Transthyretin amyloid deposits in lumbar spinal stenosis and assessment of signs of systemic amyloidosis.

BACKGROUND: Wild-type transthyretin (ATTRwt) amyloidosis is the most common systemic amyloidosis in Western countries and manifests mainly as progressive restrictive cardiomyopathy. OBJECTIVE: To study the prevalence of ATTR deposits in ligament tissue in patients undergoing surgery for lumbar spinal stenosis and to assess whether these deposits are associated with cardiac amyloidosis. MATERIALS AND METHODS: A total of 250 patients, aged 50-89 (57% women), none with known cardiovascular disease, were included. Ligaments were investigated microscopically for amyloid. ATTR type was determined by immunohistochemistry and fibril type by Western blot. The amount of amyloid was graded 0-4. All patients with grade 3-4 ATTR deposits were offered cardiac investigation including ECG, cardiac ultrasound, plasma NT-proBNP and cardiac magnetic resonance (CMR), including modern tissue characterization. RESULTS: Amyloid was identified in 221 of the samples (88.4%). ATTR appeared in 93 samples (37%) of whom 42 (17 women and 25 men) were graded 3-4; all had fibril type A (mixture of full-length TTR and fragmented TTR). Twenty-nine of 42 patients with grade 3-4 ATTR deposits accepted cardiovascular investigations; none of them had definite signs of cardiac amyloidosis, but five men had a history of carpal tunnel syndrome. CONCLUSIONS: The prevalence of ATTR deposits in ligamentum flavum in patients with lumbar spinal stenosis was high but not associated with manifest ATTR cardiac amyloidosis. However, the findings of fibril type A, the prevalence of previous carpal tunnel syndrome and ATTR amyloid in surrounding adipose and vascular tissue indicate that amyloid deposits in ligamentum flavum may be an early manifestation of systemic ATTR disease.

One mutation, two distinct disease variants: unravelling the impact of transthyretin amyloid fibril composition.

Although hereditary transthyretin (h-ATTR) amyloidosis is a monogenetic disease, a large variation in its phenotype has been observed. The common hypothesis of amyloid fibril formation involves dissociation of the transthyretin (TTR) tetramer into monomers that after misfolding reassemble into amyloid fibrils. This notion is partly challenged by the finding of two distinct types of amyloid fibrils. One of these, type A, consists of C-terminal ATTR fragments and full-length TTR, whereas the other, type B, consists only of full-length TTR. All organs of an individual patient contain ATTR deposits of either type A or type B fibrils, and the composition in each individual remains unchanged over time. The finding of two distinct types of ATTR fibrils suggests that there are at least two different pathways in operation for ATTR fibril formation. For the most common European mutation, TTR Val30Met, ATTR fibril composition is related to the outcome of liver transplantation, which is the first successful treatment for the disease, and the penetrance of the trait. In addition, the presence of C-terminal ATTR fragments has an impact on the affinity for various tracers used for noninvasive imaging of amyloid depositions such as 99 m-technetium-diphosphono-propanodicarboxylic acid scintigraphy and positron emission tomography utilizing Pittsburgh component B, and even for the gold standard diagnostic procedure, tissue biopsy stained by Congo red and examined under polarized light. The importance of amyloid fibril composition needs to be taken into consideration when designing clinical trials of treatment modalities, and also in the evaluation of diagnostic methods such as imaging techniques.

Mitochondrial haplogroup is associated with the phenotype of familial amyloidosis with polyneuropathy in Swedish and French patients.

Familial amyloidotic polyneuropathy (FAP) is a monogenic disease caused by mutations in the transthyretin (TTR) gene. The phenotype of the most common TTR mutation, V30M, varies within and between populations. Oxidative stress and protein misfolding are cellular processes involved in the development of FAP. Because the mitochondria are important for both these processes, we investigated if mitochondrial haplogroups are related to age at onset of the disease in Swedish and French FAP patients. Mitochondrial haplogroup analysis was performed on 25 early-onset (below 40 years) and 29 late-onset (above 51 years) Swedish FAP patients. DNA from 249 Swedish individuals served as controls. In addition, 6 early-onset and 17 late-onset French FAP patients were examined with 25 French controls. The haplogroup distribution among late-onset Swedish and French cases was similar to that found in the general populations, whereas among early-onset cases a different haplogroup distribution was seen. The relatively rare haplogroup K was significantly more common among early-onset cases. Our findings substantiate the suggestion that a genetic component, still to be found, affecting mitochondrial function has an impact on the amyloid generating process in transthyretin amyloidosis.

Do troponin and B-natriuretic peptide detect cardiomyopathy in transthyretin amyloidosis?

