Phenotypic expression of familial amyloid polyneuropathy in Brazil

Hereditary Transthyretin Amyloidosis (hATTR) with Polyneuropathy Clusters Are Located in Ancient Mining Districts: A Possible Geochemical Origin of the Disease

Hereditary transthyretin amyloidosis (hATTR) with polyneuropathy (formerly known as Familial Amyloid Polyneuropathy (FAP)) is an endemic amyloidosis involving the harmful aggregation of proteins, most commonly transthyretin (TTR) but sometimes also apolipoprotein A-1 or gelsolin. hATTR appears to be transmitted as an autosomal dominant trait. Over 100 point mutations have been identified, with the Val30Met substitution being the most common. Yet, the mechanism of pathogenesis and the overall origin of hATTR remain unclear. Here, we argue that hATTR could be related to harmful metal exposure. hATTR incidence is unevenly distributed globally, and the three largest defined clusters exist in Japan, Portugal, and Sweden. All three disease regions are also ancient mining districts with associated metal contamination of the local environment. There are two main mechanisms for how harmful metals, after uptake into tissues and body fluids, could induce hATTR. First, the metals could directly influence the expression, function, and/or aggregation of the proteins involved in hATTR pathology. Such metal-protein interactions might constitute molecular targets for anti-hATTR drug design. Second, metal exposure could induce hATTR -associated genetic mutations, which may have happened several generations ago. These two mechanisms can occur in parallel. In conclusion, the possibility that hATTR could be related to metal exposure in geochemically defined regions deserves further attention.

Brazilian consensus for diagnosis, management and treatment of hereditary transthyretin amyloidosis with peripheral neuropathy: second edition

Hereditary transthyretin amyloidosis with peripheral neuropathy (ATTRv-PN) is an autosomal dominant inherited sensorimotor and autonomic polyneuropathy with over 130 pathogenic variants identified in the TTR gene. Hereditary transthyretin amyloidosis with peripheral neuropathy is a disabling, progressive and life-threatening genetic condition that leads to death in ∼ 10 years if untreated. The prospects for ATTRv-PN have changed in the last decades, as it has become a treatable neuropathy. In addition to liver transplantation, initiated in 1990, there are now at least 3 drugs approved in many countries, including Brazil, and many more are being developed. The first Brazilian consensus on ATTRv-PN was held in the city of Fortaleza, Brazil, in June 2017. Given the new advances in the area over the last 5 years, the Peripheral Neuropathy Scientific Department of the Brazilian Academy of Neurology organized a second edition of the consensus. Each panelist was responsible for reviewing the literature and updating a section of the previous paper. Thereafter, the 18 panelists got together virtually after careful review of the draft, discussed each section of the text, and reached a consensus for the final version of the manuscript.

Cardiovascular Involvement in Transthyretin Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) is a systemic disorder resulting from the extracellular deposition of amyloid fibrils of misfolded transthyretin protein in the heart. ATTR-CA is a life-threatening disease, which can be caused by progressive deposition of wild type transthyretin (wtATTR) or by aggregation of an inherited mutated variant of transthyretin (mATTR). mATTR Is a rare condition transmitted in an autosomal dominant manner with incomplete penetrance, causing heterogenous phenotypes which can range from predominant neuropathic involvement, predominant cardiomyopathy, or mixed. Diagnosis of ATTR-CA is complex and requires integration of different imaging tools (echocardiography, bone scintigraphy, magnetic resonance) with genetics, clinical signs, laboratory tests, and histology. In recent years, new therapeutic agents have shown good efficacy and impact on survival and quality of life in this subset of patients, nevertheless patients affected by ATTR-CA may still carry an unfavorable prognosis, thus highlighting the need for new therapies. This review aims to assess cardiovascular involvement, diagnosis, and management of patients affected by ATTR-CA.

