In vitro modulation of T cells in myasthenia gravis by low-dose IL-2.

Follicular helper (Tfh), peripheral helper (Tph), and regulatory (Treg) T cells are involved in myasthenia gravis (MG) pathogenesis, an autoimmune disorder arising from autoantibodies targeting neuromuscular junction proteins. This study explores the impact of low-dose IL-2 on Tfh, Tph, and Treg cells in vitro in MG. Acetylcholine-receptor antibody-positive MG (AChR-MG), muscle-specific kinase antibody-positive MG (MuSK-MG) patients, and healthy controls (HC) were studied. Blood cells were cultured with/without IL-2 and compared by the ratios of IL-2 stimulated/unstimulated cultures. In both AChR-MG and MuSK-MG patients, CD25+FoxP3+Tregs were lower, while CXCR5+PD-1+ or ICOS+Tfh and CXCR5-PD-1+ or ICOS+Tph cells were higher compared with HC. Among the MG group, the FoxP3+ Treg cells in AChR-MG patients were even lower compared with MuSK-MG patients. In vitro IL-2 stimulation increased Tregs in all groups while decreasing PD-1+/ICOS+Tfh and PD-1+/ICOS+Tph populations. The fold-increase ratio of Tregs and the fold-decrease ratio of PD-1+ or ICOS+Tfh and ICOS+Tph cells in AChR-MG and MuSK-MG patients were greater than in HCs. Low-dose IL-2 treatment may balance Tfh, Tph, and Treg cells in MG patients, offering a potential opportunity for disease modulation.

RTN2 deficiency results in an autosomal recessive distal motor neuropathy with lower limb spasticity.

Heterozygous RTN2 variants have been previously identified in a limited cohort of families affected by autosomal dominant spastic paraplegia (SPG12-OMIM:604805) with a variable age of onset. Nevertheless, the definitive validity of SPG12 remains to be confidently confirmed due to the scarcity of supporting evidence. In this study, we identified and validated seven novel or ultra-rare homozygous loss-of-function RTN2 variants in 14 individuals from seven consanguineous families with distal hereditary motor neuropathy (dHMN) using exome, genome and Sanger sequencing coupled with deep-phenotyping. All affected individuals (seven males and seven females, aged 9-50 years) exhibited weakness in the distal upper and lower limbs, lower limb spasticity and hyperreflexia, with onset in the first decade of life. Nerve conduction studies revealed axonal motor neuropathy with neurogenic changes in the electromyography. Despite a slowly progressive disease course, all patients remained ambulatory over a mean disease duration of 19.71 ± 13.70 years. Characterization of Caenorhabditis elegans RTN2 homologous loss-of-function variants demonstrated morphological and behavioural differences compared with the parental strain. Treatment of the mutant with an endoplasmic/sarcoplasmic reticulum Ca2+ reuptake inhibitor (2,5-di-tert-butylhydroquinone) rescued key phenotypic differences, suggesting a potential therapeutic benefit for RTN2-disorder. Despite RTN2 being an endoplasmic reticulum (ER)-resident membrane shaping protein, our analysis of patient fibroblast cells did not find significant alterations in ER structure or the response to ER stress. Our findings delineate a distinct form of autosomal recessive dHMN with pyramidal features associated with RTN2 deficiency. This phenotype shares similarities with SIGMAR1-related dHMN and Silver-like syndromes, providing valuable insights into the clinical spectrum and potential therapeutic strategies for RTN2-related dHMN.

Thymic gene expression analysis reveals a potential link between HIF-1A and Th17/Treg imbalance in thymoma associated myasthenia gravis.

