-seven recombinant TTR variants were produced and analyzed. We showed that all recombinant proteins formed tetramers and were functional in thyroxine binding. Acid denaturation at pH 3.8 resulted in aggregation and fibril formation of all TTR variants. However, only TTR G42 and TTR P55 formed fibrils at pH 6.8. Most TTR variants bound to Aβ and inhibited Aβ aggregation in vitro. TTR variants S64, A71, Q89, V107, H114 and I122 revealed decreased binding to Aβ and decreased inhibition of Aβ aggregation. Only TTR G42 and TTR P55 completely failed to bind Aβ and to inhibit Aβ aggregation. We suggest that TTR variants characterized by decreased binding to Aβ or by decreased inhibition of Aβ aggregation in vitro may contribute to Aβ amyloid formation in vivo. These TTR variants might be important targets for epidemiological studies in Alzheimer's disease.

The V122I cardiomyopathy variant of transthyretin increases the velocity of rate-limiting tetramer dissociation, resulting in accelerated amyloidosis.

The transthyretin (TTR) amyloid diseases are of keen interest, because there are >80 mutations that cause, and a few mutations that suppress, disease. The V122I variant is the most common amyloidogenic mutation worldwide, producing familial amyloidotic cardiomyopathy primarily in individuals of African descent. The substitution shifts the tetramer-folded monomer equilibrium toward monomer (lowers tetramer stability) and lowers the kinetic barrier associated with rate-limiting tetramer dissociation (pH 7; relative to wild-type TTR) required for amyloid fibril formation. Fibril formation is also accelerated because the folded monomer resulting from the tetramer-folded monomer equilibrium rapidly undergoes partial denaturation and self-assembles into amyloid (in vitro) when subjected to a mild denaturation stress (e.g., pH 4.8). Incorporation of the V122I mutation into a folded monomeric variant of transthyretin reveals that this mutation does not destabilize the tertiary structure or alter the rate of amyloidogenesis relative to the wild-type monomer. The increase in the velocity of rate-limiting tetramer dissociation coupled with the lowered tetramer stability (increasing the mol fraction of folded monomer present at equilibrium) may explain why V122I confers an apparent absolute anatomic risk for cardiac amyloid deposition.

Amyloid and Nonfibrillar Deposits in Mice Transgenic for Wild-Type Human Transthyretin: A Possible Model for Senile Systemic Amyloidosis

The human serum protein transthyretin (TTR) is highly fibrillogenic in vitro and is the fibril precursor in both autosomal dominant (familial amyloidotic polyneuropathy [FAP] and familial amyloidotic cardiomyopathy [FAC]) and sporadic (senile systemic amyloidosis [SSA]) forms of human cardiac amyloidosis. We have produced mouse strains transgenic for either wild-type or mutant (TTRLeu55Pro) human TTR genes. Eighty-four percent of C57Bl/6xDBA/2 mice older than 18 months, transgenic for the wild-type human TTR gene, develop TTR deposits that occur primarily in heart and kidney. In most of the animals, the deposits are nonfibrillar and non-Congophilic, but 20% of animals older than 18 months that bear the transgene have human TTR cardiac amyloid deposits identical to the lesions seen in SSA. Amino terminal amino acid sequence analysis and mass spectrometry of the major component extracted from amyloid and nonamyloid deposits revealed that both were intact human TTR monomers with no evidence of proteolysis or codeposition of murine TTR. This is the first instance in which the proteins from amyloid and nonfibrillar deposits in the same or syngeneic animals have been shown to be identical by sequence analysis. It is also the first time in any form of amyloidosis that nonfibrillar deposits have been shown to systematically occur temporally before the appearance of fibrils derived from the same precursor in the same tissues. These findings suggest, but do not prove, that the nonamyloid deposits represent a precursor of the fibril. The differences in the ultrastructure and binding properties of the deposits, despite the identical sizes and amino terminal amino acid sequences of the TTR and the dissociation of deposition and fibril formation, provide evidence that in vivo factors, perhaps associated with aging, impact on both systemic precursor deposition and amyloid fibril formation.

Structure of the Val122Ile variant transthyretin - a cardiomyopathic mutant.

