Respiratory involvement and sleep-related disorders in CMT1A: case report and review of the literature

Sleep-disordered breathing has been reported in Charcot–Marie–Tooth disease (CMT) type 1A in association with diaphragmatic weakness and sleep apnea syndrome, mainly of the obstructive type (OSA). Improvement has been observed not only in sleep quality but also in neuropathy symptoms in CMT1A patients with OSA following the initiation of continuous positive airway pressure. We report the cases of two siblings affected by CMT1A associated with hemidiaphragm relaxatio necessitating nocturnal non-invasive ventilation (NIV). Two twins, now 42 years old, with a family history of CMT1A, received a genetic diagnosis of CMT1A at the age of 16. Over the years, they developed a slowly worsening gait disorder and a decline in fine motor hand movements, currently presenting with moderate disability (CMTES:13). At the age of 40, they both started complaining of daytime sleepiness, orthopnea, and exertional dyspnea. They received a diagnosis of relaxatio of the right hemidiaphragm associated with impairment of nocturnal ventilation and they both have benefited from nocturnal NIV. Disorders of breathing during sleep may be underestimated in CMT1A since routine investigations of sleep quality are rarely performed. Our two clinical cases and a literature review suggest the importance of inquiring about symptoms of excessive daytime sleepiness and respiratory disturbances in individuals with CMT1A, even in the absence of severe neuropathy. In the presence of compatible symptoms, a pneumological assessment, along with an overnight polysomnogram and lung function tests, should be performed. Recognizing sleep-related symptoms is essential for providing accurate treatment and improving the quality of life for patients with CMT1A

Charcot-Marie-Tooth Type 2B: A New Phenotype Associated with a Novel RAB7A Mutation and Inhibited EGFR Degradation

The rare autosomal dominant Charcot-Marie-Tooth type 2B (CMT2B) is associated with mutations in the RAB7A gene, involved in the late endocytic pathway. CMT2B is characterized by predominant sensory loss, ulceromutilating features, with lesser-to-absent motor deficits. We characterized clinically and genetically a family harboring a novel pathogenic RAB7A variant and performed structural and functional analysis of the mutant protein. A 39-year-old woman presented with early-onset walking diculties, progressive distal muscle wasting and weakness in lower limbs and only mild sensory signs. Electrophysiology demonstrated an axonal sensorimotor neuropathy. Nerve biopsy showed a chronic axonal neuropathy with moderate loss of all caliber myelinated fibers. Next-generation sequencing (NGS) technology revealed in the proband and in her similarly affected father the novel c.377A>G (p.K126R) heterozygous variant predicted to be deleterious. The mutation affects the biochemical properties of RAB7 GTPase, causes altered interaction with peripherin, and inhibition of neurite outgrowth, as for previously reported CMT2B mutants. However, it also shows differences, particularly in the epidermal growth factor receptor degradation process. Altogether, our findings indicate that this RAB7A variant is pathogenic and widens the phenotypic spectrum of CMT2B to include predominantly motor CMT2. Alteration of the receptor degradation process might explain the different clinical presentations in this family

Cross-sectional analysis of a large cohort with X-linked Charcot-Marie-Tooth disease (CMTX1).

OBJECTIVE: To extend the phenotypic description of Charcot-Marie-Tooth disease (CMTX1) and to draw new genotype-phenotype relationships. METHODS: Mutations in GJB1 cause the main X-linked form of CMTX (CMTX1). We report cross-sectional data from 160 patients (from 120 different families, with 89 different mutations) seen at the Inherited Neuropathies Consortium centers. RESULTS: We evaluated 87 males who had a mean age of 41 years (range 10-78 years) and 73 females who had a mean age of 46 years (range 15-84 years). Sensory-motor polyneuropathy affects both sexes, more severely in males than in females, and there was a strong correlation between age and disease burden in males but not in females. Compared with females, males had more severe reduction in motor and sensory neurophysiology parameters. In contrast to females, the radial nerve sensory response in older males tended to be more severely affected compared with younger males. Median and ulnar nerve motor amplitudes were also more severely affected in older males, whereas ulnar nerve motor potentials tended to be more affected in older females. Conversely, there were no statistical differences between the sexes in other features of the disease, such as problems with balance and hand dexterity. CONCLUSIONS: In the absence of a phenotypic correlation with specific GJB1 mutations, sex-specific distinctions and clinically relevant attributes need to be incorporated into the measurements for clinical trials in people with CMTX1. CLINICALTRIALSGOV IDENTIFIER: NCT01193075

