Immunological study of hereditary motor and sensory neuropathy type 1a (HMSN1a)

Case report: Chronic inflammatory demyelinating polyneuropathy superimposed on Charcot-Marie-tooth type 1A disease after SARS-CoV-2 vaccination and COVID-19 infection

Background

There is growing evidence that severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) or COVID-19 infection is associated with the development of immune mediated neuropathies like chronic inflammatory demyelinating polyneuropathy (CIDP), but the impact of SARS-CoV-2 vaccination and COVID-19 infection on genetic disorders such as Charcot-MarieTooth (CMT) remains unclear.

Case presentation

A 42-year-old male with occulted CMT neuropathy type lA (CMT1A) who developed limb numbness and weakness after the second SARS-CoV-2-vaccination was confirmed by identifying characteristic repeats in the p11.2 region of chromosome 17. Due to the progressive deterioration of muscle strength over 8 weeks, limb atrophy, moderately elevated protein counts in the cerebrospinal fluid, and significant improvement with intravenous human immunoglobulin, which were characteristic of acquired inflammatory neuropathies, he was eventually diagnosed with CIDP superimposed on CMT1A. However, after a three-month plateau, the patient contracted COVID-19, which led to repeated and worsening symptoms of limb weakness and atrophy, thus was diagnosed with a recurrence of CIDP and treated with Intravenous immunoglobulin and methylprednisolone 500 mg/d for 5 consecutive days, followed by oral prednisone and mycophenolate mofetil tablets. On 2 month follow-up, he exhibited remarkable clinical improvement and could walk independently with rocking gait. After 1 year of follow-up, the patient's condition was stable without further change.

Conclusion

Our case indicates that CMT1A can deteriorate after SARS-CoV-2 vaccination. Thus, SARS-CoV-2 vaccination should be considered a potential predisposing factor for CMT1A worsening. The possible superposition of CMTIA and CIDP in the context of SARS-CoV-2 infection or immunity suggests that any clinical exacerbation in patients with CMT1A should be carefully evaluated to rule out treatable superposition inflammation. In addition, electrophysiological and imaging examination of the proximal nerves, such as the axillary nerve, is helpful for the diagnosis of CIDP.

A Rare Phenotype of Uncommon Charcot–Marie–Tooth Genotypes Complicated With Inflammation Evaluated by Genetics and Magnetic Resonance Neurography

The pathogenesis of Charcot–Marie–Tooth (CMT) disease, an inherited peripheral neuropathy, is associated with more than 60 nuclear genes. We reported a rare phenotype of the uncommon CMT genotype complicated with neuroinflammation, that is, an MPZ mutation, NC_000001.11 (NM_000530.6): c.308G > C detected by next-generation sequencing. Moreover, we present a case of the CMT type 1B, with atypical presentation as two patterns of hypertrophy in the brachial and lumbosacral plexus, as well as enhancement in the cauda equina and nerve roots on multimodal magnetic resonance neurography (MRN). MRN assessment facilitated the identification of coexisting neuroinflammation and provided more evidence, especially for patients with atypical symptoms in hereditary sensory and motor neuropathy, who could benefit from immunotherapy.

Inherited Neuromuscular Disorders: Which Role for Serum Biomarkers?

Inherited neuromuscular disorders (INMD) are a heterogeneous group of rare diseases that involve muscles, motor neurons, peripheral nerves or the neuromuscular junction. Several different lab abnormalities have been linked to INMD: sometimes they are typical of the disorder, but they usually appear to be less specific. Sometimes serum biomarkers can point out abnormalities in presymtomatic or otherwise asymptomatic patients (e.g., carriers). More often a biomarker of INMD is evaluated by multiple clinicians other than expert in NMD before the diagnosis, because of the multisystemic involvement in INMD. The authors performed a literature search on biomarkers in inherited neuromuscular disorders to provide a practical approach to the diagnosis and the correct management of INMD. A considerable number of biomarkers have been reported that support the diagnosis of INMD, but the role of an expert clinician is crucial. Hence, the complete knowledge of such abnormalities can accelerate the diagnostic workup supporting the referral to specialists in neuromuscular disorders.

