Hearing problems in patients with hereditary gelsolin amyloidosis

BACKGROUND

Gelsolin amyloidosis (AGel amyloidosis) is a hereditary form of systemic amyloidosis featuring ophthalmological, neurological and cutaneous symptoms. Previous studies based mainly on patients' self-reporting have indicated that hearing impairment might also be related to the disease, considering the progressive cranial neuropathy characteristic for AGel amyloidosis. In order to deepen the knowledge of possible AGel amyloidosis-related hearing problems, a clinical study consisting of the Speech, Spatial and Qualities of Hearing Scale (SSQ) questionnaire, clinical examination, automated pure-tone audiometry and a speech-in-noise test was designed.

RESULTS

Of the total 46 patients included in the study, eighteen (39%) had self-reported hearing loss. The mean scores in the SSQ were 8.2, 8.3 and 8.6 for the Speech, Spatial and Qualities subscales, respectively. In audiometry, the mean pure tone average (PTA) was 17.1 (SD 12.2) and 17.1 (SD 12.3) dB HL for the right and left ears, respectively, with no difference to gender- and age-matched, otologically normal reference values. The average speech reception threshold in noise (SRT) was - 8.2 (SD 1.5) and - 8.0 (SD 1.7) dB SNR for the right and left ears, respectively, which did not differ from a control group with a comparable range in PTA thresholds.

CONCLUSION

Although a significant proportion of AGel amyloidosis patients experience subjective difficulties in hearing there seems to be no peripheral or central hearing impairment at least in patients up to the age of 60 years.

Cardiac manifestations in Finnish gelsolin amyloidosis patients

INTRODUCTION

Finnish gelsolin amyloidosis (AGel amyloidosis) is an inherited systemic amyloidosis with well-known ophthalmological, neurological and cutaneous symptoms. Additionally, cardiomyopathies, conduction disorders and need of cardiac pacemakers occur in some patients. This study focuses on electrocardiographic (ECG) findings in AGel amyloidosis and their relation to cardiac magnetic resonance (CMR) changes. We also assessed whether ECG abnormalities were associated with pacemaker implantation and mortality.

MATERIALS AND METHODS

In this cohort study, 51 genetically verified AGel amyloidosis patients (mean age 66 years) without cardiac pacemakers underwent 12-lead ECG and CMR imaging with contrast agent in 2017. Patients were followed-up for 3 years.

RESULTS

Conduction disturbances were found in 22 patients (43%). Nine (18%) presented with first-degree atrioventricular block, six (12%) with left anterior hemiblock, seven (14%) with left or right bundle branch block and two (4%) with non-specific intraventricular conduction delay. Low QRS voltage was present in two (4%) patients. Late gadolinium enhancement (LGE) concentrating on the interventricular septum and inferior parts of the heart was present in 19 (86%) patients with conduction abnormalities. During the follow-up, only one patient received a pacemaker, and one patient died.

DISCUSSION

Conduction disorders and septal LGE are common in AGel amyloidosis, whereas other ECG and CMR findings typically observed in most common cardiac amyloidosis types were rare. Septal pathology seen in CMR may interfere with the cardiac conduction system in AGel amyloidosis, explaining conduction disorders, although pacemaker therapy is rarely required.

Severe elastolysis in hereditary gelsolin (AGel) amyloidosis

AGel amyloidosis is a dominantly inherited systemic amyloidosis caused by mutations p.D214N or p.D214Y resulting in gelsolin amyloid (AGel) formation. AGel accumulates extracellularly in many tissues and alongside elastic fibres. AGel deposition associates with elastic fibre degradation leading to severe clinical manifestations, such as cutis laxa and angiopathic complications. We analysed elastic fibre pathology in dermal and vascular tissue and plasma samples from 35 patients with AGel amyloidosis and 40 control subjects by transmission electron microscopy, immunohistochemistry and ELISA methods. To clarify the pathomechanism(s) of AGel-related elastolysis, we studied the roles of MMP-2, -7, -9, -12 and -14, TIMP-1 and TGFβ. We found massive accumulation of amyloid fibrils along elastic fibres as well as fragmentation and loss of elastic fibres in all dermal and vascular samples of AGel patients. Fibrils of distinct types formed fibrous matrix. The degradation pattern of elastic fibres in AGel patients was different from the age-related degradation in controls. The elastin of elastic fibres in AGel patients was strongly decreased compared to controls. MMP-9 was expressed at lower and TGFβ at higher levels in AGel patients than in controls. The accumulation of amyloid fibrils with severe elastolysis characterises both dermal and vascular derangement in AGel amyloidosis.

Finnish gelsolin amyloidosis causes significant disease burden but does not affect survival: FIN-GAR phase II study

BACKGROUND

Hereditary gelsolin (AGel) amyloidosis is an autosomal dominantly inherited systemic amyloidosis that manifests with the characteristic triad of progressive ophthalmological, neurological and dermatological signs and symptoms. The National Finnish Gelsolin Amyloidosis Registry (FIN-GAR) was founded in 2013 to collect clinical data on patients with AGel amyloidosis, including altogether approximately one third of the Finnish patients. We aim to deepen knowledge on the disease burden and life span of the patients using data from the updated FIN-GAR registry. We sent an updated questionnaire concerning the symptoms and signs, symptomatic treatments and subjective perception on disease progression to 240 members of the Finnish Amyloidosis Association (SAMY). We analyzed the lifespan of 478 patients using the relative survival (RS) framework.

RESULTS

The updated FIN-GAR registry includes 261 patients. Symptoms and signs corresponding to the classical triad of ophthalmological (dry eyes in 93%; corneal lattice amyloidosis in 89%), neurological (numbness, tingling and other paresthesias in 75%; facial paresis in 67%), and dermatological (drooping eyelids in 86%; cutis laxa in 84%) manifestations were highly prevalent. Cardiac arrhythmias were reported by 15% of the patients and 5% had a cardiac pacemaker installed. Proteinuria was reported by 13% and renal failure by 5% of the patients. A total of 65% of the patients had undergone a skin or soft tissue surgery, 26% carpal tunnel surgery and 24% at least unilateral cataract surgery. As regards life span, relative survival estimates exceeded 1 for males and females until the age group of 70-74 years, for which it was 0.96.

