Alternative splicing expands the clinical spectrum of NDUFS6-related mitochondrial disorders.

PURPOSE: We describe 3 families with Charcot-Marie-Tooth neuropathy (CMT), harboring a homozygous NDUFS6 NM_004553.6:c.309+5G>A variant previously linked to fatal Leigh syndrome. We aimed to characterize clinically and molecularly the newly identified patients and understand the mechanism underlying their milder phenotype. METHODS: The patients underwent extensive clinical examinations. Exome sequencing was done in 4 affected individuals. The functional effect of the c.309+5G>A variant was investigated in patient-derived EBV-transformed lymphoblasts at the complementary DNA, protein, and mitochondrial level. Alternative splicing was evaluated using complementary DNA long-read sequencing. RESULTS: All patients presented with early-onset, slowly progressive axonal CMT, and nystagmus; some exhibited additional central nervous system symptoms. The c.309+5G>A substitution caused the expression of aberrantly spliced transcripts and negligible levels of the canonical transcript. Immunoblotting showed reduced levels of mutant isoforms. No detectable defects in mitochondrial complex stability or bioenergetics were found. CONCLUSION: We expand the clinical spectrum of NDUFS6-related mitochondrial disorders to include axonal CMT, emphasizing the clinical and pathophysiologic overlap between these 2 clinical entities. This work demonstrates the critical role that alternative splicing may play in modulating the severity of a genetic disorder, emphasizing the need for careful consideration when interpreting splice variants and their implications on disease prognosis.

The FGF14 GAA repeat expansion in Greek patients with late-onset cerebellar ataxia and an overview of the SCA27B phenotype across populations.

A pathogenic GAA repeat expansion in the first intron of the fibroblast growth factor 14 gene (FGF14) has been recently identified as the cause of spinocerebellar ataxia 27B (SCA27B). We herein screened 160 Greek index cases with late-onset cerebellar ataxia (LOCA) for FGF14 repeat expansions using a combination of long-range PCR and bidirectional repeat-primed PCRs. We identified 19 index cases (12%) carrying a pathogenic FGF14 GAA expansion, a diagnostic yield higher than that of previously screened repeat-expansion ataxias in Greek LOCA patients. The age at onset of SCA27B patients was 60.5 ± 12.3 years (range, 34-80). Episodic onset (37%), downbeat nystagmus (32%) and vertigo (26%) were significantly more frequent in FGF14 expansion-positive cases compared to expansion-negative cases. Beyond typical cerebellar signs, SCA27B patients often displayed hyperreflexia (47%) and reduced vibration sense in the lower extremities (42%). The frequency and phenotypic profile of SCA27B in Greek patients was similar to most other previously studied populations. We conclude that FGF14 GAA repeat expansions are the commonest known genetic cause of LOCA in the Greek population and recommend prioritizing testing for FGF14 expansions in the diagnostic algorithm of patients with LOCA.

Transthyretin Amyloidosis Cardiomyopathy in Greece: Clinical Insights from the National Referral Center.

BACKGROUND: Clinical characteristics and outcomes of patients with transthyretin amyloidosis cardiomyopathy (ATTR-CM) vary by region, necessitating the acquisition of country-specific evidence for proper management. METHODS: This is an observational study including sequential patients presenting in the Amyloidosis Reference Center of Greece, from 01/2014 to 12/2022. ATTR-CM was diagnosed by positive scintigraphy and exclusion of light-chain amyloidosis or positive biopsy typing. Genetic testing was performed in all cases. RESULTS: One-hundred and nine ATTR-CM patients were included (median age, 81 years) of which 15 carried TTR mutations (27% Val30Met). Most patients (82%) presented with heart failure and 59% with atrial fibrillation, while 10% had aortic stenosis. Importantly, 78 (71.6%) had clinically significant extracardiac manifestations (45% musculoskeletal disorder, 40% peripheral neuropathy and 33% gastrointestinal symptoms). Sixty-five (60%) received disease-specific treatment with tafamidis. Estimated median survival was 48 months; advanced NYHA class, National Amyloidosis Center stage, eGFR<45 ml/kg/1.73m2, NT-pro-BNP>5000 pg/mL were associated with worse survival, while tafamidis treatment was associated with improved survival in patients with IVS≥ 12 mm. DISCUSSION: These are the first data describing the characteristics, management, and outcomes of patients with ATTR-CM in Greece, which could influence local guidelines. SHORT TITLE: Transthyretin cardiomyopathy in Greece.