Hereditary transthyretin-mediated amyloidosis with polyneuropathy: baseline anthropometric, demographic and disease characteristics of patients from a reference center

BACKGROUND

Hereditary transthyretin-mediated (hATTR) amyloidosis with polyneuropathy is a rare, inherited, multisystem, and often fatal disease caused by a variant in transthyretin (TTR) gene. Baseline characteristics of patients, especially anthropometric data, are scarce in the literature, and they are relevant to define effective treatment strategies.

OBJECTIVE

This study aimed to describe baseline demographic, anthropometric, and disease characteristics in a cohort of patients from a reference center in Brazil.

METHODS

Symptomatic patients not previously included in clinical trials and eligible for treatment were enrolled. Ethnicity, state of residence, age, sex, weight, height, body mass index (BMI), TTR variant, and Polyneuropathy Disability Score (PND) at diagnosis were analyzed.

RESULTS

Among the 108 patients enrolled, 58.33% were male, 60.19% were Caucasian, and 83.33% lived in the Southeast region. Mean age was 51.61 (±16.37) years, mean weight was 65.76 (±15.16) kg, mean height was 168.33 (±10.26) cm, and mean BMI was 23.11 (±4.45) kg/m2. The most prevalent variant was V30M (86.11%). Patients with PND score 0 presenting autonomic neuropathy were 14.81%. Patients with PND score I-II and III-IV were 52.78 and 32.41%, respectively. Mean weight and BMI were significantly lower in patients with sensory-motor manifestations.

CONCLUSIONS

This is the largest cohort of patients in Brazil for whom anthropometric characteristics have been described. Baseline demographic, anthropometric, and disease data indicate that delay in diagnosis of hATTR amyloidosis with polyneuropathy is still a problem and that efforts must be made to expedite diagnosis and maximize opportunities for new disease-modifying treatments.