Anxiety and depression in Charcot-Marie-Tooth disease: data from the Italian CMT national registry

Background There is little information about neuropsychiatric comorbidities in Charcot-Marie-Tooth disease (CMT). We assessed frequency of anxiety, depression, and general distress in CMT.Methods We administered online the Hospital Anxiety-Depression Scale (HADS) to CMT patients of the Italian registry and controls. HADS-A and HADS-D scores >= 11 defined the presence of anxiety/depression and HADS total score (HADS-T) >= 22 of general distress. We analysed correlation with disease severity and clinical characteristics, use of anxiolytics/antidepressants and analgesic/anti-inflammatory drugs.Results We collected data from 252 CMT patients (137 females) and 56 controls. CMT patient scores for anxiety (mean +/- standard deviation, 6.7 +/- 4.8), depression (4.5 +/- 4.0), and general distress (11.5 +/- 8.1) did not differ from controls and the Italian population. However, compared to controls, the percentages of subjects with depression (10% vs 2%) and general distress (14% vs 4%) were significantly higher in CMT patients. We found no association between HADS scores and disease duration or CMT type. Patients with general distress showed more severe disease and higher rate of positive sensory symptoms. Depressed patients also had more severe disease. Nineteen percent of CMT patients took antidepressants/anxiolytics (12% daily) and 70% analgesic/anti-inflammatory drugs. Patients with anxiety, depression, and distress reported higher consumption of anxiolytics/antidepressants. About 50% of patients with depression and/or general distress did not receive any specific pharmacological treatment.Conclusions An appreciable proportion of CMT patients shows general distress and depression. Both correlated with disease severity and consumption of antidepressants/anxiolytics, suggesting that the disease itself is contributing to general distress and depression

Novel ATP13A2 (PARK9) homozygous mutation in a family with marked phenotype variability

Mutations in the ATP13A2 (PARK9) and FBXO7 (PARK15) genes are linked to different forms of autosomal recessive juvenile-onset neurodegenerative diseases with overlapping phenotypes, including levodopa-responsive parkinsonism, pyramidal disturbances, cognitive decline, and supranuclear gaze disturbance. However, the associated genotypes and phenotypes are poorly characterized due to the small number of patients described. Here, we report clinical, instrumental, and genetic findings in an Italian family with novel PARK9 and PARK15 mutations. The proband developed a severe progressive phenotype including juvenile-onset parkinsonism, pyramidal disturbances, cognitive decline, and oculomotor abnormalities. On the contrary, his brother only shows mild abnormalities (pyramidal, cognitive, and oculomotor) on the neurological examination at the age of 31 years. These two brothers both carry a novel homozygous PARK9 missense (p.G877R) and a novel heterozygous PARK15 mutation (p.R481C). The PARK9 mutation replaces a crucial residue for the ATPase activity, and is therefore most likely a loss-of-function mutation and disease-causing in homozygous state. The pathogenic significance of the PARK15 single heterozygous mutation remains unclear. In both sibs, DaTSCAN single photon emission computed tomography showed marked nigrostriatal dopaminergic defects, and transcranial magnetic stimulation detected prolonged central motor conduction time. MRI, including T2*-weighted imaging, detected no evidence of brain iron accumulation. This family, the third reported with homozygous PARK9 mutations and the first with mutations in two genes for atypical juvenile parkinsonism, illustrates that PARK9-linked disease might display wide intra-familial clinical variability and milder phenotypes, suggesting the existence of strong, still unknown, modifiers

Absence of Dystrophin Related Protein-2 disrupts Cajal bands in a patient with Charcot-Marie-Tooth disease

