Familial amyloidotic polyneuropathy type 1 in Brazil is associated with the transthyretin Val30Met variant

C1QA and C1QC modify age-at-onset in familial amyloid polyneuropathy patients

Objectives

Transthyretin (TTR) familial amyloid polyneuropathy (FAP) (OMIM 176300) shows a variable age‐at‐onset (AO), including within families. We hypothesized that variants in C1QA and C1QC genes, might also act as genetic modifiers of AO in TTR‐FAP Val30Met Portuguese patients.

Methods

We analyzed DNA samples of 267 patients (117 families). To search for variants, all exons and flanking regions were genotyped by automated sequencing. We used generalized estimating equations (GEEs) to take into account the non‐independency of AO among relatives. Intensive in silico analyses were performed, using various software to assess miRNAs target sites, splicing sites, transcription factor binding sites alterations, and gene–gene interactions.

Results

Two variants for C1QA gene, GA genotype of rs201693493 (P < 0.001) and CT genotype of rs149050968 (P < 0.001), were significantly associated with later AO. In silico analysis demonstrated, that rs201693493 may alter splicing activity. Regarding C1QC, we found three statistically significant results: GA genotype of rs2935537 (P = 0.003), GA genotype of rs201241346 (P < 0.001) and GA genotype of rs200952686 (P < 0.001). The first two were associated with earlier AO, whereas the third was associated with later‐onset.

Interpretation

C1QA was associated with later onset, whereas C1QC may have a double role: variants may confer earlier or later AO. As found in a study in Cyprus, we confirmed the role of complement C1Q genes (and thus of inflammation) as modulator of AO in Portuguese patients with TTR‐FAP Val30Met.

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).

Transthyretin proteins regulate angiogenesis by conferring different molecular identities to endothelial cells

Familial amyloidotic polyneuropathy (FAP) has a high prevalence in Portugal, and the most common form of hereditary amyloidosis is caused by an amyloidogenic variant of transthyretin (TTR) with a substitution of methionine for valine at position 30 (V30M). Until now, the available efficient therapy is liver transplantation, when performed in an early phase of the onset of the disease symptoms. However, transplanted FAP patients have a significantly higher incidence of early hepatic artery thrombosis compared with non-FAP transplanted patients. Because FAP was described as an independent risk factor for early hepatic artery thrombosis, more studies to understand the underlying mechanisms involved in this outcome are of the utmost importance. Knowing that the liver is the major site for TTR production, we investigated the biological effects of TTR proteins in the vasculature and on angiogenesis. In this study, we identified genes differentially expressed in endothelial cells exposed to the WT or V30M tetramer. We found that endothelial cells may acquire different molecular identities when exposed to these proteins, and consequently TTR could regulate angiogenesis. Moreover, we show that V30M decreases endothelial survival by inducing apoptosis, and it inhibits migration. These findings provide new knowledge that may have critical implications in the prevention of early hepatic artery thrombosis in FAP patients after liver transplantation.

Fibrinogen A alpha-chain amyloidosis: report of the first case in Latin America

BACKGROUND

Hereditary fibrinogen A alpha-chain (AFib) amyloidosis affects different organs, especially the kidneys. No case of this disease has been reported in Latin America.

CASE REPORT

A 52-year-old previously healthy Brazilian woman presented with a seven-month history of proteinuria in the absence of hematuria. The patient had normal blood pressure and reported no other symptoms. A renal biopsy was obtained and light microscopy revealed the presence of Congo red positive deposits (apple-green birefringence under polarized light) only in the glomerular compartment. These deposits were strongly immunoreactive to fibrinogen in all glomeruli. Electron microscopy showed the presence of organized deposits compatible with AFib. The diagnosis was confirmed by DNA analysis of the AFib gene, which demonstrated a Glu526Val mutation in one allele.

CONCLUSION

This first description of hereditary AFib amyloidosis in Latin America highlights the need to include this type of amyloidosis in the differential diagnosis, especially in Brazil where the degree of miscegenation is high.