Dysautonomia: A Forgotten Condition - Part 1

Dysautonomia covers a range of clinical conditions with different characteristics and prognoses. They are classified as Reflex Syndromes, Postural Orthostatic Tachycardia Syndrome (POTS), Chronic Fatigue Syndrome, Neurogenic Orthostatic Hypotension (nOH) and Carotid Sinus Hypersensitivity Syndrome. Reflex (vasovagal) syndromes will not be discussed in this article. Reflex (vasovagal) syndromes are mostly benign and usually occur in patients without an intrinsic autonomic nervous system (ANS) or heart disease. Therefore, they are usually studied separately. Cardiovascular Autonomic Neuropathy (CAN) is the term most currently used to define dysautonomia with impairment of the sympathetic and/or parasympathetic cardiovascular autonomic nervous system. It can be idiopathic, such as multisystemic atrophy or pure autonomic failure, or secondary to systemic pathologies such as diabetes mellitus, neurodegenerative diseases, Parkinson's disease, dementia syndromes, chronic renal failure, amyloidosis and it may also occur in the elderly. The presence of Cardiovascular Autonomic Neuropathy (CAN) implies greater severity and worse prognosis in various clinical situations. Detection of Orthostatic Hypotension (OH) is a late sign and means greater severity in the context of dysautonomia, defined as Neurogenic Orthostatic Hypotension (nOH). It must be differentiated from hypotension due to hypovolemia or medications, called non-neurogenic orthostatic hypotension (nnOH). OH can result from benign causes, such as acute, chronic hypovolemia or use of various drugs. However, these drugs may only reveal subclinical pictures of Dysautonomia. All drugs of patients with dysautonomic conditions should be reevaluated. Precise diagnosis of CAN and the investigation of the involvement of other organs or systems is extremely important in the clinical suspicion of pandysautonomia. In diabetics, in addition to age and time of disease, other factors are associated with a higher incidence of CAN, such poor glycemic control, hypertension, dyslipidemia and obesity. Among diabetic patients, 38-44% can develop Dysautonomia, with prognostic implications and higher cardiovascular mortality. In the initial stages of DM, autonomic dysfunction involves the parasympathetic system, then the sympathetic system and, later on, it presents as orthostatic hypotension. Valsalva, Respiratory and Orthostatic tests (30:15) are the gold standard methods for the diagnosis of CAN. They can be associated with RR Variability tests in the time domain, and mainly in the frequency domain, to increase the sensitivity (protocol of the 7 tests). These tests can detect initial or subclinical abnormalities and assess severity and prognosis. The Tilt Test should not be the test of choice for investigating CAN at an early stage, as it detects cases at more advanced stages. Tilt response with a dysautonomic pattern (gradual drop in blood pressure without increasing heart rate) may suggest CAN. Treatment of patients at moderate to advanced stages of dysautonomia is quite complex and often refractory, requiring specialized and multidisciplinary evaluation. There is no cure for most types of Dysautonomia at a late stage. NOH patients can progress with supine hypertension in more than 50% of the cases, representing a major therapeutic challenge. The immediate risk and consequences of OH should take precedence over the later risks of supine hypertension and values greater than 160/90 mmHg are tolerable. Sleeping with the head elevated (20-30 cm), not getting up at night, taking short-acting antihypertensive drugs for more severe cases, such as losartan, captopril, clonidine or nitrate patches, may be necessary and effective in some cases. Preventive measures such as postural care; good hydration; higher salt intake; use of compression stockings and abdominal straps; portioned meals; supervised physical activity, mainly sitting, lying down or exercising in the water are important treatment steps. Various drugs can be used for symptomatic nOH, especially fludrocortisone, midodrine and droxidopa, the latter not available in Brazil. The risk of exacerbation or triggering supine hypertension should be considered. Chronic Fatigue Syndrome represents a form of Dysautonomia and has been renamed as a systemic disease of exercise intolerance, with new diagnostic criteria: 1 - Unexplained fatigue, leading to occupational disability for more than 6 months; 2 - Feeling ill after exercising; 3 - Non-restorative sleep; 4 - One of the following findings: cognitive impairment or orthostatic intolerance. Several pathologies today have evolved with chronic fatigue, being called chronic diseases associated with chronic fatigue. Postural orthostatic tachycardia syndrome (POTS), another form of presentation of dysautonomic syndromes, is characterized by sustained elevation of heart rate (HR) ≥30 bpm (≥40 bpm if <20 years) or HR ≥120 bpm, in the first 10 minutes in an orthostatic position or during the tilt test, without classical orthostatic hypotension associated. A slight decrease in blood pressure may occur. Symptoms appear or get worse in an orthostatic position, with dizziness, weakness, pre-syncope, palpitations, and other systemic symptoms being common.

Brazilian consensus for diagnosis, management and treatment of transthyretin familial amyloid polyneuropathy

Transthyretin familial amyloid polyneuropathy is an autosomal dominant inherited sensorimotor and autonomic polyneuropathy, which if untreated, leads to death in approximately 10 years. In Brazil, liver transplant and tafamidis are the only disease-modifying treatments available. This review consists of a consensus for the diagnosis, management and treatment for transthyretin familial amyloid polyneuropathy from the Peripheral Neuropathy Scientific Department of the Brazilian Academy of Neurology. The first and last authors produced a draft summarizing the main views on the subject and emailed the text to 10 other specialists. Relevant literature on this subject was reviewed by each participant and used for the individual review of the whole text. Each participant was expected to review the text and send a feedback review by e-mail. Thereafter, the 12 panelists got together at the city of Fortaleza, discussed the controversial points, and reached a consensus for the final text.

Epidemiology of ATTRV30M neuropathy in Cyprus and the modifier effect of complement C1q on the age of disease onset

BACKGROUND

ATTRV30M amyloidosis is a lethal autosomal dominant sensorimotor and autonomic neuropathy caused by amyloid deposition composed of aggregated misfolded TTR monomers with the V30M mutation. The age of onset in patients with ATTRV30M varies in different foci and the mechanism behind it is still unknown.

