Amyloid polyneuropathy with transthyretin Arg50 in a Japanese case from Osaka

Widespread Cardiac and Vasomotor Autonomic Dysfunction in Non-Val30Met Hereditary Transthyretin Amyloidosis

Objective The autonomic functions of hereditary transthyretin (ATTRm) amyloidosis, traditionally referred to as familial amyloid polyneuropathy, have primarily been investigated in patients with Val30Met mutations, and information regarding non-Val30Met patients is scarce. The aim of this study was to systematically investigate the cardiac and peripheral vasomotor autonomic functions in non-Val30Met patients. Methods The coefficient of variation of R-R intervals (CVR-R), responses to the Valsalva manoeuvre, head-up tilt test results, noradrenaline infusion test results, and the (123) I-metaiodobenzylguanidine (MIBG) uptake on myocardial scintigraphy were assessed in five patients. The predominant manifestations were neuropathy in three patients (Val94Gly, Val71Ala, and Pro24Ser), cardiomyopathy in one (Thr60Ala), and oculoleptomeningeal involvement in one (Tyr114Cys). Results Although one patient with predominant cardiomyopathy did not manifest orthostatic hypotension during the head-up tilt test, the CVR-R, responses to the Valsalva manoeuvre, and myocardial MIBG uptake indicated the presence of cardiac sympathetic and parasympathetic dysfunction in all patients. The total peripheral resistance at 60° tilt did not increase from the baseline values in any of the examined patients. An infusion of low-dose noradrenaline induced an increase in the systolic blood pressure, except in one patient with mild neuropathy. Conclusion Cardiac and peripheral vasomotor autonomic dysfunctions were prevalent in non-Val30Met patients, irrespective of their phenotype, suggesting a common pathology of autonomic involvement. However, the vasoconstrictor function was preserved, even in a patient with advanced neuropathy.

Survival After Transplantation in Patients With Mutations Other Than Val30Met: Extracts From the FAP World Transplant Registry

Background

Liver transplantation (LTx) has been performed for hereditary transthyretin amyloidosis (ATTR) since 1990. Outcomes for a relatively large series of LTx ATTR patients with the Val30Met (mutation are available, but for non-Val30Met patients, only a few reports with a small number of patients exist. Here, we present outcomes for non-Val30Met ATTR patients after LTx, as reported to the Familial Amyloid Polyneuropathy World Transplant Registry (FAPWTR).

Methods

Data regarding outcome were extracted for all non-Val30Met patients reported to the registry. Survival rates were analyzed by the Kaplan-Meier method and log-rank test.

Results

The total number of patients with a non-Val30Met mutation in the registry was 264 (174 men and 90 women), representing 57 mutations. The 10-year survival varied markedly for the 9 most common mutations, ranging from 21% for Ser50Arg to 85% for Val71Ala. Poor survival was noted for all mutations with leptomeningeal complications except for those with the Tyr114Cys mutation.

Conclusions

Large differences in survival were observed relative to different mutations and between mutations with similar phenotypes. Excellent survival was noted for mutations, such as Leu111Met, Val71Ala, and Leu58His. Patients with mutations other than Val30Met are not a homogeneous group, and the term non-Val30Met should be used with caution or avoided. Moreover, for several mutations, data are too limited to allow evaluation of the efficacy of LTx, and continuous international collaboration is important for obtaining treatment guidance.

Description of transthyretin S50A, S52P and G47A mutations in familial amyloidosis polyneuropathy

OBJECTIVE

To describe 58 subjects with rare TTR mutations, and to compare the different biomarkers between carriers and patients.

METHODS

TTR gene sequence test was performed in 15 suspicious subjects and in their direct family. All positive subjects undertook prospective evaluations in a period of 49 months.

RESULTS

Of 95 genetic tests performed, 58 (61%) were positive for TTR mutations, Ser50Arg mutation in 38 (65%), Ser52Pro in 15 (26%) and Gly47Ala in 5 (9%). Initial symptoms were neuropathic in 19 (73%), gastrointestinal in 6 (23%) and autonomic in 1 (4%).

CONCLUSIONS

The natural history of Ser50Arg, Ser52Pro and Gly47Ala TTR mutations is similar to the Val30Met mutation described in endemic areas. The small fiber assessments were the initial tests to show abnormalities in asymptomatic subjects.

Familial amyloidosis with polyneuropathy associated with TTR Ser50Arg mutation

BACKGROUND

The phenotypic heterogeneity of transthyretin amyloidosis (ATTR) familial polyneuropathy may be linked to the type of mutation and to the environmental factors. A gender difference in relation to the severity of the disease has been suspected. More than 100 different pathogenic variants of hereditary transthyretin (TTR) mutations have been reported.

OBJECTIVE

To describe 32 patients with confirmed TTR Ser50Arg mutation from the same geographical origin.

METHODS

Seven families with up to four affected generations underwent genetic testing and prospective clinical and laboratory evaluations.

