Serum transthyretin levels in senile systemic amyloidosis: effects of age,gender and ethnicity

Serum transthyretin (TTR) levels are reduced in familial amyloidotic polyneuropathy (FAP). A single study of patients with senile systemic amyloidosis (SSA) in Sweden found that those individuals also had a significantly lower mean serum TTR concentration than age- and gender-matched controls. To determine if the same phenomenon prevailed in an ethnically more heterogeneous population, we compared the serum TTR levels, as determined by ELISA, in 45 documented SSA patients with congestive heart failure, 20 AL patients with congestive heart failure and population controls. Serum TTR concentrations in the controls were influenced in a statistically significant manner by age, gender and ethnicity. Although it is unlikely that such differences are clinically relevant, they must be considered when assessing the meaning of serum TTR concentrations in any clinically defined population. The serum concentrations in patients with SSA did not differ from age, gender and ethnically matched controls or from a group of AL patients with significant clinical cardiac involvement. We also compared TTR concentrations in 12 African-Americans carrying the TTR V122I allele with those in 826 African-Americans who were homozygous wild type at the TTR locus. The TTR V122I carriers had significantly lower serum TTR concentrations than appropriate controls even though the majority of such individuals had not reached the age of clinical or anatomic risk, i.e. over 60. Thus, as in carriers of other TTR mutations the serum TTR level is lower than normal, despite having a much later appearance of clinical disease.     

Safety and efficacy of long-term diflunisal administration in hereditary transthyretin (ATTR) amyloidosis

Background: A recent 2-year randomized controlled trial indicated that the transthyretin (TTR) tetramer stabilizer, diflunisal, inhibits polyneuropathy progression and preserves quality of life in hereditary ATTR amyloidosis. However, its long-term outcomes are unknown. Here, we report tolerance and efficacy of long-term diflunisal administration in hereditary ATTR amyloidosis.

Methods: Diflunisal was administered orally at 500?mg/day to 40 Japanese hereditary ATTR amyloidosis patents who were not candidates for liver transplantation. The observation period ranged from 2 to 116 months (mean?±?SD: 38.0?±?31.2 months).

Results: Diflunisal-related adverse events included deterioration of renal function and thrombocytopenia resulting in discontinuation of the drug in three patients. Orally administered diflunisal significantly increased serum TTR concentration (p?=?0.001) and stabilized TTR tetramer structure in each patient. Longitudinal analyses of data collected at baseline, 24 months, and after 24 months confirmed sustaining effects of diflunisal on both neurological and cardiac functions. Notably, ulnar compound muscle action potential amplitude, cardiac wall thickness, and ejection fraction were not deteriorated after 24 months of treatment.

Conclusions: Diflunisal was tolerated well by most hereditary ATTR amyloidosis patients, although renal function and blood cell counts must be carefully monitored. Clinical effects of diflunisal were sustained after 2 years of treatment.     

First nationwide survey on systemic wild-type ATTR amyloidosis in Japan

Objective: A nationwide survey on systemic wild-type ATTR (ATTRwt) amyloidosis was conducted to elucidate the frequency, clinical picture and possible diagnostic issues of ATTRwt amyloidosis in Japan.

Methods: A questionnaire was sent to 4629 clinical departments across Japan. A total of 2341 (50.6%) responses were returned completed for further analysis.

Results: Fifty-one patients with ATTRwt amyloidosis (82% male) were identified between January 2012 and December 2014. The study subjects were identified in 11 departments at 10 institutes. The mean age of onset and diagnosis were 71.6 and 73.6?years, respectively. The main clinical findings were cardiac failure (76%), cardiac conduction defects/arrhythmia (59%), renal dysfunction (49%), carpal tunnel syndrome (45%) and spinal canal stenosis (22%).

Conclusions: ATTRwt amyloidosis is diagnosed in a limited number of institutes in Japan and is therefore considered to be underdiagnosed.     

Genetic testing improves identification of transthyretin amyloid (ATTR) subtype in cardiac amyloidosis