METHODS

The tertiary neurology center following all ATTRV30M patients in Cyprus was used to collect demographic data to estimate; prevalence, incidence, penetrance, anticipation, time from disease onset to diagnosis and transplantation. Ocular, cardiac and leptomeningeal involvement in transplanted patients was explored. Correlation of C1q tagging SNPs with age of disease onset was carried out.

RESULTS

Prevalence and incidence for ATTRV30M neuropathy in Cyprus are 5.4/100,000 and 0.3/100,000 respectively. Mean age of onset is 40.6 years and anticipation is 8.3 years. Penetrance reaches 51% and 75% by the ages of 50 and 80 years respectively. In liver transplanted patients rates of ocular, cardiac and leptomeningeal involvement were estimated to be 60%, 20% and 16%, respectively. C1q polymorphisms correlated with age of disease onset.

CONCLUSIONS

ATTRV30M neuropathy has a rising prevalence in Cyprus due to improved survival of patients. Late onset complications are becoming a major problem. Complement C1q appears to be a modifier in this disease.

Transthyretin V122I amyloidosis with clinical and histological evidence of amyloid neuropathy and myopathy

Hereditary transthyretin amyloidosis (ATTR) is a genetically and clinically heterogeneous disease manifesting with predominant peripheral and autonomic neuropathy; cardiomyopathy, or both. ATTR V122I is the most common variant associated with non-neuropathic familial amyloid cardiomyopathy. We present an unusual case of V122I amyloidosis with features of amyloid neuropathy and myopathy, supported by histological confirmation in both sites and diffuse tracer uptake on (99m)Tc-3,3-Diphosphono-1,2-Propanodicarboxylic acid (DPD) scintigraphy throughout skeletal and cardiac muscle. A 64 year old Jamaican man presented with cardiac failure. Cardiac MR revealed infiltrative cardiomyopathy; abdominal fat aspirate confirmed the presence of amyloid, and he was homozygous for the V122I variant of transthyretin. He also described general weakness and EMG demonstrated myopathic features. Sural nerve and vastus lateralis biopsy showed TTR amyloid. The patient is being treated with diflunisal, an oral TTR stabilising agent. Symptomatic myopathy and neuropathy with confirmation of tissue amyloid deposition has not previously been described. Extracardiac amyloidosis has implications for diagnosis and treatment.

Asp58Ala is the predominant mutation of the TTR gene in Korean patients with hereditary transthyretin-related amyloidosis

Hereditary transthyretin (TTR)-related amyloidosis (ATTR) seems to be a rare autosomal-dominant inherited form of systemic amyloidosis. Studies indicate considerable heterogeneity in the disease's presentation and genotype; however, there is little data from Korea, where the prevalence of hereditary ATTR is very low. In this study, we investigated the phenotypic and genotypic spectra of hereditary ATTR in Korea. Direct sequencing analysis was performed to detect TTR gene mutations in amyloidosis patients whose results of TTR immunohistochemical staining were positive or equivocal. Clinical presentation was categorized as exclusively cardiac, exclusively neurologic, or mixed phenotype. Of 12 genetic tests performed, seven were positive for TTR mutations. D58A (c.173A>C) was the most common mutation in this study (57%, 4/7). The majority of those patients with hereditary ATTR had the mixed phenotype (86%, 6/7). The patients with D58A mutation had older ages of disease onset (median, 61 years vs. 42 years; P = 0.08), and a higher incidence of gastrointestinal involvement (75% vs. 0%; P = 0.03) than those with other identified TTR mutations. A significant male predominance was also noted in this study (P = 0.01).

The "Wagshurst study": p.Val40Ile transthyretin gene variant causes late-onset cardiomyopathy

BACKGROUND

Transthyretin-related amyloidosis (ATTR) is characterized by a wide heterogeneity of genotypes and predominantly neurological and cardiac phenotypes. This study aims to characterize a cohort of patients with the rare transthyretin (TTR) Val20Ile (p.TTRVal40Ile) variant.