hATTR Pathology: Nerve Biopsy Results from Italian Referral Centers

Pathological evidence of amyloid on nerve biopsy has been the gold standard for diagnosis in hereditary transthyretin amyloidosis polyneuropathy (hATTR-PN) for a long time. In this article, we reviewed the pathological findings of a large series of sural nerve biopsies from a cohort of hATTR-PN patients, collected by different Italian referral centers. Patients and Methods: We reviewed clinical and pathological data from hATTR-PN patients, diagnosed and followed in five Italian referral centers for peripheral neuropathies. Diagnosis was formulated after a positive genetic test for transthyretin (TTR) mutations. Sural nerve biopsy was performed according to standard protocols. Results: Sixty-nine sural nerve biopsies from hATTR-PN patients were examined. Congo red positive deposits were found in 73% of cases. Only the Phe64Leu mutation failed to show amyloid deposits in a high percentage of biopsies (54%), as already described. Unusual pathological findings, such as myelin abnormalities or inflammatory infiltrates, were detected in occasional cases. Conclusions: Even if no longer indicated to confirm hATTR-PN clinical suspicion, nerve biopsy remains, in expert hands, a rapid and inexpensive tool to detect amyloid deposition. In Italy, clinicians should be aware that a negative biopsy does not exclude hATTR-PN, particularly for Phe64Leu, one of the most frequent mutations in this country.

Genotypic and phenotypic spectrum of the most common causative genes of Charcot-Marie-Tooth disease in Hungarian patients

Charcot-Marie-Tooth neuropathy (CMT) is a genetically and clinically heterogeneous group of neuromuscular disorders with an overall prevalence of 1 per 2500. Here we report the first comprehensive genetic epidemiology study of Hungarian CMT patients. 409 CMT1 and 122 CMT2 patients were enrolled and genetic testing of PMP22, GJB1, MPZ, EGR2 and MFN2 genes were performed routinely. NDRG1 and CTDP1 genes were screened only for founder mutations in Roma patients. Causative genetic mutations were identified in 67.2% of the CMT1 and in 33.6% of the CMT2 cases, which indicates an overall success rate of 59.9% in the study population. Considering all affected individuals, alterations were most frequently found in PMP22 (40.5%), followed by GJB1 (9.2%), MPZ (4.5%), MFN2 (2.5%), NDRG1 (1.5%), EGR2 (0.8%) and CTDP1 (0.8%). The phenotypic spectrum and the disease severity of the studied patients also varied broadly. Deafness and autoimmune disorders were more often associated with PMP22 duplication, while MFN2 and GJB1 mutations were frequently present with central nervous system abnormalities. Our study may be helpful in determining the strategy of genetic diagnostics in Hungarian CMT patients.

Towards a functional pathology of hereditary neuropathies

A growing number of hereditary neuropathies have been assigned to causative gene defects in recent years. The study of human nerve biopsy samples has contributed substantially to the discovery of many of these neuropathy genes. Genotype-phenotype correlations based on peripheral nerve pathology have provided a comprehensive picture of the consequences of these mutations. Intriguingly, several gene defects lead to distinguishable lesion patterns that can be studied in nerve biopsies. These characteristic features include the loss of certain nerve fiber populations and a large spectrum of distinct structural changes of axons, Schwann cells and other components of peripheral nerves. In several instances the lesion patterns are directly or indirectly linked to the known functions of the mutated gene. The present review is designed to provide an overview on these characteristic patterns. It also considers other aspects important for the manifestation and pathology of hereditary neuropathies including the role of inflammation, effects of chemotherapeutic agents and alterations detectable in skin biopsies.