Mutational screening of Greek patients with axonal Charcot-Marie-Tooth disease using targeted next-generation sequencing: Clinical and molecular spectrum delineation.

BACKGROUND AND AIMS: Axonal forms of Charcot-Marie-Tooth disease (CMT) are classified as CMT2, distal hereditary motor neuropathy (dHMN) or hereditary sensory neuropathy (HSN) and can be caused by mutations in over 100 genes. We presently aimed to investigate for the first time the genetic landscape of axonal CMT in the Greek population. METHODS: Sixty index patients with CMT2, dHMN or HSN were screened by a combination of Sanger sequencing (GJB1) and next-generation sequencing custom-made gene panel covering 24 commonly mutated genes in axonal CMT. RESULTS: Overall, 20 variants classified as pathogenic or likely pathogenic were identified in heterozygous state in 20 index cases, representing 33.3% of the cohort. Of these, 14 were known pathogenic/likely pathogenic and six were designated as such according to ACMG classification, after in silico evaluation, testing for familial segregation and further literature review. The most frequently involved genes were GJB1 (11.7%), MPZ (5%) and MFN2 (5%), followed by DNM2 (3.3%) and LRSAM1 (3.3%). Single cases were identified with mutations in BSCL2, HSPB1 and GDAP1. INTERPRETATION: A wide phenotypic variability in terms of severity and age of onset was noted. Given the limited number of genes tested, the diagnostic yield of the present panel compares favourably with studies in other European populations. Our study delineates the genetic and phenotypic variability of inherited axonal neuropathies in the Greek population and contributes to the pathogenicity characterization of further variants linked to axonal neuropathies.

Transthyretin (Pro24Ser) variant amyloidosis: A case report of the first patient in Greece.

OBJECTIVE: Transthyretin cardiac amyloidosis (ATTR-CA) is a rare and potentially fatal disease caused by the accumulation of insoluble transthyretin (TTR) amyloid fibrils in the heart. The symptoms of ATTR-CA are often non-specific, often leading to underdiagnosis. Early diagnosis and treatment have a significant impact on disease progression and mortality. CASE PRESENTATION: In this case we report a 73-year-old male presented with dyspnea on exertion. The patient had a medical history of peripheral neuropathy, bilateral carpal tunnel syndrome, spinal fusion, and a family history of coronary artery disease. Upon his presentation at the Cardiology department, cardiac echo study revealed left and right ventricular hypertrophy with pulmonary hypertension, diastolic dysfunction and a restrictive pattern. Because of the high probability of amyloidosis, the patient underwent a technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) bone scintigraphic study, which confirmed the diagnosis of ATTR-CA. Transthyretin gene sequencing analysis revealed the rare p. Pro24Ser pathogenic variant. Final diagnosis was ATTR-CA associated with the proline replaced by serine at position 24 (Pro24Ser) TTR variant, which is rare and only a few cases have been reported worldwide. The patient was treated with tafamidis and inotersen and followed up. CONCLUSION: This case highlights the importance of considering amyloidosis as a differential diagnosis for non-specific symptoms and the need for early diagnosis and management of ATTR-CA.

Pure cerebellar ataxia due to bi-allelic PRDX3 variants including recurring p.Asp202Asn.

Bi-allelic variants in peroxiredoxin 3 (PRDX3) have only recently been associated with autosomal recessive spinocerebellar ataxia characterized by early onset slowly progressive cerebellar ataxia, variably associated with hyperkinetic and hypokinetic features, accompanied by cerebellar atrophy and occasional olivary and brainstem involvement. Herein, we describe a further simplex case carrying a reported PRDX3 variant as well as two additional cases with novel variants. We report the first Brazilian patient with SCAR32, replicating the pathogenic status of a known variant. All presented cases from the Brazilian and Indian populations expand the phenotypic spectrum of the disease by displaying prominent neuroradiological findings. SCAR32, although rare, should be included in the differential diagnosis of sporadic or recessive childhood and adolescent-onset pure and complex cerebellar ataxia.