METHODS AND RESULTS

This study comprises a single-center cohort of 59 individuals subsequently evaluated for TTRVal20Ile variant due to clinical (n = 13) or predictive (n = 46) reasons. All patients were mainly related to Wagshurst, a small village in the South of Germany. Clinical assessment was performed by neurological evaluation, echocardiography, electrocardiography, cardiac biomarkers, cardiac MRI (n = 13), and (99m)Tc-DPD scintigraphy (n = 16). The rare TTRVal20Ile variant was found in 41 patients; evidence of cardiac amyloidosis was present in 22 patients. Evidence of pulmonary involvement was obtained by (99m)Tc-DPD scintigraphy in eight patients. No further organ involvement was observed in any of the patients carrying TTRVal20Ile variant. Correlation of inter-ventricular septum thickness as well as decrease of left ventricular longitudinal contractility with age was observed. Moreover, thickness of inter-ventricular septum correlated with NT-proBNP plasma levels and decrease in mitral annular plane systolic excursion. Cardiac manifestation started during the early sixth life decade indicated by higher left ventricular septum thickness and NT-proBNP plasma levels as compared to patients in fifth decade of life. All patients of the seventh and eighth life decade (n = 10) presented with cardiac amyloidosis. During median follow-up of 26 (0-108) months, eight patients underwent heart transplantation with 1-year mortality rate of 25%.

CONCLUSIONS

This large cohort of individuals carrying the TTRVal20Ile mutation reveals a predominantly cardiac phenotype with high penetrance and late onset of symptoms. Cardiac manifestation progressed to end-stage heart failure within a few years, finally requiring heart transplantation with promising long-term survival rates.

Epidemiology of transthyretin-associated familial amyloid polyneuropathy in the Majorcan area: Son Llàtzer Hospital descriptive study

Background

Transthyretin-associated Familial Amyloid Polyneuropathy (TTR-FAP) is an autosomal dominant disease caused by the deposition of abnormal transthyretin that results from a gene mutation. Although rare worldwide, there are descriptions of several endemic foci, such as in Majorca, Balearic Islands, Spain. We aimed at describing a contemporary series of TTR-FAP patients in Son Llàtzer Hospital in Majorca from an epidemiological point of view in order to report their main clinical and laboratory characteristics.

Methods

A retrospective, observational study was performed. Medical records from adult patients diagnosed with TTR-FAP from a single hospital were reviewed.

Results

Out of a total of 107 cases, 75 subjects were included: asymptomatic carriers (52.3%) and symptomatic patients (47.7%). Mean age was 58.3 years at the time of the study, and 50.7% were men. Mean age at diagnosis was 49.8 years. In addition, 42 patients (39.2%) had received a liver transplant, and time to liver transplantation was on average 29.56 months from the initial diagnosis. They all had the Val30Met mutation. The organs of the nervous system were those most frequently impaired (57.3%), and 83.9% of the symptomatic patients were fully ambulant (stage 1). Family history was reported in 69.3% of the cases, with the patient’s father being the most commonly affected relative. Comorbidities were frequent, with high blood pressure being the most common.

Conclusions

Our findings provide additional information on this condition and are useful for describing the demographic features, clinical presentation, diagnosis, and natural course of TTR-FAP in Majorca.

Familial Transthyretin Amyloidosis with Variant Asp38Ala Presenting with Orthostatic Hypotension and Chronic Diarrhea

A 53-year-old man complained of orthostatic, non-rotating dizziness, and chronic watery diarrhea of several years duration. His nerve-conduction velocity test revealed peripheral sensory-motor polyneuropathy and he showed an autonomic function abnormality. Echocardiographic examination showed ventricular and atrial wall thickening with a granular "sparkling" appearance. Left ventricular systolic function was preserved but pseudonormal diastolic dysfunction was present. Coronary angiography showed normal coronary arteries and an endomyocardial biopsy revealed lesions consistent with cardiac amyloidosis. Colonoscopic biopsy also revealed the deposition of amyloid fibrils. Gene analysis found the transthyretin variant Asp38Ala. His son had same mutation, but three daughters did not. In conclusion, we report a case of familial transthyretin amyloidosis with Asp38Ala.