Using exome sequencing in an individual with Charcot-Marie-Tooth disease (CMT) we have identified a mutation in the X-linked dystrophin-related protein 2 (DRP2) gene. A 60-year-old gentleman presented to our clinic and underwent clinical, electrophysiological and skin biopsy studies. The patient had clinical features of a length dependent sensorimotor neuropathy with an age of onset of 50 years. Neurophysiology revealed prolonged latencies with intermediate conduction velocities but no conduction block or temporal dispersion. A panel of 23 disease causing genes was sequenced and ultimately was uninformative. Whole exome sequencing revealed a stop mutation in DRP2, c.805C>T (Q269*). DRP2 interacts with periaxin and dystroglycan to form the periaxin-DRP2-dystroglycan complex which plays a role in the maintenance of the well-characterized Cajal bands of myelinating Schwann cells. Skin biopsies from our patient revealed a lack of DRP2 in myelinated dermal nerves by immunofluorescence. Furthermore electron microscopy failed to identify Cajal bands in the patient's dermal myelinated axons in keeping with ultrastructural pathology seen in the Drp2 knockout mouse. Both the electrophysiologic and dermal nerve twig pathology support the interpretation that this patient's DRP2 mutation causes characteristic morphological abnormalities recapitulating the Drp2 knockout model and potentially represents a novel genetic cause of CMT

Genetic analysis and natural history of Charcot-Marie-Tooth disease CMTX1 due to GJB1 variants

Charcot-Marie-Tooth disease (CMT) due to GJB1 variants (CMTX1) is the second most common form of CMT. It is an X-linked disorder characterised by progressive sensory and motor neuropathy with males affected more severely than females. Many reported GJB1 variants remain classified as variants of uncertain significance (VUS). In this large, international, multicentre study we prospectively collected demographic, clinical and genetic data on patients with CMT associated with GJB1 variants. Pathogenicity for each variant was defined using adapted American College of Medical Genetics criteria. Baseline and longitudinal analyses were conducted to study genotype-phenotype correlations, to calculate longitudinal change using the CMT Examination Score (CMTES), to compare males versus females, and pathogenic/likely pathogenic (P/LP) variants versus VUS. We present 387 patients from 295 families harbouring 154 variants in GJB1. Of these, 319 patients (82.4%) were deemed to have P/LP variants, 65 had VUS (16.8%) and 3 benign variants (0.8%; excluded from analysis); an increased proportion of patients with P/LP variants compared with using ClinVar's classification (74.6%). Male patients (166/319, 52.0%, P/LP only) were more severely affected at baseline. Baseline measures in patients with P/LP variants and VUS showed no significant differences, and regression analysis suggested the disease groups were near identical at baseline. Genotype-phenotype analysis suggested c.-17G>A produces the most severe phenotype of the five most common variants, and missense variants in the intracellular domain are less severe than other domains. Progression of disease was seen with increasing CMTES over time up to 8 years follow-up. Standard response mean (SRM), a measure of outcome responsiveness, peaked at 3 years with moderate responsiveness (change in CMTES (ΔCMTES) = 1.3 ± 2.6, p = 0.00016, SRM = 0.50). Males and females progressed similarly up to 8 years, but baseline regression analysis suggested that over a longer period, females progress more slowly. Progression was most pronounced for mild phenotypes (CMTES = 0-7; 3-year ΔCMTES = 2.3 ± 2.5, p = 0.001, SRM = 0.90). Enhanced variant interpretation has yielded an increased proportion of GJB1 variants classified as P/LP and will aid future variant interpretation in this gene. Baseline and longitudinal analysis of this large cohort of CMTX1 patients describes the natural history of the disease including the rate of progression; CMTES showed moderate responsiveness for the whole group at 3 years and higher responsiveness for the mild group at 3, 4 and 5 years. These results have implications for patient selection for upcoming clinical trials

Normal and pathogenic variation of RFC1 repeat expansions: implications for clinical diagnosis

Cerebellar Ataxia, Neuropathy and Vestibular Areflexia Syndrome (CANVAS) is an autosomal recessive neurodegenerative disease, usually caused by biallelic AAGGG repeat expansions in RFC1. In this study, we leveraged whole genome sequencing (WGS) data from nearly 10,000 individuals recruited within the Genomics England sequencing project to investigate the normal and pathogenic variation of the RFC1 repeat. We identified three novel repeat motifs, AGGGC (n=6 from 5 families), AAGGC (n=2 from 1 family), AGAGG (n=1), associated with CANVAS in the homozygous or compound heterozygous state with the common pathogenic AAGGG expansion. While AAAAG, AAAGGG and AAGAG expansions appear to be benign, here we show a pathogenic role for large AAAGG repeat configuration expansions (n=5). Long read sequencing was used to fully characterise the entire repeat sequence and revealed a pure AGGGC expansion in six patients, whereas the other patients presented complex motifs with AAGGG or AAAGG interruptions. All pathogenic motifs seem to have arisen from a common haplotype and are predicted to form highly stable G quadruplexes, which have been previously demonstrated to affect gene transcription in other conditions. The assessment of these novel configurations is warranted in CANVAS patients with negative or inconclusive genetic testing. Particular attention should be paid to carriers of compound AAGGG/AAAGG expansions, since the AAAGG motif when very large (>500 repeats) or in the presence of AAGGG interruptions. Accurate sizing and full sequencing of the satellite repeat with long read is recommended in clinically selected cases, in order to achieve an accurate molecular diagnosis and counsel patients and their families