Myasthenia gravis (MG) is an immune-mediated disease frequently associated with thymic changes. Increased T helper 17 (Th17) cell activity and dysfunctional regulatory T (Treg) cells have been demonstrated in subgroups of MG. On the other hand, hypoxia-inducible factor 1 (HIF-1) has been shown to regulate the Th17/Treg balance by inducing Th17 differentiation while attenuating Treg development. To identify the underlying mechanisms of different thymic pathologies in MG development, we evaluated thymic samples from thymoma-associated myasthenia gravis (TAMG), MG with hyperplasia (TFH-MG) and thymoma without MG (TOMA) patients. Differential gene expression analysis revealed that TAMG and TFH-MG cells are associated with different functional pathways. A higher RORC/FOXP3 ratio provided evidence for Th17/Treg imbalance in TAMG potentially related to increased HIF1A. The hypoxic microenvironment in thymoma may be a driver of TAMG by increasing HIF1A. These findings may lead to new therapeutic approaches targeting HIF1A in the development of TAMG.

Disease activity in chronic inflammatory demyelinating polyneuropathy: association between circulating B-cell subsets, cytokine levels, and clinical outcomes.

Chronic inflammatory demyelinating polyneuropathy (CIDP), a common and treatable autoimmune neuropathy, is frequently misdiagnosed. The aim of this study is to evaluate the relationship between immunological markers and clinical outcome measures in a mixed cohort of patients with typical CIDP and CIDP variants at different disease stages. Twenty-three typical, 16 multifocal and five distal CIDP patients were included. Twenty-five sex and age-matched healthy controls and 12 patients with Charcot-Marie-Tooth type 1A (CMT1A) disease served as controls. Peripheral B-cell populations were analyzed by flow cytometry. IL6, IL10, TNFA mRNA and mir-21, mir-146a, and mir-155-5p expression levels were evaluated by real-time polymerase chain reaction in peripheral blood mononuclear cells (PBMC) and/or skin biopsy specimens. Results were then assessed for a possible association with clinical disability scores and intraepidermal nerve fiber densities (IENFD) in the distal leg. We detected a significant reduction in naive B cells (P ≤ 0.001), plasma cells (P ≤ 0.001) and regulatory B cells (P < 0.05), and an elevation in switched memory B cells (P ≤ 0.001) in CIDP compared to healthy controls. CMT1A and CIDP patients had comparable B-cell subset distribution. CIDP cases had significantly higher TNFA and IL10 gene expression levels in PBMC compared to healthy controls (P < 0.05 and P ≤ 0.01, respectively). IENFDs in the distal leg showed a moderate negative correlation with switched memory B-cell ratios (r = -0.51, P < 0.05) and a moderate positive correlation with plasma cell ratios (r = 0.46, P < 0.05). INCAT sum scores showed a moderate positive correlation with IL6 gene expression levels in PBMC (r = 0.54, P < 0.05). Altered B-cell homeostasis and IL10 and TNFA gene expression levels imply chronic antigen exposure and overactivity in the humoral immune system, and seem to be a common pathological pathway in both typical CIDP and CIDP variants.

Electrodiagnostic methods to verify Guillain-Barré syndrome subtypes in Istanbul: A prospective multicenter study.

BACKGROUND AND AIMS: This study aimed to identify the clinical characteristics and electrodiagnostic subtypes of Guillain-Barré syndrome (GBS) in Istanbul. METHODS: Patients with GBS were prospectively recruited between April 2019 and March 2022 and two electrodiagnostic examinations were performed on each patient. The criteria of Ho et al., Hadden et al., Rajabally et al., and Uncini et al. were compared for the differentiation of demyelinating and axonal subtypes, and their relations with anti-ganglioside antibodies were analyzed. RESULTS: One hundred seventy-seven patients were included, 69 before the coronavirus disease 2019 pandemic (April 2019-February 2020) and 108 during the pandemic (March 2020-March 2022), without substantial changes in monthly frequencies. As compared with the criteria of Uncini et al., demyelinating GBS subtype diagnosis was more frequent according to the Ho et al. and Hadden et al. criteria (95/162, 58.6% vs. 110/174, 63.2% and 121/174, 69.5%, respectively), and less frequent according to Rajabally et al.'s criteria (76/174, 43.7%). Fourteen patients' diagnoses made using Rajabally et al.'s criteria were shifted to the other subtype with the second electrodiagnostic examination. Of the 106 analyzed patients, 22 had immunoglobulin G anti-ganglioside antibodies (14 with the axonal subtype). They had less frequent sensory symptoms (54.5% vs. 83.1%, p = 0.009), a more frequent history of previous gastroenteritis (54.5% vs. 22.9%, p = 0.007), and a more severe disease as compared with those without antibodies. INTERPRETATION: Serial electrodiagnostic examinations are more helpful for accurate subtype diagnosis of GBS because of the dynamic pathophysiology of the disease. We observed no significant increase in GBS frequency during the pandemic in this metropolis.