CONCLUSIONS

AGel amyloidosis causes a wide variety of ophthalmological, neurological, cutaneous, and oral symptoms that together with repeated surgeries cause a clinically significant disease burden. Severe renal and cardiac manifestations are rare as compared to other systemic amyloidoses, explaining in part the finding that AGel amyloidosis does not shorten the life span of the patients at least for the first 75 years.

Amyloid in parenchymal organs in gelsolin (AGel) amyloidosis

Objectives: Previous clinical studies have shown frequent cardiac symptoms in patients with hereditary gelsolin (AGel) amyloidosis, possibly related to amyloid deposition in the heart and other internal organs. Previous studies on internal organ amyloid deposition in AGel amyloidosis have been based on small patient series. Methods: Paraffin-embedded tissue sections from 25 autopsied individuals (age at death 44.4-88.6 years) with AGel amyloidosis were stained with HE, Congo red and Herovici stains and immunohistochemistry against the low molecular weight gelsolin fraction was performed. The amount of amyloid was estimated semi-quantitatively. Results: AGel-based amyloid deposits were found in the myocardium and cardiac blood vessels in every patient. The deposits were mainly small and co-localized with regions with excess fibrosis in the myocardium. The lungs were positive for amyloid in 79%, renal parenchyma in 54% and renal blood vessels in 71% of the cases. The amount of myocardial, renal and hepatic amyloid correlated with age at death of the patients. Conclusions: We show the constant presence of AGel amyloid in the hearts of patients with AGel amyloidosis. Although the deposits were mainly small, the co-localization of amyloid with fibrosis may amplify the effect of pure amyloid deposition, possibly leading to clinical signs and symptoms.

Common origin of the gelsolin gene variant in 62 Finnish AGel amyloidosis families

Finnish gelsolin amyloidosis (AGel amyloidosis) is an autosomal dominantly inherited systemic disorder with ophthalmologic, neurologic and dermatologic symptoms. Only the gelsolin (GSN) c.640G>A variant has been found in the Finnish patients thus far. The purpose of this study was to examine whether the Finnish patients have a common ancestor or whether multiple mutation events have occurred at c.640G, which is a known mutational hot spot. A total of 79 Finnish AGel amyloidosis families including 707 patients were first discovered by means of patient interviews, genealogic studies and civil and parish registers. From each family 1-2 index patients were chosen. Blood samples were available from 71 index patients representing 64 families. After quality control, SNP array genotype data were available from 68 patients from 62 nuclear families. All the index patients had the same c.640G>A variant (rs121909715). Genotyping was performed using the Illumina CoreExome SNP array. The homozygosity haplotype method was used to analyse shared haplotypes. Haplotype analysis identified a shared haplotype, common to all studied patients. This shared haplotype included 17 markers and was 361 kb in length (GRCh37 coordinates 9:124003326-124364349) and this level of haplotype sharing was found to occur highly unlikely by chance. This GSN haplotype ranked as the largest shared haplotype in the 68 patients in a genome-wide analysis of haplotype block lengths. These results provide strong evidence that although there is a known mutational hot spot at GSN c.640G, all of the studied 62 Finnish AGel amyloidosis families are genetically linked to a common ancestor.

Increasing amount of amyloid are associated with the severity of clinical features in hereditary gelsolin (AGel) amyloidosis

BACKGROUND

Patients with hereditary gelsolin (AGel) amyloidosis (HGA) present with hanging skin (cutis laxa) and bilateral cranial neuropathy, and require symptomatic plastic surgery. Our clinical observation of tissue fragility prompted us to design a prospective study.

METHODS

Twenty-nine patients with HGA undergoing surgery were interviewed and clinically examined. The height and thickness of skin folds in standard anatomical localizations were measured. The presence and distribution of amyloid in skin samples were analyzed using Congo red staining and immunohistochemistry using antibodies against gelsolin amyloid (AGel) subunit.

RESULTS

The measured skin folds stretched more in patients with HGA (e.g. skin over olecranon, p < 0.001). The skin folds were thinner in patients with HGA (e.g. forehead skin, p < 0.001). The skin and subcutaneous fat were abnormally fragile during surgery. The total amount of AGel amyloid, and its presence in the deep layers of the skin and subcutaneous fat correlated with the measurements of skin folds, age and extent of cranial neuropathy.

CONCLUSIONS

The AGel amyloid in the skin and subcutis, together with morphologic changes in the dermal stroma and skin adnexa contribute to the atrophied and fragile structure of HGA skin. This is the first study to demonstrate the correlation between AGel amyloid accumulation and clinical disease severity.

Causes of death and life span in Finnish gelsolin amyloidosis

BACKGROUND

Finnish type of hereditary gelsolin amyloidosis (AGel amyloidosis) is an autosomal dominant disorder. Until recently, there has only been little knowledge of fatal complications of the disease and its possible impact on the patients' life span.

METHODS

We identified 272 deceased patients based on patient interviews and genealogical data. After collecting their death certificates, we recorded the patients' underlying and immediate causes of death (CoD) and life span and compared them to the general Finnish population. We then calculated proportional mortality ratios (PMR), standardised for age and sex, for the CoDs.

RESULTS

The underlying CoD in 20% of the patients was AGel amyloidosis (PMR = 114.2; 95% CI: 85.6-149.4). The frequency of fatal cancers (10%) was significantly diminished (PMR = 0.47; 95% CI: 0.31-0.69). Renal complications were overrepresented as the immediate CoD in female patients (PMR = 2.82 95% CI: 1.13-5.81). The mean life span for male patients was 73.9 years (95% CI: 72.0-75.6) and 78.0 years for female patients (95% CI: 76.4-79.5) compared to 72.1 and 80.1 years for the general population.

CONCLUSIONS

Our results suggest that the disease increases the risk of fatal renal complications but does not substantially shorten the life span, possibly due to the significantly lower frequency of fatal cancers. Key Messages AGel amyloidosis may increase the risk of renal complications, especially among female patients. The frequency of fatal cancers is significantly lower. The patients' life span is comparable to that of the general population.