OBJECTIVES: Cardiomyopathy is a well known complication in familial amyloidotic polyneuropathy (FAP). Troponin T and B-natriuretic peptide (BNP) have been shown to be excellent markers for heart complications in AL-amyloidosis. The aim of the study was to investigate troponin T, troponin I and BNP as markers for myocardial damage and failure in FAP. DESIGN: Retrospective investigation of patients with FAP. SETTING: Tertiary referral centre. SUBJECTS: Twenty-nine patients who had been submitted for evaluation of FAP. INTERVENTIONS: Two-dimensional M-mode and Doppler echocardiography and strain echocardiographic examination. Measurement of Troponin T, troponin I and BNP. RESULTS: Troponin T was detectable in only three patients who all had abnormal interventricular septal (IVS) thickness. Troponin I was abnormal in six patients (21%), of which only two had an increased IVS thickness. The heart function was generally well preserved in the patients in spite of hypertrophy of the IVS in 14 patients. BNP was elevated in 22 patients (76%), and it correlated significantly with IVS thickness and basal septal strain. CONCLUSIONS: Transthyretin amyloid seems to be less harmful to myocytes than that of AL amyloid as evaluated by serum troponin T and I as well as by echocardiography. BNP appears to be a sensitive marker for cardiomyopathy in FAP, and could prove valuable for follow-up purposes as has been shown for AL-amyloidosis patients.

Impact of homozygosity for an amyloidogenic transthyretin mutation on phenotype and long term outcome.

Although amyloidogenic transthyretin (ATTR) mutations are common in several populations, such as black Americans, the small number of diagnosed patients homozygous for TTR amyloid and the short follow up in most studies has until now prevented an analysis of their phenotype. In Sweden, nine homozygous patients from eight families carrying the ATTR mutation Val30Met, which gives rise to fatal neuropathic amyloidosis (FAP), have been identified and have now been followed for up to 15 years. This has enabled an analysis of the phenotype of homozygous patients. Genetic testing and detection of amyloid deposits in the vitreous body or in intestinal or skin biopsies confirmed the diagnosis in all patients. The patients' symptoms were obtained from medical records. For comparison, we used a group of 35 heterozygous non-transplanted patients with FAP (18 men and 17 women), who had been evaluated at the Department of Medicine, Umeå University Hospital before their deaths. Vitreous amyloidosis was the most prevalent symptom in the homozygous group, and in two patients it was the only manifestation of the disease during their lifetime. The age at onset was not different from that of heterozygous patients, and their survival tended not to be shorter but actually longer than for heterozygotes. Homozygosity for the mutation associated with FAP, ATTR Val30Met, does not implicate a more severe phenotype for Swedish patients. The most common symptom was vitreous opacity, which may be the only manifestation of the disease. These findings point to the possibilities of different pathways for amyloid formation, or the presence of hitherto unknown genes operating in amyloid formation.

Enhancement of AA-amyloid formation in mice by transthyretin amyloid fragments and polyethylene glycol.

The mechanism behind amyloid formation is unknown in all types of amyloidosis. Several substances can enhance amyloid formation in animal experiments. To induce secondary systemic amyloid (AA-type amyloid) formation, we injected silver nitrate into mice together with either amyloid fibrils obtained from patients with familial polyneuropathy (FAP) type I or polyethylene glycol (PEG). Mice injected with silver nitrate only served as controls. Amyloid deposits were detectable at day 3 in animals injected with amyloid fibrils and in those injected with PEG, whereas in control mice, deposits were not noted before day 12. Our results indicate that amyloid fibrils from FAP patients and even a non-sulfate containing polysaccharide (PEG) have the potential to act as amyloid-enhancing factors.

Liver transplantation restores endocrine cells in patients with familial amyloidotic polyneuropathy.

BACKGROUND: The aim of this study was to investigate familial amyloidotic polyneuropathy, Portuguese type patients' endocrine cell content in the stomach and duodenum before and after liver transplantation, and to relate the findings to the patients' gastrointestinal disturbances. METHODS: Ten liver-transplanted familial amyloidotic polyneuropathy, Portuguese type patients and 10 healthy controls were seen. Endocrine cells were identified by immunohistochemistry and quantified with computerized image analysis. The activity of the cells was appraised by measurements of the cell secretory index and nuclear area. Clinical symptoms were obtained from the patients' medical records. RESULTS: After transplantation, a significant increase of several endocrine cell types were noted, and the pretransplant depletion of several types of endocrine cells disappeared. For no type of endocrine cell was any difference compared with controls noted after transplantation. There was no significant decrease of the amount of amyloid in the biopsies after liver transplantation. The patients' symptoms remained generally unchanged after transplantation, although a substantial time lapse between pretransplant evaluation and transplantation was present. CONCLUSIONS: Liver transplantation restores the endocrine cells in the upper part of the gastrointestinal tract. The restoration was not correlated with an improvement of the patients' symptoms. No decrease of the amyloid deposits was noted.