Disease profile and differential diagnosis of hereditary transthyretin-related amyloidosis with exclusively cardiac phenotype: an Italian perspective

AIMS

Hereditary transthyretin (TTR)-related amyloidosis (ATTR) is mainly considered a neurologic disease. We assessed the phenotypic and genotypic spectra of ATTR in a Caucasian area and evaluated the prevalence, genetic background, and disease profile of cases with an exclusively cardiac phenotype, highlighting possible hints for the differential diagnosis with hypertrophic cardiomyopathy (HCM) and senile systemic amyloidosis (SSA).

METHODS AND RESULTS

In this Italian multicentre study, 186 patients with ATTR were characterized at presentation. Thirty patients with SSA and 30 age-gender-matched HCM patients were used for comparison. Phenotype was classified as exclusively cardiac (n = 31, 17%), exclusively neurologic (n = 46, 25%), and mixed cardiac/neurologic (n = 109, 58%). Among the eight different mutations responsible for an exclusively cardiac phenotype, Ile68Leu was the most frequent. Five patients with an exclusively cardiac phenotype developed mild abnormalities at neurological examination, but no symptoms during a 36-month follow-up (range: 14-50). Exclusively cardiac phenotype was characterized by male gender, age >65 years, heart failure symptoms, symmetric left ventricular (LV) 'hypertrophy', and moderately depressed LV ejection fraction. This profile was similar to SSA, but relatively distinct from HCM. Compared with patients with a mixed phenotype, patients with an exclusively cardiac phenotype showed a more pronounced cardiac involvement on both echocardiogram and electrocardiogram (ECG).

CONCLUSION

A clinically relevant subset of Caucasian ATTR patients present with an exclusively cardiac phenotype, mimicking HCM or SSA. Echocardiographic and ECG findings are useful to differentiate ATTR from HCM but not from SSA. The role of liver transplantation in these patients should be reconsidered.

Transthyretin-related amyloidoses and the heart: a clinical overview

A nonhereditary form of systemic amyloidosis associated with wild-type transthyretin causes heart involvement predominantly in elderly men (systemic senile amyloidosis, or SSA). However, hereditary transthyretin-related amyloidosis (ATTR) is the most frequent form of familial systemic amyloidosis, a group of severe diseases with variable neurological and organ involvement. ATTR remains a challenging and widely underdiagnosed condition, owing to its extreme phenotypic variability: the clinical spectrum of the disease ranges from an almost exclusive neurologic involvement to a strictly cardiac presentation. Such heterogeneity principally results from differential effects of the various reported transthyretin mutations, the geographic region the patient is from and, in the case of the most common mutation, Val30Met, whether or not large foci of cases occur (endemic versus nonendemic aggregation). Genetic or environmental factors (such as age, sex, and amyloid fibril composition) also contribute to the heterogeneity of ATTR, albeit to a lesser extent. The existence of exclusively or predominantly cardiac phenotypes should lead clinicians to consider the possibility of ATTR in all patients who present with an unexplained increase in left ventricular wall thickness at echocardiography. Assessment of such patients should include an active search for possible red flags that can point to the correct final diagnosis.

Systemic cardiac amyloidoses: disease profiles and clinical courses of the 3 main types

BACKGROUND

Most studies of amyloidotic cardiomyopathy consider as a single entity the 3 main systemic cardiac amyloidoses: acquired monoclonal immunoglobulin light-chain (AL); hereditary, mutated transthyretin-related (ATTRm); and wild-type transthyretin-related (ATTRwt). In this study, we compared the diagnostic/clinical profiles of these 3 types of systemic cardiac amyloidosis.