RESULTS

The mutation was confirmed in seven patients from different families with clinical symptoms compatible with ATTR amyloidosis, and in 25 (62%) of the 40 direct relatives tested. Of the 32 patients with positive test results, 18 (56%) were men. Only 5 (16%) subjects were disease-free at the time of the genetic test (mean age: 20, range: 18-30-year-old). The rest developed symptoms at a young age, between ages 36 and 41. Symptomatic, histologically positive patients were older than carriers and symptomatic patients without a confirmatory biopsy. The later generation displayed symptoms at a younger age. Initial manifestations in the 27 symptomatic patients were neuropathic in 19 (70%), gastrointestinal in 6 (22%) and autonomic in 1 (4%). Significant differences were demonstrated among genders, where men had a considerably worse outcome.

CONCLUSION

ATTR Ser50Arg mutation was associated with an early onset, an unbalanced male to female ratio, a more aggressive course in males and possibly displayed anticipation.

A case of atypical amyloid polyneuropathy with predominant upper-limb involvement with the diagnosis unexpectedly found at lung operation

We present a patient of familial amyloid polyneuropathy (FAP) with predominant upper-limb involvement, the pattern of which resembled a mononeuropathy multiplex pattern. Sural nerve biopsy failed to diagnose the disorder, but lung partial resection performed later for other diagnostic purposes suggested FAP. A rare mutation in the transthyretin gene (S50R) was subsequently confirmed. Diagnostic challenges of FAP with atypical clinical presentations, including difficulties in pathological diagnosis, are discussed with a review of the literature.

Familial amyloid polyneuropathy associated with TTRSer50Arg mutation in two Iberian families presenting a novel single base change in the mutant gene

We present two families, from Spain and Portugal, with familial amyloid polyneuropathy (FAP) associated with the mutation TTRSer50Arg. This mutation was first described in two Japanese patients from independent families and later in a French-Italian patient and a Vietnamese family. The two families presented here, are the first to be diagnosed with this mutation in the Iberian Peninsula. In the patients of both families, FAP was very aggressive as they rapidly developed multiple symptoms with progressive deterioration; we emphasize the presence of severe orthostatic hypotension in the Spanish proband which confined him to a wheelchair. This proband was the first patient with this mutation to have undergone liver transplantation and results were encouraging. The mutation was detected in four patients and one disease-free relative by DNA sequencing of exon 3 and induced mutation restriction analysis. The most outstanding feature was the single base transversion A to C in codon 50 (CGT instead of AGT), whereas in both Japanese patients and the French-Italian patient it was T to G (AGG instead of AGT). To our knowledge only six FAP mutations with more than one single nucleotide mutation for the same codon have been reported to date.

Cardiac amyloidosis: heterogenous pathogenic backgrounds

Cardiac amyloidosis is a fatal disorder which develops on the basis of the different pathologic conditions in systemic amyloidosis: the most common underlying disease is immunoglobulin light chain-derived primary amyloidosis and the next is transthyretin-related hereditary amyloidosis; the latter disorder, typically represented by familial amyloid polyneuropathy, was long regarded as an endemic disease. However, this disorder has now been shown to involve a highly variable clinical picture due to a large number of transthyretin gene mutations, and many patients with diverse ancestors suffer from severe cardiac amyloidosis. Additionally, senile systemic amyloidosis is now noted as a cause of cardiac dysfunction in elderly individuals. Echocardiogram and myocardial technetium-99m-pyrophosphate scintigraphy can provide characteristic findings. Immunohistochemistry on tissue amyloid, biochemical analysis of serum and urine proteins, and DNA sequencing are usually employed to determine the disease-related amyloid fibril protein. Although systemic amyloidosis has become treatable, the prognosis of each patient who received up-to-date and effective, but nevertheless stressful, therapy depends on the severity of cardiac involvement by amyloid deposition.

Clinical and pathological studies of cardiac amyloidosis in transthyretin type familial amyloid polyneuropathy

To clarify the clinicopathological features of cardiac amyloidosis in transthyretin (TTR) familial amyloid polyneuropathy (FAP), 169 patients were divided into three groups. Group I consisted of 113 patients with ATTR Val30Met who originated from an endemic focus, II consisted of 36 patients with ATTR Val30Met in nonendemic areas, and III consisted of 20 patients who had non-Val30Met ATTRs with 15 different gene mutations. The median age of onset in Group I was 34 years. On our initial examination, only one 65-year-old female patient was found to be suffering from congestive heart failure. During the follow-up of 65 patients, 7 developed congestive heart failure, the average duration of their illness being 8.7 years. In Group II, the median age of onset was 53 years and 6 of the 36 patients were diagnosed as having cardiac amyloidosis in the course of this disease. In 20 autopsied patients with ATTR Val30Met, congestive heart failure was clinically seen in 6 of the 20 and all 6 showed considerably increased cardiac weight (500g or more). In Group III patients with non-Val30Met ATTRs, the median age of onset was 51.5 years and 14 of the 20 patients had cardiac amyloidosis with congestive heart failure on admission or soon after a definite diagnosis. Cardiac amyloidosis occurs in the classical form of FAP with ATTR Val30Met, especially in older patients, and is also a common clinical manifestation in FAP patients with non-Val30Met ATTRs. In the pathogenesis of cardiac amyloidosis in ATTR FAP, aging seems to play an important role.