Impact of autonomic neuropathy on circulatory instability during liver transplantation for familial amyloidotic polyneuropathy.

BACKGROUND: Circulatory instability with severe hypotension frequently complicates liver transplantation in patients with familial amyloidotic polyneuropathy. Autonomic dysfunction is found early in the course of the disease by analysis of beat-to-beat heart rate variability (HRV). The aim of the present study was to investigate the impact of autonomic neuropathy on intraoperative circulatory instability during liver transplantation for familial amyloidotic polyneuropathy. METHODS: Twenty-two patients were evaluated at the Department of Medicine, Umea University Hospital, by spectral analysis of HRV and later received liver transplants at Huddinge University Hospital. The low-and high-frequency bands obtained by spectral analysis of HRV in the supine and upright positions, respectively, were used as representative of sympathetic and parasympathetic activity. Circulatory instability during transplantation was defined as a fall in systolic arterial blood pressure below 70 mmHg for more than 5 min during the preanhepatic phase. RESULTS: Both arrhythmia preventing spectral analysis of HRV and a sympathetic variability peak below 2.5 mHz2 were significantly more common among patients with intraoperative circulatory instability (P=0.03 and 0. 004, respectively). A diminished increase in pulse rate when tilting the patients from the supine to the upright position was also more pronounced among patients with circulatory instability (P<0.05). CONCLUSIONS: The majority of patients who will develop circulatory instability with a pronounced fall in arterial blood pressure can be identified by Poincare plots of R-R intervals and spectral analysis of HRV. A low sympathetic peak or arrhythmia precluding spectral analysis of HRV is significantly related to operative circulatory instability.

Liver transplantation in familial amyloidotic polyneuropathy. Follow-up of the first 20 Swedish patients.

Familial amyloidotic polyneuropathy (FAP) is an inherited fatal form of amyloidosis caused by mutant transthyretin. The disease is characterized by progressive peripheral and autonomic neuropathy. Most of the transthyretin is produced by the liver, and we have shown previously that the metabolic deficiency can be corrected by liver transplantation. In the present study, the clinical results from the first 20 patients who underwent liver transplantation for FAP in Sweden are evaluated. Three of the patients suffered from renal failure and underwent a simultaneous kidney transplantation. Fourteen of the 20 patients (70%) are alive 10-52 months after transplantation. The patients' nutritional status at the time of transplantation had a significant impact on mortality and morbidity (P < 0.007). Long-standing disease was another negative prognostic factor (P < 0.02). One year after transplantation, the nutritional status had improved (P < 0.02). Improvements were also noted in walking capacity and for gastrointestinal and urogenital symptoms. The results show that liver transplantation offers an effective means to treat patients with FAP. The procedure should preferably be performed before the nutritional status is poor and advanced organ dysfunction has developed.

Early liver transplantation is essential for familial amyloidotic polyneuropathy patients' quality of life.

Nineteen patients, who had undergone liver transplantation for familial amyloidotic polyneuropathy, had answered a quality of life questionnaire including 61 questions on somatic and mental symptoms, social aspects of life, confidence and satisfaction before, one year, and two years after transplantation. We found that patient satisfaction was generally good two years or more after the transplantation. Most of the patients were very or quite satisfied with the result. All of them had the drive to go on and felt hopeful about the future. However, on the second follow-up, 37% of the patients noted that they felt more insecure in their everyday life and there was a significant difference between the two assessments. The diarrhea score became worse between one and two years after the transplantation and was closely related to the duration of the gastrointestinal symptoms and to the duration of the disease before transplantation. The mental symptoms also increased significantly between the evaluations and this related to the severity of the somatic symptoms. Our conclusion is that liver transplantation should be performed before advanced somatic symptoms start to develop in order to improve the patients' chances of a good quality of life following liver transplantation.

Heart failure caused by a novel amyloidogenic mutation of the transthyretin gene: ATTR Ala45Ser.