Phenotypic features of RETREG1-related hereditary sensory autonomic neuropathy.

BACKGROUND AND AIMS: Homozygous loss-of-function mutations in the RETREG1 gene result in Hereditary Sensory Autonomic Neuropathy Type 2B. Clinical features include pain loss, autonomic disturbances, and upper motor neuron features. METHODS: We evaluated the clinical and genetic features of seven patients from four families with RETREG1 variants. RESULTS: Five patients were male. The median age of disease onset was 7.00 ± 2.81 (between 2 and 10 years). A combination of painless wounds, trophic changes, and foot ulcerations was the presenting symptom in five patients and walking difficulties in two. Motor symptoms were present in five patients. In a median disease duration of 30.00 ± 12.88 years, five patients had osteomyelitis, and three had toe amputations. A history of renal disease was present in one family. In another family, three affected siblings had short stature and a history of delayed puberty. Although sensory signs predominated the clinical findings, various degrees of motor signs such as muscle weakness, spasticity, and brisk tendon reflexes were noted in all patients. Nerve conduction studies showed axonal sensory-motor neuropathy in five patients and sensory neuropathy in two. Three pathogenic variants were identified in the RETREG1 gene. Two unrelated patients had a homozygous c.433C > T/p.(Gln145*), one a homozygous c.826delA/p.(Ser276Valfs*8), and the last had a novel homozygous c.102delC/p.(Ala35Glnfs*349) variants. INTERPRETATION: In our study, all patients showed signs and symptoms consistent with pain insensitivity. Although shadowed by sensory symptoms, motor signs were noted in our patients. Further studies are necessary to clarify the causal relationship between extra-neurological features and RETREG1 mutations.

Disease activity in chronic inflammatory demyelinating polyneuropathy: A comparative study of clinical and skin biopsy markers.

INTRODUCTION/AIMS: Epidermal nerve fiber involvement in chronic inflammatory demyelinating neuropathy (CIDP) has been reported in a limited number of patients. We quantified small-fiber involvement in a mixed cohort of patients with typical CIDP and CIDP variants to evaluate relationships with clinical outcome measures at different disease stages. METHODS: Intraepidermal nerve fiber densities (IENFDs) were evaluated by skin punch biopsies of 23 patients with CIDP and 13 healthy controls at the forearm, thigh, and distal leg. Skin sections were optimally interpreted in all three regions in 16 CIDP patients and 10 age- and sex-matched healthy controls. Statistical analysis was performed in these subjects. RESULTS: The IENFDs in forearm, thigh, and distal leg were similar among seven typical CIDP and nine CIDP variants. IENFDs in those regions were significantly reduced in CIDP compared with healthy controls, with a moderate negative correlation with scores on the International Neuropathy Cause and Treatment (INCAT) Upper Limb Functional Disability Scale. The reduction in IENFD compared with controls was more remarkable in the distal leg. In clinically unstable CIDP patients, the IENFDs of distal leg and forearm were significantly reduced compared with stable CIDP patients and controls. Stable CIDP patients had significantly reduced IENFDs in distal leg and forearm compared with controls. DISCUSSION: In this exploratory study, we confirm that small fibers are also affected in CIDP. Larger studies are needed to explore longitudinal changes of IENFD in CIDP and its relation to disease stage.

Phenotypical spectrum of SACS variants: Neuromuscular perspective of a complex neurodegenerative disorder.