Screening for the FMR1 premutation in Greek patients with late-onset movement disorders.

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset, X-linked, neurodegenerative disorder that affects premutation carriers of the FMR1 gene. FXTAS is often misdiagnosed as spinocerebellar ataxia (SCA) or Parkinson's disease (PD). Herein, we sought to investigate the frequency, genotypic and phenotypic profile of FXTAS in two cohorts of Greek patients with late-onset movement disorders, one with cerebellar ataxia and the other with PD. In total, 90 index patients with late-onset cerebellar ataxia and 171 with PD were selected. None of the cases had male-to-male transmission. Genetic screening for the FMR1 premutation was performed using standard methodology. The FMR1 premutation was detected in two ataxia patients (2.2%) and two PD patients (1.2%). Additional clinical features in FXTAS patients from the ataxia cohort included neuropathy, mild parkinsonism, cognitive impairment and pyramidal signs. The FXTAS patients from the PD cohort had typical PD. We conclude that, in the Greek population, the FMR1 premutation is an important, albeit rare, cause of late-onset movement disorders. Routine premutation screening should be considered in SCA panel-negative late-onset ataxia cases. Directed premutation screening should be considered in all ataxia and PD cases with additional features suggestive of FXTAS. Our study highlights the importance of FMR1 genetic testing in the diagnosis of late-onset movement disorders.

A Greek National Cross-Sectional Study on Myotonic Dystrophies.

Myotonic Dystrophies (DM, Dystrophia Myotonia) are autosomal dominant inherited myopathies with a high prevalence across different ethnic regions. Despite some differences, mainly due to the pattern of muscle involvement and the age of onset, both forms, DM1 and DM2, share many clinical and genetic similarities. In this study, we retrospectively analyzed the medical record files of 561 Greek patients, 434 with DM1 and 127 with DM2 diagnosed in two large academic centers between 1994-2020. The mean age at onset of symptoms was 26.2 ± 15.3 years in DM1 versus 44.4 ± 17.0 years in DM2 patients, while the delay of diagnosis was 10 and 7 years for DM1 and DM2 patients, respectively. Muscle weakness was the first symptom in both types, while myotonia was more frequent in DM1 patients. Multisystemic involvement was detected in the great majority of patients, with cataracts being one of the most common extramuscular manifestations, even in the early stages of disease expression. In conclusion, the present work, despite some limitations arising from the retrospective collection of data, is the first record of a large number of Greek patients with myotonic dystrophy and emphasizes the need for specialized neuromuscular centers that can provide genetic counseling and a multidisciplinary approach.

Cholesterol levels in plasma and cerebrospinal fluid in patients with clinically isolated syndrome and relapsing-remitting multiple sclerosis.

Cholesterol is essential for myelin formation, but may also modulate mechanisms involved in adaptive immune responses. It is unclear whether lack of remyelination in multiple sclerosis (MS) results from an insufficient capacity of oligodendrocyte precursor cells to differentiate or from cholesterol insufficiency. Several studies have assessed the potential association of lipid profile and its metabolism with demyelination, disability, and disease progression. The aim of the present study was to measure cholesterol levels in plasma and cerebrospinal fluid (CSF) of patients with relapsing remitting MS (RRMS) or with clinically isolated syndrome (CIS), and to investigate whether there is an association between cholesterol levels and disease characteristics. Sixty-two patients with CIS and 46 patients with RRMS were included in the study. All patients had low EDSS and were medication-free at assessment. Forty-eight subjects within the same age range served as controls. Cholesterol concentrations were measured in plasma and in CSF by the same enzymatic - colorimetric method, and were related to clinical status, disease activity in magnetic resonance imaging (MRI) and presence of oligoclonal bands in CSF (OBs). Significantly lower levels of plasma and CSF cholesterol were found in patients compared to controls. Patients with OBs showed significantly lower levels of CSF cholesterol but not plasma cholesterol compared to OBs-negative patients. A positive correlation of plasma cholesterol with age and of CSF cholesterol with EDSS was found. Our results suggest that low CSF cholesterol in MS patients with positive OBs might reflect extensive demyelination and a more aggressive disease course associated with an increased humoral immune response against membrane components.