METHODS AND RESULTS

We conducted a longitudinal study of 233 patients with clear-cut diagnosis by type of cardiac amyloidosis (AL, n=157; ATTRm, n=61; ATTRwt, n=15) at 2 large Italian centers providing coordinated amyloidosis diagnosis/management facilities since 1990. Average age at diagnosis was higher in AL than in ATTRm patients; all ATTRwt patients except 1 were elderly men. At diagnosis, mean left ventricular wall thickness was higher in ATTRwt than in ATTRm and AL. Left ventricular ejection fraction was moderately depressed in ATTRwt but not in AL or ATTRm. ATTRm patients less often displayed low QRS voltage (25% versus 60% in AL; P<0.0001) or low voltage-to-mass ratio (1.1+/-0.5 versus 0.9+/-0.5; P<0.0001). AL patients appeared to have greater hemodynamic impairment. On multivariate analysis, ATTRm was a strongly favorable predictor of survival, and ATTRwt predicted freedom from major cardiac events.

CONCLUSIONS

AL, ATTRm, and ATTRwt should be considered 3 different cardiac diseases, probably characterized by different pathophysiological substrates and courses. Awareness of the diversity underlying the cardiac amyloidosis label is important on several levels, ranging from disease classification to diagnosis and clinical management.

Epidemiological, clinical and genetic study of familial amyloidotic polyneuropathy in Cyprus

OBJECTIVES. To define the incidence and prevalence of familial amyloidotic polyneuropathy (FAP) TTRVal30Met on the island of Cyprus. To study the clinical phenotype and genetic features of FAP TTRVal30Met in the Cypriot population.

METHODS

The clinical and neurogenetic databases were used to identify probands with FAP TTRVal30Met and detailed family trees were constructed. Potential carriers of the mutation were identified from the family trees and assessed clinically and genetically. Transthyretin was completely sequenced in patients and potential carriers.

RESULTS

Thirty-six patients carrying the TTRVal30Met mutation (one homozygote) from 22 families were identified. On 1 December 2003 the prevalence of FAP was 3.72/100,000 while the incidence is estimated to be 0.69/100,000 per year. The phenotype observed was characteristic for a length dependent sensorimotor and autonomic neuropathy with neuropathic pain. Mean age of onset was 46 years. Penetrance is estimated to be 28% and positive anticipation in the age of onset is found.

CONCLUSION

FAP is relatively prevalent in Cyprus which may be considered as another endemic focus of the disease in Europe. The mean age of onset and penetrance is different from the Portuguese and Swedish populations. Understanding the biological factors that determine these differences could potentially lead to therapeutic advances.

Transthyretin is up-regulated by sex hormones in mice liver

Misfolding and aggregation of mutated and wild-type transthyretin (TTR) can cause familial amyloid polyneuropathy (FAP) and senile systemic amyloidosis (SSA), respectively. In some populations, FAP onset seems to occur on average 2-11 years earlier in men than in women, and SSA appears to be a disease of elderly men. Most (95-100%) SSA patients described in the literature are men, suggesting that amyloid deposition in these patients may be sex hormone related. On the basis of gender-related differences in FAP onset, and on the almost exclusivity of SSA in elder men, we hypothesize that, sex hormones may increase TTR synthesis by the liver, and therefore, may contribute to amyloid deposition. In order to test this hypothesis, castrated female and male mice were implanted with alzet mini-osmotic pumps, delivering 17beta-estradiol (E2) or 5alpha-dihydrotestosterone (DHT), or vehicle only, for 1 week. Sham operated animals were also included in the experiment. After hormonal stimulation, mice were euthanized under anaesthesia, and liver and sera were collected. The expression of TTR in liver, and the levels of TTR in sera in response to E2 and DHT were analysed by Real Time PCR and radioimmunoassay, respectively. Data analysis showed that, both hormones induced TTR transcription, which was concurrent with a consistent increase in the circulating levels of the protein. Taken together, all these data provide an indication that sex hormone stimulation may constitute a risk factor for SSA.