OBJECTIVES: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is caused by the SACS gene variants. Main clinical features include early-onset and progressive cerebellar ataxia, spasticity, sensorimotor polyneuropathy. However, the phenotypic spectrum expanded with the increased availability of next-generation sequencing methods. MATERIALS AND METHODS: Herein, we describe the clinical features of nine patients from seven unrelated families with SACS variants from the cohort of the Neuromuscular Disorders Unit of the Neurology Department of the Istanbul University, Istanbul Faculty of Medicine. RESULTS: Seven patients were male. Seven patients in our cohort had disease onset in the first decade of life. Eight patients were born to consanguineous marriages. Distal weakness in the lower limbs was a prominent feature in all of our patients. Seven patients had ataxia, and six patients had spasticity. Interestingly, one patient showed an isolated Charcot-Marie-Tooth-like phenotype. Five patients showed sensorimotor demyelinating polyneuropathy in the nerve conduction studies. Linear pontine hypointensity was the most frequent cranial magnetic resonance imaging (MRI) abnormality. Two patients with a later disease onset had a homozygous c.11542_11544delATT (p.Ile3848del) variant. The rest of the identified variants were scattered throughout the SACS gene. CONCLUSIONS: Atypical clinical features in our patients highlight that the phenotypic spectrum of ARSACS can be observed in a wide range.

The Complex Genetic Landscape of Hereditary Ataxias in Turkey and Implications in Clinical Practice.

BACKGROUND: The genetic and epidemiological features of hereditary ataxias have been reported in several populations; however, Turkey is still unexplored. Due to high consanguinity, recessive ataxias are more common in Turkey than in Western European populations. OBJECTIVE: To identify the prevalence and genetic structure of hereditary ataxias in the Turkish population. METHODS: Our cohort consisted of 1296 index cases and 324 affected family members. Polymerase chain reaction followed by Sanger sequencing or fragment analysis were performed to screen for the trinucleotide repeat expansions in families with a dominant inheritance pattern, as well as in sporadic cases. The expansion in the frataxin (FXN) gene was tested in all autosomal recessive cases and in sporadic cases with a compatible phenotype. Whole-exome sequencing was applied to 251 probands, selected based on the family history, age of onset, and phenotype. RESULTS: Mutations in known ataxia genes were identified in 30% of 1296 probands. Friedreich's ataxia was found to be the most common recessive ataxia in Turkey, followed by autosomal recessive spastic ataxia of Charlevoix-Saguenay. Spinocerebellar ataxia types 2 and 1 were the most common dominant ataxias. Whole-exome sequencing was performed in 251 probands with an approximate diagnostic yield of 50%. Forty-eight novel variants were found in a plethora of genes, suggesting a high heterogeneity. Variants of unknown significance were discussed in light of clinical data. CONCLUSION: With the large sample size recruited across the country, we consider that our results provide an accurate picture of the frequency of hereditary ataxias in Turkey. © 2021 International Parkinson and Movement Disorder Society.

An Exploratory Study of Cognitive Involvement in Hereditary Transthyretin Amyloidosis.

OBJECTIVES: Hereditary amyloidogenic transthyretin (ATTRv) amyloidosis is an autosomal dominant disorder caused by mutations of the transthyretin (TTR) gene. The mutant ATTRv protein causes a systemic accumulation of amyloid fibrils in various organs. TTR is an important protein in the central nervous system physiology for the maintenance of normal cognitive process during aging, amidated neuropeptide processing, and nerve regeneration. The neuroprotective effect of transthyretin has been widely documented in animal models. Cognitive consequences of the mutant TTR in hereditary ATTRv amyloidosis patients remain still to be elucidated. We designed this study to investigate the cognitive involvement in ATTRv amyloidosis. METHODS: Detailed neuropsychological tests and cranial MRIs were performed. Biomarkers including amyloid beta 1-42, total tau, and phosphorylated tau were investigated in the cerebrospinal fluid samples. RESULTS: Median age of the cohort was 52 years (ranges 34-72). Neuropsychological assessment results were compatible with impaired executive functions (in all patients except one with only bilateral carpal tunnel syndrome, long-term visual and long-term verbal memory (severe in four patients and moderate in one). Visuospatial judgment and perception were impaired in six. Mean cerebrospinal fluid Aß1-42 (pg/ml) was 878.0 ± 249.5 in patients with cortical atrophyin MRI whereas 1210.0 ± 45.9 in patients without any cortical atrophy. Cranial MRI showed cortical atrophy in six patients (6/10). CONCLUSION: Our data showed the significance of the TTR protein in cognitive functions and highlighted the importance of the close follow-up of cognitive functions in ATTRv amyloidosis patients.