Expanding the spectrum of C9ORF72-related neurodegenerative disorders in the Greek population.

The C9ORF72 hexanucleotide repeat expansion is an established cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) and has also been associated with Huntington disease (HD)-like syndromes and rarely with Parkinson's disease (PD) and Alzheimer's disease (AD). In the present study we aimed to investigate the genotypic and phenotypic profile of C9ORF72-related disorders in Greece. For this reason, 957 patients (467 with ALS, 53 with HD-like syndromes, 247 with dementia, 175 with PD and 15 with hereditary spastic paraplegia, HSP) and 321 controls were tested for the C9ORF72 repeat expansion. Forty-nine patients with ALS (10.5%), 2 with HD-like syndromes (3.8%), 13 with FTD (11.5%), 1 with AD (1.6%), and 2 with PD (1.1%) were expansion-positive. The expansion was not detected in the HSP or control groups. The results of this study provide an update on the spectrum of C9ORF72-related neurodegenerative diseases, emphasizing the importance of C9ORF72 genetic testing in Greek patients with familial and sporadic ALS and/or FTD and HD-like syndromes.

High Hereditary Transthyretin-Related Amyloidosis Prevalence in Crete: Genetic Heterogeneity and Distinct Phenotypes.

Background and Objectives: Our goal was to study hereditary transthyretin-related amyloidosis (hATTR) in Crete, Greece. Methods: We aimed at ascertaining all hATTR cases in Crete, an island of 0.62 million people. For this, we evaluated patients with polyneuropathy, autonomic involvement, cardiomyopathy, and/or ophthalmopathy suggestive of hATTR, who presented to the physicians of this study or were referred to them by other physicians. Genetic analyses were performed on all patients suspected of suffering from hATTR. We included in our observational longitudinal cohort study all individuals, residents of Crete, who, during the study period (1993-2019), were found to carry a pathogenic TTR variant. Results: Over the past 27 years, 30 individuals (15 female patients, 15 male patients), from 12 apparently unrelated families, were diagnosed with hATTR, whereas evaluation of their offspring identified 5 asymptomatic TTR pathogenic variant carriers. The most prevalent TTR variant detected was p.Val50Met, affecting 19 patients (11 female patients, 8 male patients) and causing a rather consistent phenotype characterized by predominant polyneuropathy of early adult onset (median age of symptom onset: 30 years; range: 18-37 years). Specifically, patients affected by the p.Val50Met TTR variant experienced progressive sensorimotor disturbances, involving mainly the lower extremities, associated with autonomic and/or gastrointestinal dysfunction. The second most frequent TTR variant was p.Val114Ala, found in 10 patients (4 female patients, 6 male patients) who were affected at an older age (median age of symptom onset: 70 years; range: 54-78 years). This variant caused a predominantly cardiomyopathic phenotype, manifested by congestive heart failure and associated with peripheral neuropathy, carpal tunnel syndrome, and/or autonomic involvement. In these patients, cardiac amyloid deposition was detected on 99m-technetium pyrophosphate scintigraphy and/or heart biopsy. The third TTR variant (p.Arg54Gly) was found in a 50-year-old male patient with ophthalmopathy due to vitreous opacities and positive family history for visual loss. As 22 patients were alive at the end of the study, we calculated the hATTR prevalence in Crete to be 35 cases per 1 million inhabitants. Discussion: Our study revealed that the prevalence of hATTR in Crete is one of the world's highest. Three different pathogenic TTR variants causing distinct clinical phenotypes were identified in this relatively small population pool.

Prevalence and clinical outcomes of transthyretin amyloidosis: a systematic review and meta-analysis.