Cardiac failure in transthyretin (TTR) amyloidosis patients has been shown to be caused by different mutations in the TTR gene. In the present case, a 73-year-old man from Northern Sweden was evaluated for heart failure. Amyloid deposits were found in subcutaneous fat and in intestinal biopsies. The presence of a variant form of TTR was detected in the plasma by electrospray ionisation mass spectrometry (ESI-MS). The mutation was located by single-strand conformation polymorphism (SSCP) analysis of the TTR gene where a band shift was seen in exon 2. Direct sequencing of exon 2 revealed a single base-pair substitution (G1724T). This transversion results in an amino acid substitution at codon 45, alanine to serine (ATTR Ala45Ser). Mass spectrometry analysis excluded that the variant is a polymorphism, since no similar shift in molecular weight has been present in more than 200 control samples. Congo red and immunostaining of duodenum biopsy specimens confirmed the presence of systemic ATTR amyloidosis, and clinical examination, including echocardiography, found evidence of a restrictive cardiomyopathy. He had 10 years previously been operated for a bilateral carpal tunnel syndrome, but otherwise no symptoms were present that could be attributed to his systemic amyloidosis. No axonal polyneuropathy was noted at nerve conduction studies. This novel mutation is the second amyloidogenic TTR mutation found in the Swedish population.

Endocrine cells in the upper gastrointestinal tract in relation to gastrointestinal dysfunction in patients with familial amyloidotic polyneuropathy.

Gastrointestinal (GI) dysfunction is a common complication of familial amyloidotic polyneuropathy (FAP). In previous reports, a decreased content of small and large intestinal endocrine cells has been found in patients with FAP and it has been suggested that this may contribute to the development of GI disturbances. The aim of the present study was to investigate the endocrine cell content in the stomach and duodenum of FAP patients, and to correlate the findings with gastric emptying. Fifteen patients with FAP were included in the study. Twenty-eight subjects with macroscopically and histologically normal mucosa were used as controls for endocrine cell contents and 14 healthy subjects for gastric scintigraphy. The endocrine cells were identified by immunohistochemistry and quantified with image analysis. Gastric emptying time was detected by scintigraphy and endoscopy. The number of chromogranin A-immunoreactive (IR) cells was reduced in all investigated parts of the GI tract except bulbus duodeni. Gastrin/CCK cell content was reduced in duodenum, but tended to be increased in antrum of the stomach (P = 0.07). Otherwise, the content of all other endocrine cells types in the upper GI tract was reduced compared with controls. A correlation with malnutrition was found for gastric inhibitory polypeptide and secretin cell content in bulbus duodeni. Gastric scintigraphy disclosed delayed gastric emptying of solid food, but the finding was not correlated to the decreased content of neuroendocrine cells. The severity of endocrine cell depletion was not correlated to duration of GI disturbances. The present study showed that the endocrine cells of the stomach are affected in FAP patients and that the abnormalities in the upper GI endocrine cells occur early during the course of the disease.

Liver transplantation in transthyretin familial amyloid polyneuropathy: first report from Argentina.

This is the first report from Argentina of liver transplantation in patients with transthyretin related familial amyloidotic polyneuropathy. The aims of the study were to analyze the clinical characteristics of this new focus and evaluate the postoperative complications and long term follow up. Five of ten patients evaluated underwent liver transplantation. During the waiting period the polyneuropathy disability score in each patient progressed one or two stages. Pretransplant modified body mass index was 723. The procedure was done with full size grafts in four cases and a split right graft in one. All patients presented postoperative complications related to disease: severe edema of the legs, recurrent choledochal lithiasis, postoperative hernia, necrotizing fasciitis and ischemic rectosigmoidal perforation. Assessment of three patients after 20 months of transplantation showed improvement in somatic and mental symptoms. No improvement was noted in cardiac denervation and gastric stasis. Liver transplantation is a rational therapeutic option for transthyretin familial amyloidotic polyneuropathy in Argentina and should be indicated in earlier stages of the symptomatic disease to reduce the postoperative morbidity and mortality. Family studies and follow up of asymptomatic carriers will define the epidemiological behavior in this country and facilitate early therapeutic intervention.

Gastrointestinal dysfunction in familial amyloidotic polyneuropathy (ATTR Val30Met)--comparison of Swedish and Japanese patients.