Revisiting the complex architecture of ALS in Turkey: Expanding genotypes, shared phenotypes, molecular networks, and a public variant database.

The last decade has proven that amyotrophic lateral sclerosis (ALS) is clinically and genetically heterogeneous, and that the genetic component in sporadic cases might be stronger than expected. This study investigates 1,200 patients to revisit ALS in the ethnically heterogeneous yet inbred Turkish population. Familial ALS (fALS) accounts for 20% of our cases. The rates of consanguinity are 30% in fALS and 23% in sporadic ALS (sALS). Major ALS genes explained the disease cause in only 35% of fALS, as compared with ~70% in Europe and North America. Whole exome sequencing resulted in a discovery rate of 42% (53/127). Whole genome analyses in 623 sALS cases and 142 population controls, sequenced within Project MinE, revealed well-established fALS gene variants, solidifying the concept of incomplete penetrance in ALS. Genome-wide association studies (GWAS) with whole genome sequencing data did not indicate a new risk locus. Coupling GWAS with a coexpression network of disease-associated candidates, points to a significant enrichment for cell cycle- and division-related genes. Within this network, literature text-mining highlights DECR1, ATL1, HDAC2, GEMIN4, and HNRNPA3 as important genes. Finally, information on ALS-related gene variants in the Turkish cohort sequenced within Project MinE was compiled in the GeNDAL variant browser (www.gendal.org).

The first biallelic missense mutation in the FXN gene in a consanguineous Turkish family with Charcot-Marie-Tooth-like phenotype.

Charcot-Marie-Tooth (CMT) disease is the most common inherited neuropathy with a prevalence of 1 in 2500 individuals worldwide. Here, we report three Turkish siblings from consanguineous parents presenting with a CMT-like phenotype who carry a homozygous c.493C>T, p.Arg165Cys mutation in the FXN gene that is the only known causative gene for Friedreich's ataxia (FRDA). The identified missense mutation has been reported previously in two FRDA cases in compound heterozygosity with the common GAA repeat expansion in the first intron of the FXN gene. Analysis of skin biopsy samples from our family indicated that the mutation does not affect the expression levels of the frataxin, pointing to functional impairment of the corresponding protein. The CMT phenotype in the siblings was associated with visual impairment, optic nerve atrophy, and dysarthria. To the best of our knowledge, this family represents the first FXN missense mutation in homozygosity and challenges the notion that missense mutations have not been reported yet due to their embryonic lethality. Furthermore, this finding poses an interesting genetic overlap between autosomal recessive CMT and FRDA that we believe may have important implications on understanding the pathogenesis of these neurological disorders.

A novel homozygous FBXO38 variant causes an early-onset distal hereditary motor neuronopathy type IID.

Distal hereditary motor neuronopathies (dHMN) are a genetically heterogeneous group of neuromuscular disorders caused by anterior horn cell degeneration and progressive distal muscle weakness. A heterozygous missense variant in FBXO38 has been previously described in two families affected by autosomal-dominant dHMN. In this paper, we describe a homozygous missense variant in FBXO38 (c.1577G>A; p.(Arg526Gln)) in a young Turkish female, offspring of consanguineous parents, with a congenital mild neuronopathy with idiopathic toe walking, normal sensory examination, and hearing loss. This work is the first to describe a novel homozygous variant and a suggested loss of function mechanism in FBXO38, expanding the dHMN type IID phenotype.