Amyloidosis is a group of conditions characterized by the accumulation of amyloid deposits in various tissues. Among these disorders, ATTR amyloidosis occurs either with or without a TTR pathogenic variant. Treatment for amyloidosis depends on the subtype, which is often identified through a tissue biopsy followed by liquid chromatography tandem mass spectrometry (LC–MS/MS). Genetic testing may be done to confirm these results for patients with ATTR amyloidosis; however, the necessity of genetic testing after LC–MS/MS has not been evaluated. A retrospective review identified 153 patients diagnosed with biopsy-proven ATTR amyloidosis, and 56 of these patients underwent both genetic testing and LC–MS/MS. LC–MS/MS and proteomics correctly reported the mutant peptide and heterozygosity in 47/56 (84%) cases. It failed to identify two individuals who were homozygous for the ATTRV122I mutation and failed to detect the following mutations in six other individuals: ATTRA19D, ATTRF44L, ATTRT60A, ATTRI68L and ATTRV122I. Therefore, LC–MS/MS is not sufficient to rule out a pathogenic mutation in cases of ATTR amyloid, and genetic testing should be performed in most cases of ATTR amyloidosis. Correct recognition of hereditary ATTR amyloidosis is important for estimating prognosis, proper familial counselling and guiding use of therapies, such as liver transplantation.     

Ophthalmological manifestations in hereditary transthyretin (ATTR V30M) carriers: a review of 513 cases

Purpose: Assessment of ocular involvement in transthyretin-related familial amyloidosis with polyneuropathy (FAP) in a large cohort of Portuguese patients.

Methods: We reviewed the medical records of 513 Portuguese FAP mutation carriers, at the Ophthalmology Service, Centro Hospitalar do Porto, between 1 January 2008 and 31 January 2013. Abnormal conjunctiva vessels (ACV), Schirmer test, tear break-up time (TBUT), amyloid deposition on the iris (DAI), scalloped iris, amyloid deposition on the anterior capsule of the lens (DAL), vitreous amyloidosis, retinal amyloid angiopathy and glaucoma were evaluated and registered.

Results: Of the 513 carriers, 477 (93%) had clinical systemic disease with a median duration of 9.3 (5.1–13.7) years and 247 were men. Of these, 343 (72%) had been liver transplanted, on median of 6.6 (3.3–10.8) years before inclusion in this study. No ocular abnormalities were identified in the asymptomatic carriers (7%). The abnormalities observed with decreasing frequency were abnormal TBUT (379 patients, 79.5%, 751 eyes), abnormal Schirmer test (320 patients, 67%, 635 eyes), DAI (183 patients, 38.4%, 350 eyes), DAL (157 patients, 32.9%, 308 eyes), scalloped iris (133 patients, 27.9%, 238 eyes), glaucoma (97 patients, 20%, 165 eyes), vitreous amyloidosis (83 patients, 17.4%, 139 eyes), ACV (68 patients, 14%, 136 eyes) and amyloidotic retinal angiopathy (21 patients, 4%, 32 eyes).

Patients with abnormal Schirmer test (p?<?0.001), scalloped iris (p?=?0.006) and vitreous amyloidosis (p?=?0.007) were significantly older than the others. According to their age of onset of systemic disease, the patients have been split into early-onset (<40 years old), intermediate-onset (40–50 years old), late onset (>50 years old) and asymptomatic carriers. We observed a statistically significant difference in the prevalence of ACV (p?=?0.045) and of an abnormal Schirmer test (p?=?0.004) between groups. Transplanted patients have a significantly higher prevalence of DAI (p?=?0.001), DAL (p?=?0.009) and vitreous amyloidosis (p?=?0.025) than non-transplanted patients. Of the 165 eyes with glaucoma, 92.1% had scalloped iris (p?<?0.001) and of 32 eyes with retinal amyloidotic angiopathy, 68.8% had vitreous amyloidosis (p?<?0.001). All prevalences increased with time of disease. The earliest ocular manifestations were abnormal Schirmer test and abnormal TBUT (12% and 17% at 5 years of clinical disease) and the least prevalent was retinal amyloid angiopathy (8% at 15 years of clinical disease).

Conclusion: Ocular disorders in FAP patients are common, and their prevalence increases with disease duration. Prevalence is influenced by several factors, such as the age at onset of FAP and liver transplantation.     

Monoclonal gammopathy of undetermined significance

Significant advances have been made in our understanding of the natural history, pathogenesis, mechanisms of progression and prognosis of monoclonal gammopathy of undetermined significance (MGUS). Although the overall incidence of MGUS progression is 1 per year, it is now possible to more accurately predict the risk of progression based on a new risk-stratification model. However, it is still hard to design chemopreventive trials given that the absolute risk of progression per year is low, even in the high-risk group. Therefore, further improvements in estimating the risk of progression are needed. Roughly 50% of MGUS may originate from primary translocation events at the heavy-chain immunoglobulin locus at chromosome 14q32. In most of the remaining MGUS patients, the initiating event is associated with genomic instability that results in hyperdiploidy of certain odd numbered chromosomes. Cytogenetically distinct subtypes of MGUS may carry significant differences in the risk of progression to malignancy. New markers, such as measures of bone marrow angiogenesis and circulating plasma cells may be additional prognostic factors. A better understanding of the mechanisms underlying the transition of normal plasma cells to the MGUS phenotype, and the transition of MGUS to myeloma or related malignancy, will help identify new risk factors for progression and new targets for chemopreventive interventions.     