The aim of the present study was to compare the clinical symptoms of Swedish and Japanese patients with familial amyloidotic polyneuropathy (ATTR Val30Met), especially gastrointestinal disturbances, and to correlate the findings with survival. Seventy-three Swedish and 47 Japanese patients were available for the study. Thirty-two Swedish and 7 Japanese patients had undergone liver transplantation. The mean age at onset was 50 for Swedish and 35 for Japanese patients (P < 0.001; non-transplanted patients). Fifty-five percent of Japanese patients had gastrointestinal disturbances from onset, compared to 22% of Swedish patients (P < 0.05; whole population). The Swedish patients average survival after the onset was significantly longer than Japanese patients (P < 0.05; non-transplanted patients). An early onset of gastrointestinal symptoms was correlated to a decreased survival for Swedish, but not for Japanese patients. Age at onset was not correlated to survival neither for Swedish nor for Japanese patients. We conclude that the clinical expressions of familial amyloidotic polyneuropathy ATTR Val30Met are different in Swedish and Japanese patients. The survival after the onset was shorter for Japanese patients, who also had an earlier onset of gastrointestinal disturbances, especially diarrhea than Swedish patients.

Impact of age and amyloidosis on thiol conjugation of transthyretin in hereditary transthyretin amyloidosis.

Variant forms and post-translational modifications of transthyretin (TTR) can be identified by electrospray ionisation mass spectrometry (ESI-MS). The aim of the present study was to investigate thiol conjugation of transthyretin and it's relation to age and symptomatic amyloid disease in different populations of variant TTR carriers. Plasma samples from 70 individuals from Denmark, Argentina, Sweden and Japan, with 2 different TTR mutations were analysed. The percentage cysteine (Cys) conjugated wild and variant TTR were calculated from the corresponding peaks of the spectra, and multiple regression analysis was employed to disclose relationships between age, symptomatic amyloid disease and origin. Age, origin and presence of symptomatic disease, were found to be independent factors related to transthyretin conjugation. A higher percentage of conjugated to unconjugated TTR was disclosed in symptomatic, but not in asymptomatic carriers. In summary: Thiol conjugation of TTR is dependent on age and presence of symptomatic amyloid disease. Furthermore, it varies between different populations. Variant TTR is more susceptible to thiol conjugation than the wild type. Post-translational factors may be related to amyloid formation and/or toxicity.

Outcome of liver transplantation for transthyretin amyloidosis: follow-up of Japanese familial amyloidotic polyneuropathy patients.

Since 1990, liver transplantation for familial amyloidotic polyneuropathy (FAP) has been carried out world-wide, and the outcome of the procedure seems to be promising. FAP is inherited systemic disease caused by mutated transthyretin. The most common cause is the valine to methionine substitution at position 30 (Met30). We have developed a scoring system for FAP Met30 that takes into account a variety of clinical symptoms of the disease. Six patients with FAP Met30 underwent extensive examinations according to our scoring system before and after transplantation. All patients survived the procedure and are alive after transplantation. Improvements of sensory and autonomic disturbances were observed during the initial 12 months after the procedure only, thereafter the patients' status remained unchanged. Following transplantation, no improvement of motor function and visceral organ damage were observed, but the modified body mass index improved in four of six patients after the operation. These results suggest that liver transplantation of FAP patients stops the progress of the disease, and that minor improvements are noted in several patients after the procedure. However, transplantation should be performed early after the onset of the disease in order to preserve the patients' functional status.

Gastric emptying in hereditary transthyretin amyloidosis: the impact of autonomic neuropathy.

BACKGROUND: Gastrointestinal (GI) complications are common in hereditary transthyretin amyloidosis and an autonomic dysfunction has been considered to explain these symptoms. The aim of this study was to investigate the impact of autonomic neuropathy on gastric emptying in hereditary transthyretin amyloidosis and to relate these findings to nutritional status, GI symptoms, gender, and age at disease onset. METHODS: Gastric emptying was evaluated with gastric emptying scintigraphy. Spectral analysis of the heart rate variability and cardiovascular responses after tilt test were used to assess the autonomic function. The nutritional status was evaluated with the modified body mass index (s-albumine × BMI). KEY RESULTS: Gastric retention was found in about one-third of the patients. A weak correlation was found between the scintigraphic gastric emptying rate and both the sympathetic (rs = -0.397, P < 0.001) and parasympathetic function (rs = -0.282, P = 0.002). The gastric emptying rate was slower in those with lower or both upper and lower GI symptoms compared with those without symptoms (median T(50) 123 vs 113 min, P = 0.042 and 192 vs 113 min, P = 0.003, respectively). Multiple logistic regression analysis showed that age of onset (OR 0.10, CI 0.02-0.52) and sympathetic dysfunction (OR 0.23, CI 0.10-0.51), but not gender (OR 0.76, CI 0.31-1.84) and parasympathetic dysfunction (OR 1.81, CI 0.72-4.56), contributed to gastric retention. CONCLUSIONS AND INFERENCES: Gastric retention is common in hereditary transthyretin amyloidosis early after onset. Autonomic neuropathy only weakly correlates with gastric retention and therefore additional factors must be involved.