On the origin of the transthyretin Val30Met familial amyloid polyneuropathy

Transthyretin (TTR) familial amyloid polyneuropathy is a severe autosomal dominant neuropathy of adulthood, frequently linked to the pathogenic Val30Met variant of the TTR gene. The condition was initially described in northern Portugal, which is the first focus of the disease. Other important clusters of families are found in Sweden, Japan and South America. The origin of the Val30Met mutation and its distribution through the populations remains unclear. In the present work, we aimed at refining the history of the Val30Met mutation in patients affected with TTR amyloid neuropathy from Portugal, Sweden and Brazil. The decay of haplotype sharing was studied in 60 patients to estimate the age of the Most Recent Common Ancestor (MRCA) of mutation carriers in these populations. Our results showed a common haplotype in Portuguese and Brazilian patients and an age estimate of the MRCA of 750 and 650 years, respectively. In contrast, a different haplotype was found in the Swedish Val30Met patients with a corresponding age estimate for the MRCA, of 375 years. This work strengthens the hypothesis of different founders in Portuguese and Swedish Val30Met carriers and suggested a Portuguese origin of the Brazilian mutation. The age estimates of the MRCA are in line with the current historical knowledge of these populations.

Gender-related risk of myocardial involvement in systemic amyloidosis

To investigate associations between gender and myocardial involvement in systemic amyloidosis, we reviewed all patients presenting between 1994 and September 2006 in our institutional network (100 AL and 98 familial transthyretin-related amyloidosis (ATTR) patients, plus 12 elderly men with senile systemic amyloidosis). We focused on echocardiographic descriptors of myocardial involvement (height-indexed mean left ventricular (LV) wall thickness, LV mass index), and baseline LV function. Among familial ATTR patients, female prevalence was lower within the highest tertile of either echocardiographic indicator of myocardial involvement. Gender was independently associated with height-indexed mean LV wall thickness (as were gene mutations). Female prevalence appeared rather similar across the different neurological stages. Within the subgroup of familial ATTR patients with amyloidotic cardiomyopathy, women tended to display a considerably less severe morphological and functional echocardiographic profile. We explored the possible role of female sex hormones by considering menopausal status: women in the highest tertile of mean LV wall thickness index were more often postmenopausal than those in the other two tertiles and had a much higher ( approximately 15 years) mean age; analogous age-related associations were not observable for men. In conclusion, these findings raise the hypothesis that some biological characteristic associated with female gender protects against myocardial involvement in familial ATTR.

Les amyloses à transthyrétine

PURPOSE

Transthyretin amyloidoses are the most common form of amyloidosis. Two different types of transthyretin amyloidoses are described, one is rare, familial, its precursor is the mutated transthyretin, this type is called transthyretin amyloid, the other is more common, its precursor is wild transthyretin, this second type is called senile amyloid. The review describes the molecular, clinical and evolutives features of both types.

CURRENT KNOWLEDGE AND KEY POINTS

Transthyretin is a naturally beta-pleated protein. Reported mutations increase its proteolysis resistance and its ability to form amyloid deposits. While transthyretin amyloid is clinically aggressive (neuropathy, cardiomyopathy, nephropathy, and vitreous deposits), senile amyloid is slightly symptomatic (rarely congestive heart failure). The differential diagnosis is essentially based on molecular biology.

FUTURE PROSPECTS AND PROJECTS

Liver transplantation is an effective treatment of transthyretin amyloid because it switches the mutated protein synthesis to the wild protein synthesis. Liver transplantation is sometimes associated with cardiac or kidney transplantation depending of the clinical presentation. Concerning a specific treatment, P component analogous are developed for inhibiting amyloid deposits formation. Tetrameric transthyretin structure stabilisators are in development.