Spatial visual contrast sensitivity in liver transplanted Portuguese familial amyloidotic polyneuropathy (ATTR V30M) patients

Liver transplanted patients with familial amyloidosis (FAP) patients develop earlier presbyopia due to the deposition of amyloid on the anterior capsule of the lens. Despite normal visual acuity of 20/20 Snellen chart, some patients reported complaints of impaired vision. The aim of this study is to investigate the visual spatial contrast sensitivity in these patients. This is a retrospective, nonrandomized study. Spatial contrast sensitivity was performed in both eyes of 25 FAP patients with best correct visual acuity of 20/20 Snellen chart. In each patient, one eye had visible opacification of anterior capsule of the lens. FAP patients had poorer visual contrast sensitivity than normal even in absence of visible opacification of the anterior capsule of the lens. Comparing eyes with visible opacification of anterior capsule of the lens with eyes without visible opacification of the anterior capsule of the lens, a worse visual sensitivity was observed at all frequencies tested. This occurred with similar lacrimal function in both groups. The eyes of FAP patients have decreased spatial contrast sensitivity which is worse in presence of visible opacification of the anterior capsule of the lens. This could explain the visual complaints in presence of normal visual acuity by Snellen chart.

Familial amyloidosis in a large Spanish kindred resulting from a D38V mutation in the transthyretin gene

BACKGROUND

Transthyretin amyloidosis, also known as familial amyloidotic polyneuropathy, is an autosomal dominant disorder that results from a mutation in the gene encoding plasma transthyretin (TTR). Distinct clinical presentations of the disease have been related so far to different point mutations, polyneuropathy being the predominant clinical feature in the majority of cases. Nevertheless, misdiagnosis of familial forms of amyloidosis is still common.

MATERIALS AND METHODS

A 71-year-old man was admitted to our hospital for heart failure. He had been previously diagnosed of AL amyloidosis with predominant polyneuropathic, cardiac and laryngeal involvement on the basis of clinical data and amyloid deposition in tissue specimens. During admission, suspicion of transthyretin amyloidosis was raised due to the absence of renal involvement, monoclonal protein and plasma cell dyscrasia. Complete clinical evaluation and sequence analysis of the TTR gene of the patient and his family were performed.

RESULTS

Gene sequence analysis revealed a rare A-to-T transition in exon 2 resulting in the substitution of aspartic acid by valine at position 38 (D38V) in the index case and in two other members of the family. Clinical study of the kindred showed a predominant late-onset heart involvement with variable polyneuropathy.

CONCLUSIONS

Here we report a large pedigree from Spain with three members affected by a severe late-onset form of amyloidosis due to a rare D38V TTR mutation. The variations on the natural history of this form of amyloidosis may have important consequences on genetic counselling, follow-up, and therapeutic approaches for these patients.

A novel type of familial transthyretin amyloidosis, ATTR Asn124Ser, with co-localization of kappa light chains

A 68-year-old Italian woman who had a clinical history of thyroidectomy in 2002 presented with slowly progressing renal insufficiency and non-nephrotic proteinurea in 2004. A renal biopsy showed the occurrence of amyloid; the thyroid biopsy previously taken also revealed amyloid infiltration. Other amyloid-containing tissues included bone marrow and heart. The plasma cell level in the bone marrow was found to be less than 5% and both serum and urine samples were positive for a monoclonal kappa light chain band. DNA analysis unexpectedly revealed the presence of a novel transthyretin (TTR) mutation, ATTR Asn124Ser. Histologically, amyloid deposits in the thyroid had a homogeneous appearance with moderate Congophilia. In immunohistochemistry, a kappa light chain antiserum showed positive immunoreactivity with amyloid deposits in the thyroid. Furthermore, a TTR antiserum, anti-TTR50-127, also recognized a number of amyloid deposits stained positive with the kappa light chain antiserum. Overall, the kappa light chain antiserum reacted with most of the amyloid deposits in the thyroid, whereas TTR immunoreactivity was scarcer, with a scattered appearance. In contrast, only the anti-TTR50-127 antiserum labeled amyloid in the kidney, albeit not all deposits. In this study, we report a patient having a novel TTR variant, ATTR Asn124Ser, with co-localization of kappa light chains in the amyloid deposits in the thyroid tissue.