Gelsolin amyloid angiopathy causes severe disruption of the arterial wall

Hereditary gelsolin amyloidosis (HGA) is a dominantly inherited systemic disease reported worldwide. HGA is characterized by ophthalmological, neurological, and dermatological manifestations. AGel amyloid accumulates at basal lamina of epithelial and muscle cells, thus amyloid angiopathy is encountered in nearly every organ. HGA patients have cardiovascular, hemorrhagic, and potentially vascularly induced neurological problems. To clarify pathomechanisms of AGel angiopathy, we performed histological, immunohistochemical, and electron microscopic analyses on facial temporal artery branches from 8 HGA patients and 13 control subjects. We demonstrate major pathological changes in arteries: disruption of the tunica media, disorganization of vascular smooth muscle cells, and accumulation of AGel fibrils in arterial walls, where they associate with the lamina elastica interna, which becomes fragmented and diminished. We also provide evidence of abnormal accumulation and localization of collagen types I and III and an increase of collagen type I degradation product in the tunica media. Vascular smooth muscle cells appear to be morphologically and semi-quantitatively normal, only their basal lamina is often thickened. In conclusion, angiopathy in HGA results in severe disruption of arterial walls, characterized by prominent AGel deposition, collagen derangement and severe elastolysis, and it may be responsible for several, particularly hemorrhagic, disease manifestations in HGA.

Mutations in DNMT3B Modify Epigenetic Repression of the D4Z4 Repeat and the Penetrance of Facioscapulohumeral Dystrophy

Facioscapulohumeral dystrophy (FSHD) is associated with somatic chromatin relaxation of the D4Z4 repeat array and derepression of the D4Z4-encoded DUX4 retrogene coding for a germline transcription factor. Somatic DUX4 derepression is caused either by a 1-10 unit repeat-array contraction (FSHD1) or by mutations in SMCHD1, which encodes a chromatin repressor that binds to D4Z4 (FSHD2). Here, we show that heterozygous mutations in DNA methyltransferase 3B (DNMT3B) are a likely cause of D4Z4 derepression associated with low levels of DUX4 expression from the D4Z4 repeat and increased penetrance of FSHD. Recessive mutations in DNMT3B were previously shown to cause immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome. This study suggests that transcription of DUX4 in somatic cells is modified by variations in its epigenetic state and provides a basis for understanding the reduced penetrance of FSHD within families.

Intrafamilial clinical variability in individuals carrying the CHCHD10 mutation Gly66Val

OBJECTIVES

Mutations in the CHCHD10 gene, which encodes a mitochondrially targeted protein, have emerged as an important cause of motor neuron disease and frontotemporal lobar degeneration. The aim of this study was to assess the clinical variability in a large family carrying the p.Gly66Val mutation of the CHCHD10 gene. This mutation has recently been reported to cause late-onset spinal muscular atrophy (SMAJ) or sensorimotor axonal Charcot-Marie-Tooth neuropathy (CMT2) in the Finnish population.

MATERIALS AND METHODS

Nine affected members of an extended Finnish pedigree were included in the study. Detailed clinical and neurophysiological examinations were performed. The CHCHD10 p.Gly66Val mutation was examined by Sanger sequencing.

RESULTS

The heterozygous p.Gly66Val mutation was present in all affected individuals from whom a DNA sample was available. The clinical phenotype varied from proximal sensorimotor neuropathy to spinal muscular atrophy and in one case resembled motor neuron disease ALS at its early stages. The age of onset varied from 30 to 73 years.

CONCLUSIONS

Our data demonstrate that even within the same family, the p.Gly66Val variant can cause variable phenotypes ranging from CMT2-type axonal neuropathy to spinal muscular atrophy, which may also present as an ALS-like disease. The spectrum of CHCHD10-related neuromuscular disease has widened rapidly, and we recommend keeping the threshold for genetic testing low particularly when dominant inheritance or mitochondrial pathology is present.

Progressive cranial nerve involvement and grading of facial paralysis in gelsolin amyloidosis

INTRODUCTION

Hereditary gelsolin amyloidosis (GA) is a rare condition caused by the gelsolin gene mutation. The diagnostic triad includes corneal lattice dystrophy (type 2), progressive bilateral facial paralysis, and cutis laxa. Detailed information on facial paralysis in GA and the extent of cranial nerve injury is lacking.

METHODS

29 GA patients undergoing facial corrective surgery were interviewed, examined, and studied electroneurophysiologically.

RESULTS

All showed dysfunction of facial (VII) and trigeminal (V) nerves, two-thirds of oculomotor (III) and hypoglossal (XII) nerves, and half of vestibulocochlear (acoustic) (VIII) nerve. Clinical involvement of frontal, zygomatic, and buccal facial nerve branches was seen in 97%, 83%, and 52% of patients, respectively. Electromyography showed marked motor unit potential loss in facial musculature.

CONCLUSIONS

Cranial nerve involvement in GA is more widespread than previously described, and correlates with age, severity of facial paralysis, and electromyographic findings. We describe a grading method for bilateral facial paralysis in GA, which is essential for evaluation of disease progression and the need for treatment.

Gender differences in the clinical course of Finnish gelsolin amyloidosis

PURPOSE

To investigate gender differences in Finnish gelsolin amyloidosis (AGel amyloidosis).

PATIENTS AND METHODS

AGel amyloidosis patients, who were members of Finnish Amyloidosis Association (SAMY), filled in a questionnaire compiling known and suspected aspects of their disease. Telephone interviews and hospital medical records, when available, complemented the questionnaire. The data were entered to the database in order to create a national AGel amyloidosis patient registry (FIN-GAR).

RESULTS

A total of 227 patients, 156 women and 71 men, participated in the study. The women in our registry noticed their first symptoms at the median age of 39 years versus 43 years for men (p = 0.01). At the age in which the diagnosis was made there was a trend to be observed between men and women (women: 39 years versus men: 43 years, p = 0.053). Corneal lattice dystrophy was diagnosed in significantly younger women than men (median ages 41 versus 49 years, respectively, p = 0.01). Of other ophthalmological manifestations, corneal ulcer, impaired vision and glaucoma were all diagnosed at least 5 years earlier in women, although differences were not statistically significant. Ophthalmological manifestations, such as dry eyes and corneal ulcer; dermatological signs, such as blepharochalasis, and also neurological symptoms, such as myokymia and carpal tunnel syndrome, were more prevalent among women.

CONCLUSIONS

In the largest so far available study on AGel amyloidosis we show that women developed symptoms and signs of AGel amyloidosis at younger age. Especially eye-related problems occurred earlier and together with nerve and skin manifestations, the characteristic clinical triad in AGel amyloidosis, were more common in women. However, a clear limitation of our study was a selection bias caused by a significant underrepresentation of men in the study population.

A novel transthyretin Lys70Glu (p.Lys90Glu) mutation presenting with vitreous amyloidosis and carpal tunnel syndrome

OBJECTIVE

We describe a novel TTR mutation with vitreous opacities and carpal tunnel syndrome.