A geo-chemo-mechanical study of a highly polluted marine system (Taranto, Italy) for the enhancement of the conceptual site model

The paper presents the results of the analysis of the geo-chemo-mechanical data gathered through an innovative multidisciplinary investigation campaign in the Mar Piccolo basin, a heavily polluted marine bay aside the town of Taranto (Southern Italy). The basin is part of an area declared at high environmental risk by the Italian government. The cutting-edge approach to the environmental characterization of the site was promoted by the Special Commissioner for urgent measures of reclamation, environmental improvements and redevelopment of Taranto and involved experts from several research fields, who cooperated to gather a new insight into the origin, distribution, mobility and fate of the contaminants within the basin. The investigation campaign was designed to implement advanced research methodologies and testing strategies. Differently from traditional investigation campaigns, aimed solely at the assessment of the contamination state within sediments lying in the top layers, the new campaign provided an interpretation of the geo-chemo-mechanical properties and state of the sediments forming the deposit at the seafloor. The integrated, multidisciplinary and holistic approach, that considered geotechnical engineering, electrical and electronical engineering, geological, sedimentological, mineralogical, hydraulic engineering, hydrological, chemical, geochemical, biological fields, supported a comprehensive understanding of the influence of the contamination on the hydro-mechanical properties of the sediments, which need to be accounted for in the selection and design of the risk mitigation measures. The findings of the research represent the input ingredients of the conceptual model of the site, premise to model the evolutionary contamination scenarios within the basin, of guidance for the environmental risk management. The study testifies the importance of the cooperative approach among researchers of different fields to fulfil the interpretation of complex polluted eco-systems

Twelve Variants Polygenic Score for Low-Density Lipoprotein Cholesterol Distribution in a Large Cohort of Patients With Clinically Diagnosed Familial Hypercholesterolemia With or Without Causative Mutations

: Background A significant proportion of individuals clinically diagnosed with familial hypercholesterolemia (FH), but without any disease-causing mutation, are likely to have polygenic hypercholesterolemia. We evaluated the distribution of a polygenic risk score, consisting of 12 low-density lipoprotein cholesterol (LDL-C)-raising variants (polygenic LDL-C risk score), in subjects with a clinical diagnosis of FH. Methods and Results Within the Lipid Transport Disorders Italian Genetic Network (LIPIGEN) study, 875 patients who were FH-mutation positive (women, 54.75%; mean age, 42.47±15.00 years) and 644 patients who were FH-mutation negative (women, 54.21%; mean age, 49.73±13.54 years) were evaluated. Patients who were FH-mutation negative had lower mean levels of pretreatment LDL-C than patients who were FH-mutation positive (217.14±55.49 versus 270.52±68.59 mg/dL, P<0.0001). The mean value (±SD) of the polygenic LDL-C risk score was 1.00 (±0.18) in patients who were FH-mutation negative and 0.94 (±0.20) in patients who were FH-mutation positive (P<0.0001). In the receiver operating characteristic analysis, the area under the curve for recognizing subjects characterized by polygenic hypercholesterolemia was 0.59 (95% CI, 0.56-0.62), with sensitivity and specificity being 78% and 36%, respectively, at 0.905 as a cutoff value. Higher mean polygenic LDL-C risk score levels were observed among patients who were FH-mutation negative having pretreatment LDL-C levels in the range of 150 to 350 mg/dL (150-249 mg/dL: 1.01 versus 0.91, P<0.0001; 250-349 mg/dL: 1.02 versus 0.95, P=0.0001). A positive correlation between polygenic LDL-C risk score and pretreatment LDL-C levels was observed among patients with FH independently of the presence of causative mutations. Conclusions This analysis confirms the role of polymorphisms in modulating LDL-C levels, even in patients with genetically confirmed FH. More data are needed to support the use of the polygenic score in routine clinical practice