Transthyretin and familial amyloidotic polyneuropathy

Familial amyloidotic polyneuropathy (FAP) is an inherited autosomal dominant disease that is commonly caused by accumulation of deposits of transthyretin (TTR) amyloid around peripheral nerves. The only effective treatment for FAP is liver transplantation. However, recent studies on TTR aggregation provide clues to the mechanism of the molecular pathogenesis of FAP and suggest new avenues for therapeutic intervention. It is increasingly recognized that there are common features of a number of protein-misfolding diseases that can lead to neurodegeneration. As for other amyloidogenic proteins, the most toxic forms of aggregated TTR are likely to be the low-molecular-mass diffusible species, and there is increasing evidence that this toxicity is mediated by disturbances in calcium homeostasis. This article reviews what is already known about the mechanism of TTR aggregation in FAP and describes how recent discoveries in other areas of amyloid research, particularly Alzheimer's disease, provide clues to the molecular pathogenesis of FAP.

Phenotypic expression of familial amyloid polyneuropathy in Brazil

Familial amyloid polyneuropathy (FAP) is an inherited amyloidosis mainly associated with transthyretin Val30Met variant. Clinical heterogeneity has been reported in different populations with FAP and Va130Met variant. In order to characterize FAP expression in Brazilians and to compare its features to those reported in other cohorts, 44 Brazilian patients (27 females, median age 36 [23-53] years) with FAP and the Val30Met variant were investigated. Approximately 40% of their family members, with the exception, of parents and siblings, had FAP. Most of the patients had symptoms of peripheral neuropathy at onset. Median age at onset was 32 [20-44] years. Earlier onset was observed in males (27 [20-43] years in males vs. 33 [20-44] years in females, P = 0.02) and in patients whose parents had FAP (31 [20-44] years vs. 40 [37-43] years in patients, respectively with and without affected parents, P = 0.03). Phenotypic expression of FAP in Brazil is similar to the one reported in Portugal, characterized by high disease penetrance, early onset, particularly in males and in subjects with affected parents, and major symptoms of peripheral neuropathy. These data highlight the influence of common genetic factors, shared by both groups of patients, in disease expression.

Outcome of liver transplantation for familial amyloidotic polyneuropathy

Familial amyloidotic polyneuropathy (FAP) is an autosomal dominant disorder caused by mutation in the transthyretin gene. The most common mutation is substitution of valine for methionine at position 30 (MET30). Liver transplantation (LT) is the preferred treatment. After LT, although many patients show stabilization or improvement in the disease, adverse outcomes have been reported in those who have malnutrition, long-standing disease, and non-MET (NMET) mutations at position 30. Our aim is to compare survival and outcome of symptoms associated with FAP after LT in patients with MET30 and NMET30 mutations. Medical records of all patients who underwent LT for amyloidosis at our institution were reviewed to obtain demographic information and clinical features, such as severity of neuropathy, diarrhea, orthostatic hypotension, and posterior wall or ventricle septal thickness before and after LT. Fifteen patients underwent LT for amyloidosis at our institution between 1990 and 2000 (MET30, n = 5; NMET30, n = 7; hereditary amyloidosis, n = 2; primary amyloidosis, AL type, n = 1). Patients with hereditary and primary amyloidosis were excluded from analysis. One- and 3-year survival rates after LT in MET30 patients were 100%. Before LT, five of five patients had sensorimotor neuropathy; five of five patients had diarrhea, and four of five patients had orthostatic hypotension. After LT, improvement or stabilization of neuropathy was seen in two of five patients; of diarrheal symptoms, in three of five patients; and of orthostatic hypotension, in three of four patients. One- and 3-year survival rates after LT in NMET30 patients were 100% and 85.7%, respectively. Before LT, six of seven patients had sensorimotor neuropathy, six of seven patients had diarrhea, and five of seven patients had orthostatic hypotension. After LT in this group, improvement or stabilization of neuropathy was seen in two of six patients; of diarrhea, in six of six patients; and of orthostatic hypotension, in five of five patients. Before LT, posterior wall and/or ventricle septal thickness was increased in two of five MET patients and seven of seven NMET patients. Five of seven NMET30 patients (71.4%) who received a combined liver and heart transplant had stabilization, and two patients in the NMET group and one patient in the MET group had progression of heart disease. Outcomes for LT for patients with FAP with MET or NMET mutations were similar. Earlier LT for patients with FAP with MET30 or NMET30 mutation would improve outcomes after LT.