Progression of cardiac amyloid deposition in hereditary transthyretin amyloidosis patients after liver transplantation

It has been hypothesized that transthyretin (TTR) amyloidosis may progress after orthotopic liver transplantation (OLT) as a result of continued amyloid fibril synthesis and deposition from normal TTR. To test this hypothesis amyloid fibrils were isolated from cardiac tissues of three patients who died 1½ to 5½ years after OLT: two with Val30Met and one with Thr60Ala TTR. The ratio of variant to normal TTR in each case was determined and compared with the ratio of variant to normal in cardiac tissues from seven patients who died with TTR amyloidosis but who had not had liver transplantation. Tissues from patients with TTR amyloidosis without OLT included three with Val30Met, two with Thr60Ala, one with ΔVal122, and one with Val122Ile. All tissues from patients without OLT had greater amounts of variant TTR than normal TTR except for the Val122Ile in which the ratio was 50:50. The overall median variant to normal ratio was 60:40 with a range of 50–70% variant. In contrast, the mean percentage of variant TTR in the three tissues from patients after OLT was 25% (range 20–35). These data are consistent with the continued deposition of normal TTR in cardiac tissue after liver transplantation.     

Low Prevalence of Clinically Apparent Cardiac Amyloidosis Among Carriers of Transthyretin V122I Variant in a Large Electronic Medical Record

BackgroundTransthyretin (TTR) gene mutations are the most common cause of hereditary amyloidosis. Valine replaced by isoleucine in position 122 (V122I) variant is common, particularly in the black population. Carriers of V122I have increased risk for developing cardiac amyloidosis. Despite a relatively high prevalence, the penetrance of V122I is not firmly established. This study sought to determine the prevalence of clinically apparent cardiac amyloidosis among carriers of the TTR V122I variant.MethodsBioVU, a Vanderbilt University resource linking DNA samples and pre-existing genetic data to de-identified electronic medical records was used to identify TTR V122I mutation carriers. Automated billing code queries (International Classification of Diseases, 9th revision codes), problem list searches, and manual chart reviews were used to identify subjects with clinically diagnosed cardiac amyloidosis.ResultsAmong 28,429 subjects with available genotype data, 129 were V122I carriers. Carriers had a median age of 42 years (interquartile range 16-64). Noncarriers had a median age of 62 years, (interquartile range 41-77). The carrier rate was 3.7% in blacks and 0.02% in whites. Overall, the prevalence of clinically apparent cardiac amyloidosis was 0.8% in carriers and 0.04% in noncarriers (P = .05). Above age 60, the prevalence of cardiac amyloidosis was 2.6% in carriers and 0.06% in noncarriers (P = .03).ConclusionCarriers of the TTR V122I variant are at a higher risk for development of cardiac amyloidosis, particularly at age>60 years. However, clinically apparent cardiac amyloidosis in this population was uncommon. These results support that the penetrance of TTR V122I is age dependent and suggest it may be significantly lower than previously reported.     

Late-onset Hereditary ATTR Amyloidosis with a Novel p.P63S (P43S) Transthyretin Variant

The patient was an 82-year-old Japanese man with no family history suggestive of amyloidosis. He developed bilateral leg edema and shortness of breath and was referred to our hospital. An electrocardiogram showed atrial fibrillation with right bundle branch block. Echocardiography showed concentric LV hypertrophy. An endomyocardial biopsy showed severe ATTR amyloid deposits. A genetic analysis of the transthyretin (TTR) gene revealed a heterozygous c.187C＞T missense variant resulting in p.P63S (P43S). In silico analyses predicted that this variant only modestly altered the structure and function of the TTR protein. The p.P63S variant might be associated with an elderly-onset cardiac-dominant ATTRv phenotype.     

Hereditary transthyretin amyloidosis: baseline characteristics of patients in the NEURO-TTR trial

Abstract

Background: Hereditary transthyretin (ATTRm) amyloidosis is a rare, progressive and fatal disease with a range of clinical manifestations.

Objective: This study comprehensively evaluates disease characteristics in a large, diverse cohort of patients with ATTRm amyloidosis.