Adult-onset phenylketonuria with rapidly progressive dementia and parkinsonism.

Phenylketonuria (PKU) is an autosomal recessive metabolic disorder due to mutations in the phenylalanine hydroxylase (PAH) gene, which converts phenylalanine (PHE) to tyrosine. Although it is principally a childhood disorder, in rare cases, the first signs of PKU may develop in late adulthood resembling common neurological diseases. Here we report a 59-year-old, previously normal functioning man who was admitted with blurred vision, cognitive problems, and gait difficulty that began 8 months before. He had brisk reflexes and left side dominant parkinsonism. His Mini-Mental State Examination (MMSE) score was 25/30, and neuropsychological evaluation revealed a dysexecutive syndrome with simultanagnosia and constructional apraxia. His Clinical Dementia Rating score (CDR) was 1. Cranial MRI revealed bilateral diffuse hyperintense lesions in parietal and occipital white matter in T2, fluid-attenuated inversion recovery, and diffusion weighted images. Diagnostic workup for rapidly progressive dementias was all normal except PHE level which was found to be highly elevated (1075 µmol/L, normal 39-240 µmol/L) with normal tyrosine level (61.20 µmol/L, normal 35-100 µmol/L). Three months after PHE-restricted diet, his cognitive impairment and signs of parkinsonism significantly improved, with MRI scan unchanged. This case demonstrates that late-onset PKU is a rare, treatable cause of rapidly progressive dementia and parkinsonism with certain constellations such as consanguinity and white matter abnormalities (WMAs) in imaging.

Clinical and neuroradiological spectrum of biallelic variants in NOTCH3.

BACKGROUND: NOTCH3 encodes a transmembrane receptor critical for vascular smooth muscle cell function. NOTCH3 variants are the leading cause of hereditary cerebral small vessel disease (SVD). While monoallelic cysteine-involving missense variants in NOTCH3 are well-studied in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), patients with biallelic variants in NOTCH3 are extremely rare and not well characterised. METHODS: In this study, we present clinical and genetic data from 25 patients with biallelic NOTCH3 variants and conduct a literature review of another 25 cases (50 patients in total). Brain magnetic resonance imaging (MRI) were analysed by expert neuroradiologists to better understand the phenotype associated with biallelic NOTCH3 variants. FINDINGS: Our systematic analyses verified distinct genotype-phenotype correlations for the two types of biallelic variants in NOTCH3. Biallelic loss-of-function variants (26 patients) lead to a neurodevelopmental disorder characterised by spasticity, childhood-onset stroke, and periatrial white matter volume loss resembling periventricular leukomalacia. Conversely, patients with biallelic cysteine-involving missense variants (24 patients) fall within CADASIL spectrum phenotype with early adulthood onset stroke, dementia, and deep white matter lesions without significant volume loss. White matter lesion volume is comparable between patients with biallelic cysteine-involving missense variants and individuals with CADASIL. Notably, monoallelic carriers of loss-of-function variants are predominantly asymptomatic, with only a few cases reporting nonspecific headaches. INTERPRETATION: We propose a NOTCH3-SVD classification depending on dosage and variant type. This study not only expands our knowledge of biallelic NOTCH3 variants but also provides valuable insight into the underlying mechanisms of the disease, contributing to a more comprehensive understanding of NOTCH3-related SVD. FUNDING: The Wellcome Trust, the MRC.

A novel homozygous loss-of-function variant in SOD1 causing progressive spastic tetraplegia and axial hypotonia.

SOD1 is the first identified causative gene for amyotrophic lateral sclerosis. Recently, a novel syndrome, presenting with severe childhood-onset spastic tetraplegia and axial hypotonia caused by the homozygous truncating variants in the SOD1 gene, is described. A 22-month-old boy was admitted with a loss of motor functions that began at the age of 9 months. Neurological was significant for axial hypotonia with spastic tetraplegia and hyperekplexia-like jerky movements. In WES, we found a novel homozygous variant (c.52_56del5ins154) in the SOD1 gene, resulting in a total loss of SOD1 mRNA expression in the real-time PCR analysis. Western blot analyses confirmed the lack of protein production. Erythrocyte superoxide dismutase enzymatic activity was nearly abolished. The heterozygous family members displayed reduced superoxide dismutase 1 protein expression and enzymatic activity (by about 40%), compared with the healthy control. Our study expanded the mutation spectrum of SOD1.