Hereditary transthyretin amyloidosis from a Scandinavian perspective

Hereditary transthyretin (TTR) amyloidosis is a rare often fatal form of systemic amyloidosis, that until recently was considered intractable, with the patients dying from the disease 5-15 years after onset. The phenotype of the disease varies according to the type of mutation, but generally the heart and/or the nervous system is affected. Liver and in some cases heart transplantation has now been shown to stop the progress of the disease, but the outcome depends on the patients' status at the time of operation, as no substantial improvement of the patients' symptoms has been noted after the procedure. Thus an early diagnosis is of importance for the outcome. In the following, we summarize our knowledge of the amyloidogenic TTR mutations found in the Scandinavian countries, their symptoms, how to settle the diagnosis and the outcome of transplantation. Besides, the problems arising from our capability to genetically test asymptomatic members of affected families for the trait will be discussed.

No evidence of de novo amyloidosis in recipients of domino liver transplantation: 12 to 40 (mean 24) month follow-up

Domino liver transplantation (DLT) has been performed for selected recipients at several centers, but de novo amyloidosis in recipients of livers from patients with familial amyloid polyneuropathy (FAP) remains a serious concern.

AIM

To evaluate the occurrence of de novo amyloidosis in recipients of DLT.

PATIENTS AND METHODS

Seven recipients of FAP livers were followed for clinical and electroneuromyographic signs of FAP and also for de novo amyloid deposition in the gut.

RESULTS

No signs and symptoms of de novo FAP nor any evidence of amyloid deposits in the gut were observed in recipients of DLT after a mean follow-up of 24 [12-40] months.

CONCLUSIONS

Signs and symptoms of FAP do not occur early in recipients of DLT. These livers could therefore be offered to patients suitable for conventional LT, particularly older subjects in whom the event of de novo amyloidosis would seem improbable.

Results of liver transplantation for familial amyloid polyneuropathy type I in Brazil

Familial amyloid polyneuropathy type I (FAP-I) is an inherited amyloidosis secondary to systemic deposition of amyloid fibrils containing mutant transthyretin (TTR) variants. The disease has a progressive clinical course and is usually fatal 10 years after its onset. TTR is mainly produced in hepatocytes, and liver transplantation (LT) has been proposed as an effective treatment for FAP-I. The aim of this study is to evaluate the results of LT for FAP-I in Brazil and analyze prognostic factors associated with survival after surgery. Twenty-four patients (median age, 36 years; range, 25 to 52 years) who underwent LT with the diagnosis of FAP-I were evaluated. Surgery was uneventful in all but six patients who died of complications of primary liver nonfunction (n = 1), cardiogenic shock (n = 1), sepsis (n = 3), and hepatic artery thrombosis (n = 3). Overall 1- and 5-year survival rates were 70% and 58%, respectively. Most patients had stabilization or improvement of symptoms after a median follow-up of 36 months (range, 14 to 82 months). Survivors had a shorter disease duration before LT (median, 6 years; range, 2 to 17 years v 9 years; range, 7 to 12 years; P =.02), greater albumin levels (median, 4 g/dL; range, 3 to 4.7 g/dL v 3.6 g/dL; range, 2.6 to 4.1 g/dL; P =.03), and greater modified body mass index scores (median, 735; range, 502 to 1,432 v 659; range, 411 to 803; P =.04) compared with nonsurvivors. However, only disease duration and albumin levels were independently associated with survival in multivariate analysis. In conclusion, LT is an effective therapy for FAP-I. Mortality after surgery is associated with poor nutritional status and long-standing disease before LT. Thus, LT should be performed as early as possible after the onset of FAP-I symptoms to avoid major disability and improve survival.