MATERIALS AND METHODS

A 78 year-old woman with vitreous opacities, her daughter with dry eye syndrome, and brother with carpal tunnel syndrome were tested for a mutation in the TTR gene. The vitreous opacities were removed and stained with Congo red and immunohistochemistry against wild type TTR. Skin and gut biopsies and specimens of soft tissue were examined histopathologically. Leukocyte DNA from the proband was analysed by direct sequencing of exons 1 to 4 of the TTR gene and DNA from her daughter and brother using segregation analysis.

RESULTS

A point mutation c.268 A>C, in the TTR gene, leading to a missense mutation p.Lys90Glu was found in all subjects. The vitreous opacities were pearl string-like. Histopathology showed red to green birefringence in Congo red, typical to amyloid, and the specimens were immunoreactive with antibodies against TTR.

CONCLUSION

We present a novel autosomally inherited Lys90Glu mutation in the TTR gene. This is the first reported FAP family with this mutation in Finland.

Novel mutations in DNAJB6 gene cause a very severe early-onset limb-girdle muscular dystrophy 1D disease

DNAJB6 is the causative gene for limb-girdle muscular dystrophy 1D (LGMD1D). Four different coding missense mutations, p.F89I, p.F93I, p.F93L, and p.P96R, have been reported in families from Europe, North America and Asia. The previously known mutations cause mainly adult-onset proximal muscle weakness with moderate progression and without respiratory involvement. A Finnish family and a British patient have been studied extensively due to a severe muscular dystrophy. The patients had childhood-onset LGMD, loss of ambulation in early adulthood and respiratory involvement; one patient died of respiratory failure aged 32. Two novel mutations, c.271T > A (p.F91I) and c.271T > C (p.F91L), in DNAJB6 were identified by whole exome sequencing as a cause of this severe form of LGMD1D. The results were confirmed by Sanger sequencing. The anti-aggregation effect of the mutant DNAJB6 was investigated in a filter-trap based system using transient transfection of mammalian cell lines and polyQ-huntingtin as a model for an aggregation-prone protein. Both novel mutant proteins show a significant loss of ability to prevent aggregation.

Hereditary renal amyloidosis caused by a heterozygous G654A gelsolin mutation: a report of two cases

Finnish-type familial amyloidosis (FAF) is a rare hereditary systemic amyloidosis that mainly exhibits cranial neuropathy. We describe a Japanese family with FAF manifested predominantly as renal amyloidosis. The proband was a 42-year-old woman with a 21-year history of proteinuria due to renal amyloidosis. Her mother was subsequently diagnosed with a similar disorder. After the first renal biopsy, both patients were followed up routinely for a period of 14 years. Genetic analysis of DNA samples revealed a heterozygous G654A gelsolin mutation. Severe renal involvement has not been reported previously in patients with FAF bearing a heterozygous gelsolin mutation.

CHCHD10 variant p.(Gly66Val) causes axonal Charcot-Marie-Tooth disease

OBJECTIVE

We describe the phenotype consistent with axonal Charcot-Marie-Tooth disease type 2 (CMT2) in 4 families with a c.197G>T (p.(Gly66Val)) variant in CHCHD10.

METHODS

We sequenced the CHCHD10 gene in a cohort of 107 families with CMT2 of unknown etiology. The patients were characterized by clinical examination and electroneuromyography. Muscle MRI and biopsy of the muscle or nerve were performed in selected cases. Neuropathologic autopsy was performed in 1 case.

RESULTS

The c.197G>T variant in CHCHD10 was found in 6 families, 4 of which included multiple individuals available for detailed clinical study. Variants in this gene have recently been associated with amyotrophic lateral sclerosis-frontotemporal dementia, mitochondrial myopathy, or spinal muscular atrophy Jokela type (SMAJ), but not with CMT2. Our patients had a late-onset distal axonal neuropathy with motor predominance, progressing to involve sensory nerves. Neurophysiologic and neuropathologic studies confirmed the diagnosis of sensorimotor axonal neuropathy with no loss of anterior horn neurons. Muscle biopsies showed occasional cytochrome c oxidase-negative fibers, combined with small amounts of mitochondrial DNA deletions.

CONCLUSIONS

CHCHD10 c.197G>T (p.(Gly66Val)) is a cause of sensorimotor axonal neuropathy. This gene should be considered in patients presenting with a pure CMT2 phenotype, particularly when motor symptoms predominate.

Natural course of Finnish gelsolin amyloidosis

BACKGROUND

Finnish type of hereditary gelsolin amyloidosis (FGA) is one of the most common diseases of Finnish disease heritage. Existing FGA knowledge is based only on smaller patient series, so our aim was to elucidate the natural course of the disease in a comprehensive sample of patients and to build up a national FGA patient registry.

METHODS

An inquiry about the known and suspected signs of FGA, sent to the members of Finnish Amyloidosis Association, telephone contacts, and hospital records were utilized to create the registry.

RESULTS

A total of 227 patients were entered to the database. The first symptom was ophthalmological for 167 patients (73.6%) at the mean age of 39 years. Corneal lattice dystrophy (CLD) was reported at the mean age of 43 years. Impaired vision, polyneuropathy, facial nerve paresis, and cutis laxa appeared on average between 52 and 57 years. Carpal tunnel syndrome (CTS) was reported by 86 patients (37.9%). Nine patients (4.0%) had a pacemaker, and 12 (6.1%) had cardiomyopathy.

CONCLUSIONS

The first symptom was ophthalmological in most cases. Except for CLD no prominent difference in the age of appearance was found between the major symptoms. CTS, cardiac pacemakers, and cardiomyopathy were remarkably more common compared to the general population.

Subtle neuropsychiatric and neurocognitive changes in hereditary gelsolin amyloidosis (AGel amyloidosis)

Hereditary gelsolin amyloidosis (AGel amyloidosis) is an autosomal dominant form of systemic amyloidosis caused by a c.640G>A or c.640G>T mutation in the gene coding for gelsolin. Principal clinical manifestations include corneal lattice dystrophy, cranial neuropathy and cutis laxa with vascular fragility. Signs of minor CNS involvement have also been observed, possibly related to cerebral amyloid angiopathy (CAA). To investigate further if AGel amyloidosis carries a risk for a specific neuropsychological or psychiatric symptomatology we studied 35 AGel patients and 29 control subjects. Neuropsychological tests showed abnormalities in visuocontructional and -spatial performance in AGel patients, also some indication of problems in processing efficacy was found. At psychiatric evaluation the patient group showed more psychiatric symptomatology, mainly depression. In brain MRI, available in 16 patients and 14 controls, we found microhemorrhages or microcalcifications only in the patient group, although the number of findings was small. Our study shows that AGel amyloidosis can be associated with visuoconstructional problems and depression, but severe neuropsychiatric involvement is not characteristic. The gelsolin mutation may even induce cerebrovascular fragility, but further epidemiological and histopathological as well as longitudinal follow-up studies are needed to clarify gelsolin-related vascular pathology and its clinical consequences.