Methods: Adult patients (N?=?172) with Stage 1 or Stage 2 ATTRm amyloidosis who had polyneuropathy were screened and enrolled across 24 investigative sites and 10 countries in the NEURO-TTR trial (www.clinicaltrials.gov, NCT01737398). Medical and disease history, quality of life, laboratory data, and clinical assessments were analyzed.

Results: The NEURO-TTR patient population was diverse in age, disease severity, TTR mutation, and organ involvement. Twenty-seven different TTR mutations were present, with Val30Met being the most common (52%). One third of patients reported early onset disease (before age 50) and the average duration of neuropathy symptoms was 5.3 years. Symptoms affected multiple organs and systems, with nearly 70% of patients exhibiting broad involvement of weakness, sensory loss, and autonomic disturbance. Over 60% of patients had cardiomyopathy, with highest prevalence in the United States (72%) and lowest in South America/Australasia (33%). Cardiac biomarker NT-proBNP correlated with left ventricular wall thickness (p<.001). Quality of life, measured by Norfolk QoL-DN and SF-36 patient-reported questionnaires, was significantly impaired and correlated with disease severity.

Conclusions: Baseline data from the NEURO-TTR trial demonstrates ATTRm amyloidosis as a systemic disease with deficits in multiple organs and body systems, leading to decreased quality of life. We report concomitant presentation of polyneuropathy and cardiomyopathy in most patients, and early involvement of multiple body systems.     

Electrophysiological demyelinating features in hereditary ATTR amyloidosis

Objective: To elucidate the electrophysiological demyelinating features in patients with hereditary ATTR amyloidosis that may lead to a misdiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP).

Methods: In 102 patients with hereditary ATTR amyloidosis (85 Val30Met and 17 non-Val30Met; 37 and 65 from endemic and non-endemic areas, respectively), results of motor nerve conduction studies (MNCSs) with a 2-Hz low-cut filter in the unilateral ulnar and tibial nerves were retrospectively investigated to assess whether each MNCS parameter demonstrated demyelinating features that fulfil the European Federation of Neurological Societies/Peripheral Nerve Society electrodiagnostic (EFNS/PNS EDX) criteria for CIDP.

Results: Thirteen patients with low compound muscle action potential (CMAP) amplitude in the tibial nerve (0.7?±?0.7?mV) and prolonged distal CMAP duration in the ulnar nerve satisfied the definite EFNS/PNS EDX criteria for CIDP. Abnormal temporal dispersion and prolongation of distal latency in the tibial nerve were observed in 5 of 13 patients. However, only one of the 13 patients presented with the reduction of motor conduction velocity in each nerve. No patient exhibited conduction block in any nerve.

Conclusion: Patients with hereditary ATTR amyloidosis occasionally show electrophysiological demyelinating features without conduction block following severe axonal degeneration.     

Personalized medicine approach for optimizing the dose of tafamidis to potentially ameliorate wild-type transthyretin amyloidosis (cardiomyopathy)

Placebo-controlled clinical trials are useful for identifying the dose of a drug candidate that produces a meaningful clinical response in a patient population. Currently, Pfizer, Inc. is enrolling a 400-person clinical trial to test the efficacy of 20 or 80?mg of tafamidis to ameliorate transthyretin (TTR)-associated cardiomyopathy using clinical endpoints. Herein, we provide guidance for how to optimize the dose of tafamidis for each WT TTR cardiomyopathy patient using its mechanism of action as the key readout, i.e. we identify the dose of tafamidis that maximally kinetically stabilizes TTR in the blood. Tetramer dissociation is rate limiting for TTR aggregation, which appears to drive the pathology of the TTR amyloidoses. Hence, we measure the TTR tetramer dissociation rate (kinetic stability) in the patient's plasma as a function of tafamidis dose to optimize the dose employed to maximize kinetic stability. Historical data tell us that a subset of patients exhibiting higher tafamidis plasma concentrations are maximally kinetically stabilized at the 20-mg tafamidis dose, whereas the patient studied herein required a 60?mg once daily dose to achieve maximum kinetic stabilization. We anticipate that establishing the dose of tafamidis that achieves maximal TTR kinetic stabilization will translate into a maximal clinical effect, but that remains to be demonstrated.

Trial registration: ClinicalTrials.gov identifier: NCT01994889.     

