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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., (© 2023 Peripheral Nerve Society.)

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., (© 2021 Peripheral Nerve Society.)

Despite its widespread use, little is known regarding the ability of the semi-quantitative Rydel-Seiffer tuning fork to designate peripheral nerve function. We sought to determine in a large sample of normal and abnormal nerves the relationship between vibration sense and compound sensory nerve action potential (SNAP) parameters recorded in a corresponding innervation area. Vibratory thresholds were determined on a scale of 0 to 8 with a 64 Hz Rydel-Seiffer tuning fork placed on the lateral malleolus of 303 subjects. Sural nerve sensory neurography was employed to derive SNAP parameters, which were related to vibration sense by means of multiple linear regression. ROC curve analysis was performed to determine the classification efficacy of the tuning fork in distinguishing normal from abnormal sural nerve responses. SNAP amplitude was the most significant predictor in the whole subjects group and in the subgroup of subjects with normal SNAPs, whereas conduction velocity played a major role in subjects with abnormal SNAPs. Age was significantly associated with vibration perception, particularly in subjects with normal SNAPs. With an area under the curve of 0.730, vibration sense was a fair classifier for decreased SNAP amplitudes. The optimal vibratory cutoff was 4.2. Age is a major determinant of vibratory test results, highlighting the importance of aging of central and peripheral pathways in mediating vibration sense. Hence, neurophysiological testing cannot be omitted in the context of polyneuropathy work-up, since even at the optimal cutoff threshold, vibratory examination still displays 40% false negative test results., (© 2020 Peripheral Nerve Society.)

There has been limited information from population studies regarding the overall frequency of the common 1.5-Mb 17p11.2 deletion and even scarcer data regarding the overall frequency of PMP22 micromutations in patients with a clinical suspicion of hereditary neuropathy with liability to pressure palsies (HNPP). We have analysed 100 consecutive Greek patients referred for HNPP genetic testing over a 15-year period to our Neurogenetics Unit in Athens, a reference centre for all regions of Greece. All patients were screened for the 1.5-Mb deletion and a selected subgroup of deletion-negative patients for PMP22 micromutations. Mutation-positive and mutation-negative patients were compared for various clinical parameters. In total, 54 mutation-positive patients were identified. In index cases, the deletion frequency was 47.8%, and the PMP22 micromutation frequency was 2.2%. Within mutation-positive patients, the common deletion represented 95.7% and PMP22 micromutations 4.3% of cases. Two previously reported PMP22 micromutations (c.364_365delCC and c.79-2A>G) were detected. HNPP index cases had a 2.8-1 male-to-female ratio, similar to mutation-negative patients. A typical phenotype (recurrent or isolated palsies) was present in 82.4% of symptomatic HNPP cases, significantly higher than mutation-negative patients. Sensitivity of proposed electrophysiological diagnostic criteria for HNPP was calculated at 95.7% and specificity at 80.5%. In conclusion, the common HNPP deletion accounts for ∼50% and PMP22 micromutations for ∼2% of cases in a large consecutive cohort of patients with suspected HNPP. The mutational and phenotypic spectrum of HNPP is similar in the Greek population compared with other populations. Proposed electrophysiological diagnostic criteria perform satisfactorily in everyday clinical practice., (© 2015 Peripheral Nerve Society.)

The aim of this study was to compare Bangladeshi immigrants with diabetes to native Greeks with diabetes and to distinguish the different risk factors for polyneuropathy (PN) in the two ethnic groups. Subjects were recruited from the outpatient diabetic clinic of a general hospital. A total of 111 Bangladeshi immigrants (97 men and 14 women of mean age 47 years) and 101 native Greeks (82 men and 19 women of mean age 49 years) were included in the study. Sex, mean age, age at diabetes diagnosis, and diabetes duration did not differ between the two groups. PN was diagnosed in 53 (48%) Bangladeshi and in 59 (58%) Greek patients (p = 0.12). Large fiber neuropathy was less prevalent among Bangladeshis (18%) than in Greeks (53%) (p < 0.01). Small fiber neuropathy on the contrary were more frequent in Bangladeshis (18% vs. 7%) (p < 0.02). Regarding the risk factors for PN, Greek patients were taller, with higher BMI, and smoked more cigarettes (p < 0.001). They were also treated with more anti-lipid and antihypertensive agents. The higher percentage of SFN in Bangladeshi was mainly a result of the significantly greater incidence of erectile dysfunction (ED) in their group (68 Bangladeshi vs. 38 Greek men). It is well known that there are many causes of ED aside from SFN which were not evaluated in this study. Thus this conclusion should be taken with caution., (© 2015 Peripheral Nerve Society.)

The aim of the present study was to evaluate the occurrence of large and small fiber neuropathy among alcohol-dependent subjects and to correlate neuropathy with the pattern of alcohol abuse, age of the subjects, nutritional status, and biochemical parameters. The study sample comprised 98 consecutive alcohol-dependent subjects without signs of malnutrition treated for detoxification voluntarily in the specialized unit of the Athens University Psychiatric Clinic in an inpatient basis. Polyneuropathy (PN) was graded using the neuropathy symptoms score and neurologic disability score, conduction velocity studies, and quantitative sensory tests. Seventy-seven men and 21 women aged 27-70 years took part in the study. PN was diagnosed in 57 subjects (58.2%). PN of both large and small fibers was found in 25 patients (25.5%); exclusively small fiber neuropathy was observed in 12 (12.2%) and exclusively large fiber neuropathy in 20 patients (20.4%). Neuropathy was significantly correlated with the age of the subjects, duration of alcohol abuse, liver dysfunction, macrocytosis, and blood sugar levels upon admission. PN was significantly more frequent in males than in females. The two groups of exclusively large and exclusively small fiber neuropathy did not differ significantly in any clinical and laboratory parameter. Subclinical neuropathy (stage 1) was observed in 11.2%, which also did not differ significantly in any clinical and laboratory parameter from the stage 2 PN group subjects. Our findings indicate the direct toxic effect of alcohol on peripheral nerve fibers as the main etiologic factor of alcoholic PN. Long-standing hyperglycemia may be another contributing factor. Impaired vitamin B(12) utilization may be also involved.