Dominant GDAP1 founder mutation is a common cause of axonal Charcot-Marie-Tooth disease in Finland

We describe a founder mutation in the gene encoding ganglioside-induced differentiation associated-protein 1 (GDAP1), leading to amino acid change p.H123R, as a common cause of autosomal dominant axonal Charcot-Marie-Tooth (CMT2) neuropathy in Finland. The mutation explains up to 14 % of CMT2 in Finland, where most patients with axonal neuropathy have remained without molecular diagnosis. Only three families out of 28 were found to carry putative disease mutations in the MFN2 gene encoding mitofusin 2. In addition, the MFN2 variant p.V705I was commonly found in our patients, but we provide evidence that this previously described mutation is a common polymorphism and not pathogenic. GDAP1-associated polyneuropathy caused predominantly a mild and slowly progressive phenotype. Besides distal leg muscle weakness, most patients showed mild proximal weakness, often with asymmetry and pes cavus. Our findings broaden the understanding of GDAP1 mutations in CMT2 phenotypes and provide support for the use of whole-exome sequencing in CMT gene diagnostics.

Xerostomia in hereditary gelsolin amyloidosis

Hereditary gelsolin amyloidosis (AGel amyloidosis) is a rare, dominantly inherited systemic disease with worldwide distribution, caused by c.654G > A or c.654G > T gelsolin gene mutation. The disease mainly manifests with late-onset dystrophy of the cornea, laxity of the skin and dysfunction of the cranial nerves whereas the oral manifestations have remained less-studied. To examine if AGel amyloidosis also affects salivary gland function, we studied 27 patients. In a questionnaire, 89% of them reported oral dryness, and 74% oral and ocular dryness. Unstimulated (UWS) and stimulated whole salivary flow (SWS) rates were measured, and salivary proteins were analyzed in the patients and controls. Hyposalivation according to UWS was detected in 67% of the patients, while decreased SWS occurred in 63% of the patients and 19% of the controls (p = 0.001). The secretion rates of salivary total protein and IgA were significantly lower in patients than controls. Histopathological analyses of labial salivary gland biopsies showed deposition of gelsolin amyloid, atrophy and inflammation. This study showed that AGel amyloidosis belongs to the differential diagnostic choices to be kept in mind in the patients presenting with xerostomia, low secretion rates of salivary total protein and IgA and/or deposition of amyloid in the minor salivary glands. AGel amyloidosis patients should be advised for efficient dental care.

Hereditary gelsolin amyloidosis

Hereditary gelsolin amyloidosis (HGA) is an autosomally dominantly inherited form of systemic amyloidosis, characterized mainly by cranial and sensory peripheral neuropathy, corneal lattice dystrophy, and cutis laxa. HGA, originally reported from Finland and now increasingly from other countries in Europe, North and South America, and Asia, may still be underdiagnosed worldwide. It is the first and so-far only known disorder caused by a gelsolin gene defect, namely a G654A or G654T mutation. Gelsolin is a principal actin-modulating protein, implicated in multiple biological processes, also in the nervous system, e.g. axonal transport, myelination, neurite outgrowth, and neuroprotection. The gelsolin gene defect causes expression of variant gelsolin, followed by systemic deposition of gelsolin amyloid (AGel) in HGA patients and even other consequences on the metabolism and function of gelsolin. In HGA, specific therapy is not yet available but correct diagnosis enables adequate symptomatic treatment which decisively improves the quality of life in these patients. A transgenic murine model of HGA expressing AGel is available, in anticipation of new treatment options targeted toward this slowly progressive but devastating amyloidosis. Present and future lessons learned from HGA may be applicable even in diagnosis and treatment of other hereditary and sporadic amyloidoses.

Familial amyloidotic polyneuropathy type IV--gelsolin amyloidosis

Familial amyloidotic polyneuropathy type IV, or Gelsolin amyloidosis (GA), is a rare condition caused by G654A or G654T mutation in gelsolin gene at 9q32-34. Gelsolin seems essential in many processes, including inflammation, cell motility, neural recovery, apoptosis and even carcinogenesis. So far reported from many European countries, USA, Japan, Iran and Brazil, GA is probably still underdiagnosed. The typical diagnostic triad includes corneal lattice dystrophy, progressive bilateral facial paralysis and cutis laxa. Patients present with progressive cranial and peripheral neuropathy, eye symptoms, usually mild proteinuria, and cardiac conductive disturbances with age. Central nervous system symptoms are rare. Gelsolin amyloid collection in tissues is widespread. To date, treatment is symptomatic. Regular check-ups with ophthalmologist are recommended. Plastic surgery relieves the functional symptoms caused by facial paralysis and loose, hanging facial skin.

FGF-21 as a biomarker for muscle-manifesting mitochondrial respiratory chain deficiencies: a diagnostic study

BACKGROUND

Muscle biopsy is the gold standard for diagnosis of mitochondrial disorders because of the lack of sensitive biomarkers in serum. Fibroblast growth factor 21 (FGF-21) is a growth factor with regulatory roles in lipid metabolism and the starvation response, and concentrations are raised in skeletal muscle and serum in mice with mitochondrial respiratory chain deficiencies. We investigated in a retrospective diagnostic study whether FGF-21 could be a biomarker for human mitochondrial disorders.

METHODS

We assessed samples from adults and children with mitochondrial disorders or non-mitochondrial neurological disorders (disease controls) from seven study centres in Europe and the USA, and recruited healthy volunteers (healthy controls), matched for age where possible, from the same centres. We used ELISA to measure FGF-21 concentrations in serum or plasma samples (abnormal values were defined as >200 pg/mL). We compared these concentrations with values for lactate, pyruvate, lactate-to-pyruvate ratio, and creatine kinase in serum or plasma and calculated sensitivity, specificity, and positive and negative predictive values for all biomarkers.