Monoclonal gammopathy of undetermined significance (MGUS) in patients with solid tumors: effects of chemotherapy on the monoclonal protein

The aim of this study was to assess the effect of systemic chemotherapy on the monoclonal protein levels of patients with solid tumors who also have a monoclonal gammopathy of undetermined significance (MGUS). All patients with solid tumors who were referred to our department for consideration of systemic chemotherapy were evaluated with serum protein electrophoresis (SPEP) for the presence of MGUS. When MGUS was confirmed with immunofixation, serial SPEP was performed during and after completion of chemotherapy. Over a 6-year period, 21 patients with solid tumors and MGUS were prospectively identified and assessed. At least 50% reduction of serum monoclonal protein was noted in 4 of 11 patients treated with paclitaxel or docetaxel with a platinum analogue and in 5 of 7 patients who received an irinotecan-containing regimen. Our data indicate that in MGUS patients treated with irinotecan-containing chemotherapy regimens, a high incidence of reduction in their monoclonal protein levels is observed. Since topotecan, another topoisomerase I inhibitor, has some activity in multiple myeloma, further evaluation of irinotecan may be warranted. Evaluation of larger numbers of MGUS patients treated with chemotherapy for their underlying malignancy may help identify in vivo potentially active agents and regimens for patients with overt myeloma.     

Monoclonal gammopathy of undetermined significance in atomic bomb survivors: incidence and transformation to multiple myeloma

Among 6737 atomic bomb survivors who did not have monoclonal gammopathy at the first examination, 112 developed monoclonal gammopathy of undetermined significance (MGUS) between 1985 and 2001. The crude incidence rate was 164 per 100 000 person-years in the overall study population, with a sharp increase in incidence after age 60 years. The incidence was not significantly associated with radiation dose (P = 0.91), although the incidence at less than 80 years of age showed a marginally significant association (P = 0.05). Among 75 patients with MGUS detected in 1985, 50 patients (67%) had died by 2001, 16 (21%) of these deaths were due to multiple myeloma (MM). MM mortality among MGUS patients was 2284 per 100 000 person-years while the rate in the total population was 14.6 per 100 000 person-years. The risk of MM mortality was greater in the older generation. The transformation from MGUS to MM was faster in exposed persons than in non-exposed persons, but this was not statistically significant.     

Monoclonal gammopathies of undetermined significance

The monoclonal gammopathies include multiple myeloma (MM), monoclonal gammopathy of undetermined significance (MGUS), primary systemic amyloidosis (AL), and Waldenstr?m's macroglobulinemia (WM). At Mayo Clinic, almost 60% of patients with a monoclonal gammopathy have MGUS. MGUS is characterized by the presence of a serum monoclonal protein value <3 g/dL, fewer than 10% plasma cells in the bone marrow, no or a small amount of monoclonal protein in the urine, and absence of lytic bone lesions, anemia, hypercalcemia, or renal insufficiency related to the plasma-cell proliferative process. During long-term follow-up of 241 patients with MGUS seen at Mayo Clinic from 1956 to 1970, MM, WM, AL, or a related disorder developed in 64. To confirm the findings, we conducted a population-based study on MGUS in the 11 counties of southeastern Minnesota from 1960 to 1994. The risk of progression to a malignant plasma-cell disorder was 1% per year.     

Impact of liver transplantation on the natural history of oculopathy in Portuguese patients with transthyretin (V30M) amyloidosis

Purpose: Evaluation of the impact of liver transplantation in the natural history of ocular disorders in familial amyloidotic polyneuropathy (FAP) amyloidosis TTR V30M related (ATTR V30M) patients.

Design: A clinical, retrospective and cross-sectional study of 64 Portuguese FAP ATTR V30M patients was carried out between January 2005 and December 2011.

Methods: Thirty-two liver transplanted patients (both eyes) aged 39.6–53.8 years old, 32/32 male/female, were paired with an equal number of non-transplanted patients, matching for age, gender, age at onset, disease duration and gender of transmitting parent. Intervention or observation procedure: Routine ophthalmological observation. Main outcome measures: Slit-lamp observation for abnormal conjunctival vessels (ACV), tears break-up time, iris, lens; fundus observation for vitreous, retina and optic disc; Schirmer test.

Results: Liver transplantation had no influence on tears break-up time, deposition of amyloid on the iris and retinal amyloid angiopathy. Slight, non-statistically significant protective effects of liver transplantation were noted in the first years for some ocular manifestations (ACV and scalloped iris), except for the abnormal Schirmer test, which was significantly more prevalent in non-transplanted patients’ eyes (81% versus 56%, p?=?0.002). On the other hand, deposition of amyloid on the lens, vitreous amyloidosis and glaucoma were apparently more common in transplanted patients. Those differences tended to disappear with time.

Conclusions: Ocular manifestations of FAP were not influenced by liver transplantation in a meaningful way. Both transplanted and non-transplanted FAP patients need similar regular follow-up due to long-term risk of serious ocular disease.