AIM: Systematic evidence on the prevalence and clinical outcome of transthyretin amyloidosis (ATTR) is missing. We explored: (i) the prevalence of cardiac amyloidosis in various patient subgroups, (ii) survival estimates for ATTR subtypes, and (iii) the effects of novel therapeutics on the natural course of disease. METHODS AND RESULTS: A systematic review of literature published in MEDLINE before 31 December 2021 was performed for the prevalence of cardiac amyloidosis and all-cause mortality of ATTR patients. Extracted data included sample size, age, sex, and all-cause mortality at 1, 2, and 5 years. Subgroup analyses were performed for ATTR subtype, that is, wild-type ATTR (wtATTR) versus hereditary ATTR (hATTR), hATTR genotypes, and treatment subgroups. We identified a total of 62 studies (n = 277 882 individuals) reporting the prevalence of cardiac amyloidosis, which was high among patients with a hypertrophic cardiomyopathy phenotype, heart failure with preserved ejection fraction, and the elderly with aortic stenosis. Data on ATTR mortality were extracted from 95 studies (n = 18 238 ATTR patients). Patients with wtATTR were older (p = 7 × 10-10 ) and more frequently male (p = 5 × 10-20 ) versus hATTR. The 2-year survival of ATTR was 73.3% (95% confidence interval [CI] 70.9-75.7); for non-subtyped ATTR 70.4% (95% CI 66.9-73.9), for wtATTR 76.0% (95% CI 73.0-78.9]) and for hATTR 77.2% (95% CI 74.0-80.4); in meta-regression analysis, wtATTR was associated with higher survival after adjusting for confounders. There was an interaction between survival and hATTR genotypes (p = 10-15 , Val30Met having the lowest and Val122Ile/Thr60Ala the highest mortality). ATTR 2-year survival was higher on tafamidis/patisiran compared to natural disease course (79.9%, 95% CI 74.4-85.3 vs. 72.4%, 95% CI 69.8-74.9, p < 0.05). CONCLUSIONS: We report the prevalence of ATTR in various population subgroups and provide survival estimates for the natural course of disease and the effects of novel therapeutics. Important gaps in worldwide epidemiology research in ATTR were identified.

HLA-genotyping by next-generation-sequencing reveals shared and unique HLA alleles in two patients with coexisting neuromyelitis optica spectrum disorder and thymectomized myasthenia gravis: Immunological implications for mutual aetiopathogenesis?

The exact immunopathogenesis, genetic mechanisms and triggering factors underlying myasthenia gravis (MG) and neuromyelitis optica (NMO) remain unknown and the coexistence may underline an aetiopathogenetic link be- tween these two diseases. We report the cases of two thymectomized patients with acetylcholine receptor (AChR) antibody (Ab)-positive MG who eventually developed AQP4-NMO. Next-Generation Sequencing (NGS) analysis showed that patient-1 had two HLA alleles previously associated with MG, mainly HLA-A*01:01:01 and HLA-DRB1*03:01, present in a haplotype in Caucasian MG patients (HLA-A1-B8-DR3-DQ2). Patient-2, expressed HLA-C*07:01:01, a well characterized MG risk factor and HLA-DQB1*05:02:01, previously described both in MG and NMO patients. Finally, we observed two common alleles in patient 1 and 2, HLA-DQA1*05:01:01 and HLA-DPB1*04:02:01. We believe that this study provides clinical evidence of the role of specific HLA alleles in rare forms of combined human peripheral and CNS autoimmunity, a fact that enhances the aim towards tailor-made therapeutic decision making.

Co-occurrence between hereditary angioedema and multiple sclerosis: Therapeutic management of both diseases with fingolimod.

BACKGROUND: Hereditary angioedema (HAE) related to C1 esterase-inhibitor deficiency activates the classic complement pathway and results to edematous crises. Although HAE is usually associated with multiple immunoregulatory disorders, neurologic manifestations are rare. CASE REPORT: We report on the case study of a 33-year-old man diagnosed with HAE (SERPIN1G gene mutation) and multiple sclerosis (MS), followed up for at least 6 years. After a first clinical attack of HEA with scrotal edema, MS disease exacerbation was observed. Treatment with glatiramer acetate could not prevent either MS or HAE clinical attacks with recurrent exacerbations been observed. Remission of MS and significant amelioration of HAE attacks were achieved under fingolimod treatment. CONCLUSIONS: Herein we provide long term evaluation of an extremely rare case of concomitant existence of HAE and MS and present the effects of MS current disease-modifying therapies in HAE attacks. Our case highlights the possible effect of fingolimod in immunoregulatory-mechanisms implicated in both diseases.

Structural and functional brain changes in X-linked Charcot-Marie-Tooth disease: insights from a multimodal neuroimaging study.