FINDINGS

We analysed serum or plasma from 67 patients (41 adults and 26 children) with mitochondrial disorders, 34 disease controls (22 adults and 12 children), and 74 healthy controls. Mean FGF-21 concentrations in serum were 820 (SD 1151) pg/mL in adult and 1983 (1550) pg/mL in child patients with respiratory chain deficiencies and 76 (58) pg/mL in healthy controls. FGF-21 concentrations were high in patients with mitochondrial disorders affecting skeletal muscle but not in disease controls, including those with dystrophies. In patients with abnormal FGF-21 concentrations in serum, the odds ratio of having a muscle-manifesting mitochondrial disease was 132·0 (95% CI 38·7-450·3). For the identification of muscle-manifesting mitochondrial disease, the sensitivity was 92·3% (95% CI 81·5-97·9%) and specificity was 91·7% (84·8-96·1%). The positive and negative predictive values for FGF-21 were 84·2% (95% CI 72·1-92·5%) and 96·1 (90·4-98·9%). The accuracy of FGF-21 to correctly identify muscle-manifesting respiratory chain disorders was better than that for all conventional biomarkers. The area under the receiver-operating-characteristic curve for FGF-21 was 0·95; by comparison, the values for other biomarkers were 0·83 lactate (p=0·037, 0·83 for pyruvate (p=0·015), 0·72 for the lactate-to-pyruvate ratio (p=0·0002), and 0·77 for creatine kinase (p=0·013).

INTERPRETATION

Measurement of FGF-21 concentrations in serum identified primary muscle-manifesting respiratory chain deficiencies in adults and children and might be feasible as a first-line diagnostic test for these disorders to reduce the need for muscle biopsy.

FUNDING

Sigrid Jusélius Foundation, Jane and Aatos Erkko Foundation, Molecular Medicine Institute of Finland, University of Helsinki, Helsinki University Central Hospital, Academy of Finland, Novo Nordisk, Arvo and Lea Ylppö Foundation.

Clinical features of facioscapulohumeral muscular dystrophy 2

OBJECTIVE

In some 5% of patients with facioscapulohumeral muscular dystrophy (FSHD), no D4Z4 repeat contraction on chromosome 4q35 is observed. Such patients, termed patients with FSHD2, show loss of DNA methylation and heterochromatin markers at the D4Z4 repeat that are similar to patients with D4Z4 contractions (FSHD1). This commonality suggests that a change in D4Z4 chromatin structure unifies FSHD1 and FSHD2. The aim of our study was to critically evaluate the clinical features in patients with FSHD2 in order to establish whether these patients are phenotypically identical to FSHD1 and to establish the effects of the (epi-) genotype on the phenotype.

METHODS

This cross-sectional study studied 33 patients with FSHD2 from 27 families, the largest cohort described to date. All patients were clinically assessed using a standardized clinical evaluation form. Genotype analysis was performed by pulsed field gel electrophoresis and PCR; D4Z4 methylation was studied by methylation-sensitive Southern blot analysis.

RESULTS

FSHD2 is identical to FSHD1 in its clinical presentation. Notable differences include a higher incidence (67%) of sporadic cases and the absence of gender differences in disease severity in FSHD2. Overall, average disease severity in FSHD2 was similar to that reported in FSHD1 and was not influenced by D4Z4 repeat size. In FSHD2, a small effect of the degree of hypomethylation on disease severity was observed.

CONCLUSIONS

Clinically, patients with FSHD2 are indistinguishable from patients with FSHD1. The present data suggest that FSHD1 and FSHD2 are the result of the same pathophysiologic process.

A new distal myopathy with mutation in anoctamin 5

We have been following clinically and with muscle MRI for the past 3-decades a Finnish family with two patients with distal muscular dystrophy. Previously we demonstrated the cellular defect in these patients to be defective membrane repair and more recently have identified the causative gene to be anoctamin 5 (ANO5). The disorder seen in these patients is characterized by onset in the third decade. First symptoms were burning sensation on the calves and later on calf tightness during running. Muscle weakness and wasting were asymmetric and early involving the calf muscles, later spread to the thigh muscles. Biceps brachi was later manifestation. Clinical course was slow. CK levels were high. Muscle biopsy showed dystrophic pattern and multifocal disruption of the sarcolemmal membrane but no subsarcolemmal vesicle accumulation nor active inflammation. We conclude that the disease seen in our cases is a new separate clinical, genetic and histopathologic entity to include within the classification of autosomal recessive distal muscular dystrophies.

Investigation of AGE, their receptor and NF-kappaB activation and apoptosis in patients with ATTR and Gelsolin amyloidosis

BACKGROUND

Transthyretin (TTR) and gelsolin amyloidoses represent two types of hereditary amyloidosis in which point mutations in the respective protein lead to conformational changes of the protein with subsequent amyloid fibril formation.

MATERIAL AND METHODS

Tissues from Finnish gelsolin amyloid patients, Danish, Japanese and Swedish ATTR patients were immunostained for AGE, RAGE, NF-kappaB, PARP, and caspases 3 and 8.

RESULTS

Amyloid was heavily deposited in myocard, kidney and gastrointestinal tract of all patients. Immunoreactive areas to AGE and RAGE were detected in the heart, kidney, rectum, gut and appendix. AGE and RAGE were well co-localised with amyloid deposits. In five out of 14 patients neither NF-kappaB activation nor induction of apoptosis marked by positive immunostaining for NF-kappaB, PARP, or caspases 3 and 8 was found, and markers of apoptosis were detected in some samples without accompanying NF-kappaB activation.

CONCLUSION

Our results suggest that both AGE and RAGE may have a common role in evolution of TTR and gelsolin-related amyloidoses. Apart from AGE-RAGE interactions both amyloid proteins may directly bind to RAGE and result in cellular perturbations; but in view of this study cytotoxic effects other than those triggered by activation of NF-kappaB or apoptosis should be considered.

[Hereditary gelsolin amyloidosis--40 years of Meretoja disease]

Hereditary gelsolin amyloidosis is an autosomally dominantly inherited systemic disease, first described in 1969 by the Finnish ophthalmologist Jouko Meretoja. The estimated number of disease carriers in Finland is almost 1 000, and the disease has subsequently been found in many other countries as well. It's typical initial manifestation is lattice corneal dystrophy, detected at biomicroscopic examination of the eye by the age of 25 to 30 years, followed by slowly progressing cranial neuropathy with bilateral facial palsy, polyneuropathy and generalized cutis laxa. Meretoja's disease is caused by mutations of the gelsolin gene, leading to the production and aberrant processing of variant gelsolin and deposition of its fragments in various tissues in the form of amyloid fibrils.