Thymoma patients with or without myasthenia gravis have increased Th17 cells, IL-17 production and ICOS expression.

Thymoma associated myasthenia gravis (TAMG) is a small disease subgroup with autoantibodies against the acetylcholine receptor. The aim of this study was to assess the role of T helper (Th) cells in TAMG compared to thymoma patients without MG (TOMA) and healthy controls (HC). Peripheral blood cells were used for intracellular cytokine measurements and phenotyping of CD4+ Th cells. IL-21 and IL-4 productions and peripheral Th cells were higher in TAMG compared to TOMA patients and HC. Increases of ICOS and Th17 population were detected both in TAMG and TOMA groups. Higher IL-10 and Th1 population have been observed related to thymectomy. ICOS expression and Th17 induced by thymoma may contribute to the development of TAMG.

Lumbar Spinal Stenosis: A Rare Presentation of Hereditary Transthyretin Amyloidosis.

Hereditary transthyretin amyloidosis (hATTR) is caused by the mutations of the transthyretin (TTR) gene. Length dependent sensory-motor neuropathy with autonomic involvement is the hallmark of the disease. However, it can manifest with unusual phenotypes. A 53-year-old man presented with progressive weakness in lower limbs and operated for lumbar spinal stenosis. The progression of weakness restarted after two years with the addition of symptoms related to polyneuropathy. Electrodiagnostic studies revealed sensorimotor polyneuropathy with autonomic involvement. Sural nerve biopsy disclosed amyloid deposits. Genetic testing of TTR gene identified Glu89Gln mutation. Two years after the diagnosis, he had another decompressive surgery for lumbar spinal stenosis. Histopathological examination of ligamentum flavum specimens revealed amyloid deposits. During the follow up, he was diagnosed with laryngeal amyloidosis, which is an unusual manifestation. Seven years after the diagnosis, he died due to cardiac complications. Our patient suggested that hATTR with Glu89Gln may present with atypical symptoms. Clinicians should carefully look for hATTR in recurrent lumbar stenosis.

Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (canvas): an important cause of late-onset ataxia with unique clinical features.

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) is a late-onset, slowly progressive disorder characterized by cerebellar ataxia, sensory neuropathy and bilateral vestibulopathy. Recently, a biallelic intronic AAGGG repeat expansion, (AAGGG)exp, in the Replication Factor C1 (RFC1) gene was identified as the cause of this disorder. In this study, we describe the phenotypic features of five patients from five different families diagnosed as CANVAS. The mean age at onset was 49.00 ± 9.05 years (between 34 and 56 years) and the most frequent presenting symptom in CANVAS was gait ataxia, followed by sensory disturbances. Persistent coughing was prominent in three patients, and it preceded the onset of ataxia and sensory symptoms in two patients. Parental consanguinity was present in three patients. Two patients showed symptoms or signs suggesting autonomic involvement. Sural nerve biopsy revealed axonal neuropathy in two patients. The mean age at onset was 49.00 ± 9.05 years (between 34 and 56 years) and the most frequent presenting symptom in CANVAS was gait ataxia, followed by sensory disturbances. Persistent coughing was prominent in three patients, and it preceded the onset of ataxia and sensory symptoms in two patients. Parental consanguinity was present in three patients. Two patients showed symptoms or signs suggesting autonomic involvement. Sural nerve biopsy revealed axonal neuropathy in two patients. Our study describes clinical findings, histopathological features and diagnostic clues of CANVAS from Turkey, a country with a high consanguineous marriage rate. Repeat expansion in the RFC1 gene should be considered in all cases with late-onset ataxia, especially when sensory disturbances, vestibular involvement and persistent coughing coexist.