PURPOSE: Brain involvement in X-linked Charcot-Marie-Tooth disease (CMTX) has been previously reported. We studied the brain structural and functional integrity using a multimodal neuroimaging approach in patients with no current central nervous system (CNS) symptoms, in order to further delineate the disease's phenotype. METHODS: Seventeen CMTX patients with no current CNS symptoms and 24 matched healthy controls underwent brain magnetic resonance imaging (MRI). Structural integrity was evaluated performing Gray matter analysis with voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) of diffusion tensor imaging (DTI). Functional integrity was evaluated with resting-state functional MRI (rs-fMRI). RESULTS: Decreased gray matter density was detected in CMTX patients compared to healthy controls in bilateral hippocampus, left thalamus, left postcentral gyrus, left superior parietal lobule, left cerebellum crus I and II, and vermis VI. DTI analysis showed increased fractional anisotropy and radial diffusivity in the right anterior insula and increased axial diffusivity in right cerebellum crus I in CMTX patients. rs-fMRI revealed decreased spontaneous neural activity on left precentral gyrus in patients compared to healthy controls. CONCLUSION: Advanced magnetic resonance (MR) neuroimaging techniques in CMTX patients revealed structural and functional involvement of multiple motor and extra-motor brain areas. MR neuroimaging techniques have the potential to delineate the CNS phenotype of a peripheral neuropathy like CMTX.

Cortical involvement and leptomeningeal inflammation in myelin oligodendrocyte glycoprotein antibody disease: A three-dimensional fluid-attenuated inversion recovery MRI study.

BACKGROUND: Cortical demyelination and meningeal inflammation have been detected neuropathologically in multiple sclerosis (MS) and recently in myelin oligodendrocyte glycoprotein antibody disease (MOGAD). OBJECTIVES: To assess in vivo cortical and leptomeningeal involvement in MOGAD. METHODS: We prospectively evaluated 11 MOGAD and 12 relapsing-remitting MS (RRMS) patients combining three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) and 3D-T1-weighted (3D-T1w) sequences at 3-Tesla magnetic resonance imaging (MRI). Leptomeningeal contrast enhancement (LMCE) was assessed on 3D-FLAIR post-gadolinium (3D-FLAIRGd). Cerebral cortical lesions (CCLs) were classified as either intracortical-subpial (IC-SP) or leukocortical (LC). RESULTS: CCLs were present in 8/11 MOGAD and 12/12 RRMS patients, with the number of CCLs being significantly lower in MOGAD (median (interquartile range (IQR)) 3 (0.5-4) vs 12 (4.75-19), p = 0.0032). In MOGAD, IC-SP lesions were slightly more prevalent than LC lesions (2 (0-2.5) vs 1 (0-2), p = 0.6579); whereas in RRMS, IC-SP lesions were less prevalent than LC lesions (3.5 (2.75-5.5) vs 9 (2-12.75), p = 0.27). LMCE was observed in 3/11 MOGAD and 1/12 RRMS patients; MOGAD with LMCE showed an increased median number of CCLs compared with MOGAD without LMCE (8 (4-9) vs 2.5 (0.75-3.25), p = 0.34). No correlation was observed between MOGAD MRI findings and (a) MOGAD duration, (b) serum MOG-immunoglobulin G1 titers, and (c) oligoclonal band presence. CONCLUSION: We described cortical lesion topography and detected for the first time LMCE using 3D-FLAIRGd sequences in MOGAD patients.

Variant transthyretin amyloidosis (ATTRv) polyneuropathy in Greece: a broad overview with a focus on non-endemic unexplored regions of the country.

Comprehensive data on variant transthyretin amyloidosis polyneuropathy (ATTRv-PN) in Greece are lacking. We presently provide an overview of ATTRv-PN in Greece, focusing on unexplored non-endemic regions of the country. In total, we identified 57 cases of ATTRv-PN diagnosed over the past 25 years, including 30 from the island of Crete, an apparent endemic region. Patients carried 10 different TTR mutations (C10R; P24S; V30M; R34G; R34T; I68L; A81T; E89Q; E89K and V94A). Carriers of the common V30M mutation constituted 54.3 % of the cohort. A known founder effect for the V30M mutation was present on the island of Crete. Non-endemic cases identified outside the island of Crete are presently reported in more detail. The age of onset ranged from 25 to 77 years, with a mean of 51.1 years. A mean diagnostic delay of 3.2 years was observed. V30M patients had earlier onset and less cardiac involvement than patients carrying other mutations. Genotype-phenotype correlations were largely consistent with published data. We conclude that, with the exception of the Cretan cluster, ATTRv-PN is not endemic in the Greek population. This makes timely diagnosis more challenging, yet absolutely essential given the availability of therapies that can alter the long-term course of the disease.