The Val122Ile mutant transthyretin (TTR Ile122) is an amyloidogenic protein which has been described as the major protein component of amyloid fibrils isolated from patients with familial amyloidotic cardiomyopathy (FAC), a disease characterized by cardiac failure and amyloid deposits in the heart. The reasons for the deposition of TTR are still unknown and it is conceivable that a conformational alteration, resulting from the mutation, is fundamental for amyloid formation. The three-dimensional structure of TTR Ile122 was determined and refined to a crystallographic R factor of 15.8% at 1.9 A resolution. The r.m.s. deviation from ideality in bond distances is 0.019 A and in angle-bonded distances is 0.027 A. The presence of two crystallographically independent monomers in the asymmetric unit allowed additional means of estimation of atomic coordinate error. The structure of the mutant is essentially identical to that of the wild-type transthyretin (TTR). The largest deviations occur in surface loops and in the region of the substitution. The protein is a tetramer composed of identical subunits; each monomer has two four-stranded beta-sheets which are extended to eight-stranded beta-sheets when two monomers associate through hydrogen bonds forming a dimer, which is the crystallographic asymmetric unit. The replacement of valine for isoleucine introduces very small alterations in relation to the wild-type protein; nevertheless they seem to confirm a tendency for a less stable tetrameric structure. This would support the idea that the tetrameric structure might be disrupted in amyloid fibrils.

Transthyretin Ser6 as a neutral polymorphism in familial amyloidotic polyneuropathy

Over fifty transthyretin variants have been described, mostly in patients with familial amyloidoses (familial amyloidotic-polyneuropathy (FAP) and familial amyloidotic cardiomyopathy (FAC)). Other TTR variants, including TTR Ser6, have been found in screening studies of the “normal” population and, apparently, are non-pathogenic.The role of TTR mutations in amyloid formation is not yet fully understood and it is relevant to study individuals carrying two TTR variants, to examine the possible inter-action of such variants in amyloidogenesis.We previously reported that TTR Ser6 is a common polymorphism. To investigate whether this variant might have an effect on TTR amyloidogenicity and clinical disease expression, we have screened for TTR Ser6 in 85 patients carriers of TTR Met30 and 12 patients with senile systemic amyloidosis (SSA). Among the FAP patients, seven were found to be compound heterozygotes carrying also Ser6 on the other allele. No Ser6 allele was found in individuals with systemic senile amy...

Purification and Characterization of Amyloid-Related Transthyretin Associated with Familial Amyloidotic Cardiomyopathy

Analysis of amyloid fibril material associated with familial amyloidotic cardiomyopathy revealed that it contains a mixture of transthyretin-related polypeptides. The major protein band in SDS/polyacrylamide gel corresponding to a molecular mass of 14.5 kDa, consists of transthyretin fragments starting at positions 46, 49 and 59, the latter not previously identified, and one blocked fragment derived from the N-terminal part of transthyretin. In reverse-phase HPLC, the major fragment recovered was that starting at Thr49, indicating a trypsin-like cleavage (Lys at position 48). Two minor bands, corresponding to 17 kDa and 35 kDa, contained proteins with blocked N-termini, and migrated as monomeric and dimeric transthyretin, respectively. A 13-kDa protein band was found to contain transthyretin with a ragged N-terminus, mainly starting at positions 2 and 5. Three more bands, corresponding to 10, 25 and 29 kDa, consist of transthyretin molecules with blocked N-termini and most likely of aggregates of truncated molecules. A point mutation of amyloid transthyretin was identified at position 111 (Met instead of Leu in normal serum transthyretin) which confirms the mutation found for Danish siblings with familial amyloidotic cardiomyopathy. However, the presence of a non-variant amyloid transthyretin was also observed, indicating that the Danish kindred is heterozygous with respect to this point mutation. Isoelectric focusing of the amyloid fibril material resolved multiple protein bands ranging over pH 4.5-6.5, confirming heterogeneities. Methanol extraction of the cardiac amyloid fibril material prior to the purification steps reveals a methanol-soluble substance amounting to about 10% (by mass dry material) of the amyloid fibril material. A yellow substance in this fraction shows absorbance maxima (270, 280 and 430 nm) similar to those observed for transthyretin in normal serum. Gas chromatography/mass spectrometry of the methanol extract revealed the presence of saturated fatty acids (C14:0, C16:0 and C18:0 in the corresponding ratio 2:8:5) and polyunsaturated fatty acids (C16:1, C18:1, C18:2 and C20:4 in the corresponding ratio of 1:2:1:1) as further constituents of the amyloid fibril material.