Postmortem findings in two familial amyloidosis patients with transthyretin variant Asp38Ala

Postmortem findings in 2 familial amyloidosis patients with the transthyretin variant (ATTR), Asp38Ala, are described Both showed cardiac failure, and progressive peripheral and autonomic neuropathy and died at the ages 82 and 57, respectively. TTR immunoreactive amyloid deposition was observed to be extensive in the myocardium, peripheral nerves, sympathetic ganglia and gastrointestinal tract. The pulmonary parenchyma was also diffusely involved, but renal glomeruli, follicular tissues of the thyroid, and the leptomeninges and subarachnoidal vessels of the central nervous system showed little deposition. The latter findings are not usually seen in the patients with ATTR Val30Met, the most common form of familial amyloidosis. Additionally, the clinicopathological findings of familial amyloidosis with ATTR Asp38Ala seem to vary in the different individuals.

The evolution of gene expression, structure and function of transthyretin

Thyroxine, the most abundant thyroid hormone in blood, partitions into lipid membranes. In a network-like system, thyroxine-binding plasma proteins counteract this partitioning and establish intravascular, protein-bound thyroxine pools. These are far larger than the free thyroxine pools. In larger eutherians, proteins specifically binding thyroxine are albumin, transthyretin, and thyroxine-binding globulin. Some binding of thyroxine can also occur to lipoproteins. During evolution, transthyretin synthesis first appeared in the choroid plexus of the stem reptiles, about 300 million years ago. Transthretin synthesis in the liver evolved much later, independently, in birds, eutherians and some marsupial species. Analysis of 57 human transthyretin variants suggests that most mutations in transthyretin are not compatible with its normal metabolism and lead to its deposition as amyloid. Analysis of transthyretin or its gene in 20 different species shows that evolutionary changes of transthyretin predominantly occurred near the N-termini. A change in RNA splicing between exon 1 and exon 2 led to a decrease in hydrophobicity and length of the N-termini. It is proposed that the selection pressure producing these changes was the need for a more effective prevention of thyroxine partitioning into lipids. Lipid pools increased during evolution with the increases in relative sizes of brains and internal organs and changes in lipid composition of membranes in ectothermic and endothermic species.

Familial amyloid polyneuropathy associated with transthyretin Gly42 mutation: a quantitative light and electron microscopic study of the peripheral nervous system

We performed extensive quantitative analyses of the peripheral nervous system (PNS) of two siblings with familial amyloid polyneuropathy (FAP) caused by a transthyretin (TTR) Gly42 mutation. Pronounced amyloid deposition was found in the sympathetic ganglia (SyG), dorsal root ganglia (DRG) and throughout the length of the peripheral nerve fibers with some accumulation in the more proximal portion. There was severe neuronal loss in the SyG and DRG together with nerve fiber depletion in the nerve trunk, while only a small amount of amyloid deposition with mild fiber loss was seen in the spinal roots. Sprouts of regenerating axons were very scanty even in the spinal nerves or roots. A teased fiber study mainly showed demyelinating fibers, but axonal degeneration was also present throughout peripheral nerves. An electron microscopic study showed fine amyloid fibrils in direct contact with the axoplasmic membrane of demyelinated axons and destruction of axons in some areas. Amyloid deposition within the PINS in this type of FAP resembled that in type I FAP (TTR Met30). However, direct axonal damage by amyloid fibrils appeared to be more prominent in our cases than in type I FAP. Lectin histochemistry using Ulex europaeus agglutinin I demonstrated preferential depletion of small neurons in the DRG and their primary afferent fibers in the spinal dorsal horn. Primary axonal degeneration and ganglionopathy due to amyloid deposition appear to be the pathogenetic mechanisms for peripheral neuropathy in this type of FAP.

Genetic abnormalities and pathogenesis of familial amyloidotic polyneuropathy

Familial amyloidotic polyneuropathy (FAP) is an autosomal inherited disease, characterized by extracellular amyloid deposits and by peripheral neuropathy. Amyloid fibrils derived from most types of FAP consist of variant transthyretin (TTR) with single amino acid substitutions, and methionine 30 TTR is the most common variant TTR. TTR is mainly produced in the liver and the choroid plexus. Biochemical and molecular biological techniques have been revealing the amyloidogenicity of variant TTR in vitro and in vivo using the transgenic mouse as a model. It will be important for the development of effective therapy to find out the factors, other than variant TTR, which affect amyloid deposition and define the tissue specificity of amyloid.