IgG4-related autoimmune manifestations in Alemtuzumab-treated multiple sclerosis patients.

We aimed to determine whether Alemtuzumab-induced immune reconstitution affects immunoglobulin and complement levels in the serum of Relapsing-Remitting Multiple Sclerosis (RRMS) patients. IgG4-levels were increased 24-months after treatment initiation compared to baseline levels in twenty-nine patients. Alemtuzumab-treated patients with the highest IgG4-levels were more prone to thyroid-related autoimmune manifestations and specific autoimmune adverse events such as Crohn's disease, Graves' disease, and hemolytic anemia. Compared to baseline, total IgG-levels showed a trend towards reduced levels following two-courses of Alemtuzumab, but no significant change of C3 and/or C4-levels was observed. In conclusion, monitoring of IgG4-levels can serve as a marker for secondary autoimmunity risk in multiple sclerosis patients treated with Alemtuzumab.

HINT1-related neuropathy in Greek patients with Charcot-Marie-Tooth disease.

Autosomal recessive axonal neuropathy with neuromyotonia (ARAN-NM) is a rare hereditary neuropathy within the Charcot-Marie-Tooth disease (CMT) spectrum, linked to mutations in the histidine triad nucleotide-binding protein 1 (HINT1) gene. HINT1-related neuropathy is particularly common in selected populations from Central and Eastern Europe but rare in Western European cohorts. It has not been investigated to date in the Greek population. We presently investigated the frequency of HINT1-neuropathy in a selected cohort of 42 Greek index patients with autosomal recessive or sporadic axonal hereditary neuropathy according to standard molecular genetics procedures. We identified 4 patients with biallelic mutations in HINT1, comprising 9.5% of all cases and 44.4% of cases also displaying neuromyotonia. The c.110G> C (p.Arg37Pro) HINT1 mutation was present in all cases (2 homozygous) and the c.250T> C (p.Cys84Arg) in 2 cases (compound heterozygous). HINT1-related neuropathy patients were characterized by early onset and neuromyotonia. Two patients had noteworthy clinical features, one case developing myoclonic epilepsy and the other displaying "adducted thumbs." We conclude that HINT1-related neuropathy is common in selected Greek patients with hereditary neuropathy within the CMT spectrum, in accordance with some, but not all, European populations.

Genotyping and Plasma/Cerebrospinal Fluid Profiling of a Cohort of Frontotemporal Dementia-Amyotrophic Lateral Sclerosis Patients.

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are part of the same pathophysiological spectrum and have common genetic and cerebrospinal fluid (CSF) biomarkers. Our aim here was to identify causative gene variants in a cohort of Greek patients with FTD, ALS and FTD-ALS, to measure levels of CSF biomarkers and to investigate genotype-phenotype/CSF biomarker associations. In this cohort of 130 patients (56 FTD, 58 ALS and 16 FTD-ALS), we performed C9orf72 hexanucleotide repeat expansion analysis, whole exome sequencing and measurement of "classical" (Aß42, total tau and phospho-tau) and novel (TDP-43) CSF biomarkers and plasma progranulin. Through these analyses, we identified 14 patients with C9orf72 repeat expansion and 11 patients with causative variants in other genes (three in TARDBP, three in GRN, three in VCP, one in FUS, one in SOD1). In ALS patients, we found that levels of phospho-tau were lower in C9orf72 repeat expansion and MAPT c.855C>T (p.Asp285Asp) carriers compared to non-carriers. Additionally, carriers of rare C9orf72 and APP variants had lower levels of total tau and Aß42, respectively. Plasma progranulin levels were decreased in patients carrying GRN pathogenic variants. This study expands the genotypic and phenotypic spectrum of FTD/ALS and offers insights in possible genotypic/CSF biomarker associations.