Hereditary gelsolin amyloidosis mimicking Sjögren's syndrome

Hereditary gelsolin amyloidosis (AGel amyloidosis) belongs to the wide group of amyloidotic diseases, which comprise various hereditary but also sporadic forms, such as inflammation-associated AA amyloidosis, primary or myeloma-associated AL amyloidosis and common Alzheimer's disease and type II diabetes-associated local amyloidoses. AGel amyloidosis caused by a gelsolin G654A gene mutation is autosomally dominantly inherited and presents typically in the 30s with progressive corneal lattice dystrophy, followed by cutis laxa and cranial polyneuropathy. Here, we present a case of sicca syndrome, originally diagnosed as primary Sjögren's syndrome (SS) but later found to represent an initial disease manifestation of AGel amyloidosis, not recognised earlier. This case emphasises both the importance of specific amyloid stainings and comprehensive salivary gland histopathology as well as family history in SS differential diagnostics.

Severe ataxia with neuropathy in hereditary gelsolin amyloidosis

Hereditary gelsolin amyloidosis (AGel amyloidosis) is a systemic disorder caused by a G654A or G654T gelsolin mutation, reported from Europe, North America, and Japan. Principal clinical signs are corneal lattice dystrophy, cutis laxa and cranial neuropathy, often deleterious at advanced age. Peripheral neuropathy, if present, is usually mild. We report a 78- year old male Finnish patient who presented with ataxia and mainly sensory peripheral polyneuropathy (PNP) signs, causing severe disability and ambulation loss. Electrophysiological studies showed severe generalized chronic mainly axonal sensorimotor PNP with facial paralysis. In magnetic resonance imaging proximal lower limb and axial muscle atrophy with fatty degeneration as well as moderate spinal cord atrophy were seen. A G654A gelsolin mutation was demonstrated but no other possible causes of his disability were found. At age 79 he became bedridden and died of pulmonary embolism. Neuropathological examination revealed marked gelsolin amyloid deposition at vascular and connective tissue sites along the entire length of the peripheral nerves extending to the spinal nerve roots, associated with severe degeneration of nerve fibers and posterior columns. Our report shows that advanced AGel amyloidosis due to degeneration of central and distal sensory nerve projections results in deleterious ataxia with fatal outcome. Severe posterior column atrophy may reflect radicular AGel deposition, although even altered gelsolin - actin interactions in neural cells possibly contribute to neurodegeneration with successive ataxia in carriers of a G654A gelsolin mutation.

Senile systemic amyloidosis affects 25% of the very aged and associates with genetic variation in alpha2-macroglobulin and tau: a population-based autopsy study

BACKGROUND

Senile systemic amyloidosis (SSA) is characterized by deposition of wild-type transthyretin (TTR)-based amyloid in parenchymal organs in elderly individuals. Previously, no population-based studies have been performed on SSA.

METHODS

Here we have studied the prevalence and risk factors for SSA in a Finnish autopsied population aged 85 or over, as part of the population-based Vantaa 85+ Autopsy Study (n = 256). The diagnosis of SSA was based on histological examination of myocardial samples stained with Congo red and anti-TTR immunohistochemistry. The genotype frequencies of 20 polymorphisms in 9 genes in subjects with and without SSA were compared.

RESULTS

The prevalence of SSA was 25%. SSA was associated with age, myocardial infarctions, the G/G (Val/Val) genotype of the exon 24 polymorphism in the alpha2-macroglobulin (alpha2M), and the H2 haplotype of the tau gene (P-values 0.002, 0.004, 0.042, and 0.016).

CONCLUSION

This population-based study shows that SSA is very common in old individuals, affecting one-quarter of people aged over 85 years. Myocardial infarctions and variation in the genes for alpha2M and tau may be associated with SSA.

Severe ataxia with neuropathy in hereditary gelsolin amyloidosis: a case report

Hereditary gelsolin amyloidosis (AGel amyloidosis) is a systemic disorder caused by a G654A or G654T gelsolin mutation, reported from Europe, North America, and Japan. Principal clinical signs are corneal lattice dystrophy, cutis laxa and cranial neuropathy, often deleterious at advanced age. Peripheral neuropathy, if present, is usually mild. We report a 78-year-old male Finnish patient who presented with ataxia and mainly sensory peripheral polyneuropathy (PNP) signs, causing severe disability and ambulation loss. Electrophysiological studies showed severe generalized chronic mainly axonal sensorimotor PNP with facial paralysis. In magnetic resonance imaging proximal lower limb and axial muscle atrophy with fatty degeneration as well as moderate spinal cord atrophy were seen. A G654A gelsolin mutation was demonstrated but no other possible causes of his disability were found. At age 79 years he became bedridden and died of pulmonary embolism. Neuropathological examination revealed marked gelsolin amyloid deposition at vascular and connective tissue sites along the entire length of the peripheral nerves extending to the spinal nerve roots, associated with severe degeneration of nerve fibers and posterior columns. Our report shows that advanced AGel amyloidosis due to degeneration of central and distal sensory nerve projections results in deleterious ataxia with fatal outcome. Severe posterior column atrophy may reflect radicular AGel deposition, although even altered gelsolin-actin interactions in neural cells possibly contribute to neurodegeneration with successive ataxia in carriers of a G654A gelsolin mutation.

Patients with a non-dysferlin Miyoshi myopathy have a novel membrane repair defect

Two autosomal recessive muscle diseases, limb girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM), are caused by mutations in the dysferlin gene. These mutations result in poor ability to repair cell membrane damage, which is suggested to be the cause for this disease. However, many patients who share clinical features with MM-type muscular dystrophy do not carry mutations in dysferlin gene. To understand the basis of MM that is not due to mutations in dysferlin gene, we analyzed cells from patients in one such family. In these patients, we found no defects in several potential candidates - annexin A2, caveolin-3, myoferlin and the MMD2 locus on chromosome 10p. Similar to dysferlinopathy, these cells also exhibit membrane repair defects and the severity of the defect correlated with severity of their disease. However, unlike dysferlinopathy, none of the conventional membrane repair pathways are defective in these patient cells. These results add to the existing evidence that cell membrane repair defect may be responsible for MM-type muscular dystrophy and indicate that a previously unsuspected genetic lesion that affects cell membrane repair pathway is responsible for the disease in the non-dysferlin MM patients.

Senile systemic amyloidosis, cerebral amyloid angiopathy, and dementia in a very old Finnish population

Senile systemic amyloidosis (SSA) and cerebral amyloid angiopathy (CAA) are amyloid disorders, which typically manifest with old age. The aim of our study was to examine the possible association of these disorders in very old Finns. We performed a prospective, population-based post mortem study and used histological and immunohistochemical staining methods to verify the presence of these types of amyloid. All 63 subjects (59% of the 107 individuals 95 years of age or more, who died during the 10-year follow-up study), 53 women and 10 men), had been neurologically examined. The prevalence of SSA and its association with CAA, dementia, and neuropathologically verified AD was analyzed. Overall SSA occurred in 23 (37%) and CAA in 28 (44%) of the 63 subjects. At clinical examination 41 individuals (65%) were demented; 24 (38%) had Alzheimer's disease. SSA showed no association with the presence of CAA (P = 0.45), clinical dementia (P = 0.09), or Alzheimer's disease (P = 0.21), or sex (P = 0.53). Our prospective population based study shows that SSA and CAA are frequent in very old Finns, but they do not associate.

Cerebral amyloid angiopathy in a 95+ cohort: complement activation and apolipoprotein E (ApoE) genotype

There is growing evidence that in Alzheimer's disease (AD) amyloid beta-protein (Abeta) triggers a chronic inflammatory reaction in cerebral amyloid plaques, including complement proteins. Abeta also accumulates cerebrovascularly in age- and AD-associated cerebral amyloid angiopathy (CAA). We investigated complement proteins in CAA in a population-based series using histological and immunohistochemical staining methods. The 74 subjects, aged 95 years or more, had undergone clinical neurological examination and apolipoprotein E (ApoE) genotyping. The brains had been studied for AD post-mortem, allowing us to relate the histopathological findings to clinical and genetic conditions. CAA with congophilic amyloid was found in 36/74 individuals (48.6%). The vascular amyloid deposits immunoreacted with antibodies to Abeta and complements 3d (C3d) and 9 (C9). The positivity in complement stains increased with growing severity of CAA (P = 0.001). The presence of CAA associated with ApoE epsilon4 (P = 0.0005) and overrepresentation of epsilon4 among those with moderate or severe vs. mild CAA (P = 0.03) was demonstrated. The presence of CAA associated with dementia (P = 0.01), which was contributed by both epsilon4+ (P = 0.02) and epsilon4- (P = 0.06) subjects. Our study shows that complement proteins are deposited in the affected vessels in Abeta-associated CAA. They may solely represent the cerebral Abeta- burden associated to inflammatory stimuli, or signal a contribution in the clearance of cerebral Abeta, thereby contributing to the events associated with evolution of clinical dementia. Our results demonstrate a strong association between CAA and ApoE epsilon4 as well as dementia and suggest that the contribution of CAA to dementia is largely independent of ApoE epsilon4.

Cutis laxa in hereditary gelsolin amyloidosis

BACKGROUND

Hereditary gelsolin amyloidosis (AGel amyloidosis) is an age-associated systemic disease with global distribution, caused by a G654A or G654T gelsolin gene mutation. Cutis laxa is a principal clinical manifestation of this disease. However, only few data on the dermatological involvement are available, and the pathogenesis of this amyloidosis-associated form of cutis laxa has remained unknown.

OBJECTIVES

To elucidate the pathomechanism of this less well-known genodermatosis.

METHODS

We performed systematic clinical, histological, immunohistochemical and ultrastructural skin biopsy studies in 12 patients with a G654A gelsolin gene mutation. For comparison, skin specimens from 10 control subjects were analysed.

RESULTS

All patients had clinically characteristic cutis laxa, and frequently other signs of symptomatic skin disease such as increased fragility and risk for intracutaneous bleeding. All patients showed cutaneous deposition of gelsolin amyloid (AGel), mainly attached to basement membranes or basal laminae of various cutaneous structures, dermal nerves and blood vessel walls, and elastic fibres, particularly in the lower reticular dermis. AGel often encircled the elastic fibres, and colocalized with amyloid P component (AP), an elastic fibre microfibrillar sheath-associated protein. Fragmentation and loss of elastic fibres, epidermal atrophy, and reduction of dermal appendages were also common. Antibodies to wild-type gelsolin bound to S-100-positive epidermal dendritic cells, a previously unrecognized immunoreaction. Patients had fewer gelsolin-positive dendritic cells than controls.

CONCLUSIONS

Widespread skin involvement with AGel deposition and elastic fibre involvement are essential pathological features in AGel amyloidosis, and contribute to the characteristic cutis laxa, dramatic in old age. Codistribution of AGel and AP, with demonstrated specific binding affinity for amyloid fibrils, suggests that elastic fibre-associated AP acts as a matrix for cutaneous amyloid deposition in AGel amyloidosis.

Neuromuscular pathology in hereditary gelsolin amyloidosis

Hereditary gelsolin amyloidosis (AGel amyloidosis) is a systemic disorder reported worldwide in kindreds with a G654A or G654T gelsolin gene mutation. The clinically characteristic peripheral nerve involvement has been poorly characterized morphologically, and its pathogenesis remains unknown. We studied peripheral nerve and skeletal muscle biopsy or autopsy specimens of 35 patients with a G654A gelsolin gene mutation. Histological, immunohistochemical, and electron microscopic studies showed consistent deposition of gelsolin amyloid (AGel), particularly in the vascular walls and perineurial sheaths. Nerve roots were more severely affected than distal nerves. The amyloid deposits also displayed variable immunoreactivity for apolipoprotein E, amyloid P component, cystatin C, and alpha-smooth muscle actin. Sural nerve morphometry showed preferential age-related large myelinated nerve fiber loss and reduction of myelin sheath cross-sectional area. There was evidence of denervation atrophy and fiber type grouping in skeletal muscle. Our study shows that marked proximal nerve involvement with AGel angiopathy is an essential feature of AGel amyloidosis. The preferential large fiber loss, not generally seen in amyloid neuropathy, may be caused by ischemia due to AGel angiopathy. Deficient actin modulation by variant gelsolin in neurons and Schwann cells, however, may alter axonal transport and myelination and contribute to AGel polyneuropathy.