Hereditary and inflammatory neuropathies: a review of reported associations, mimics and misdiagnoses

Distinguishing between hereditary and inflammatory neuropathy is usually straightforward on clinical grounds with the help of a family history. There are nevertheless cases where the distinction is less clear. The advent of molecular genetics has in the past several years aided confirmatory diagnosis for an increasing proportion of patients with genetic neuropathy. Various reports have described associations of Charcot-Marie-Tooth disease with a suspected or confirmed inflammatory neuropathy occasionally responding to immunotherapy. Possible predisposition to an inflammatory component was suggested in a subset of patients. Such reports have, however, been relatively few in number, suggesting the rarity of such associations and of such a predisposition if it exists. There have been a number of publications detailing clinical presentations suggestive of inflammatory neuropathy in patients with a known or later proven genetic aetiology, and subsequently felt to be part of the phenotype rather than representing an association. A number of genetically mediated multisystemic diseases with neuropathy have otherwise been reported as mimicking chronic inflammatory demyelinating polyneuropathy (CIDP). The most common example is that of familial amyloid polyneuropathy, of particular concern for the clinician when misdiagnosed as CIDP, in view of the therapeutic implications. We review the literature on reported associations, mimics and misdiagnoses of hereditary and inflammatory neuropathy and attempt to determine a practical approach to the problem in clinical practice using clinical features, electrophysiology, histopathology and targeted early genetic testing. The issue of attempting immunomodulatory therapy is discussed in view of the published literature.

[Autopsy case of a patient with Charcot-Marie-Tooth disease type 1A and suspected chronic inflammatory demyelinating polyradiculoneuropathy, which was later diagnosed as amyotrophic lateral sclerosis]

We report an autopsy case of a 74-year-old man with late onset Charcot-Marie-Tooth disease type 1A (CMT1A) diagnosed by genetic screening, later associated with amyotrophic lateral sclerosis (ALS). At the age of 70 years, the patient was admitted to our hospital because of progressive weakness and dysesthesia in the right upper limb. In the early stages of the illness, he was diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and transient improvement was achieved with intravenous immunoglobulin. However, the symptoms progressively worsened and became refractory. Gene analysis revealed PMP22 gene duplication, which confirmed CMT1A. On sural nerve biopsy, severe demyelinating neuropathy and abundant onion-bulb formations with endoneurial infiltration of inflammatory cells were observed. Thereafter, pseudo-bulbar palsy and respiratory muscle weakness developed insidiously and progressed rapidly along with muscle weakness in the limbs and trunk. The patient died about four years after the onset of this disease. Postmortem examination showed moderate neuronal cell loss, Bunina bodies, and TDP-43-positive inclusions in the anterior horn cells. The spinal cord revealed axonal loss and extensive macrophage permeation in the corticospinal tracts. On the basis of these findings, the final neuropathological diagnosis was ALS. This is the first report of an autopsy case of CMT1A complicated with ALS. We here discuss the significant clinical and neuropathological findings of this case.

Beneficial use of steroids in hereditary neuropathy with liability to pressure palsy

Management of hereditary neuropathy with liability to pressure palsy (HNPP) is primarily conservative, aimed at preventing nerve injury by avoiding trauma or other potential aggravating factors. No pharmacological treatment is known to be beneficial. We describe two adolescents, one with HNPP (male; aged 15y) and another with a clinical picture suggestive of HNPP (genetically unconfirmed; female; aged 14y), who showed considerable improvement of their symptoms after receiving corticosteroid therapy. Both individuals were symptomatic for at least 5 months before the treatment. Following corticosteroids, both individuals demonstrated rapid improvement leading to near-complete recovery of muscle power. Clinical improvement after corticosteroid therapy has been reported in some individuals with other hereditary neuropathies. Our cases demonstrate that corticosteroid therapy may also be beneficial in individuals with HNPP who have a protracted or incomplete course of recovery.

Liver transplanted patients with preoperative autoimmune hepatitis and immunological disorders are at increased risk for Post-Transplant Lymphoproliferative Disease (PTLD)

BACKGROUND

Long term immunosuppression and therapy of acute rejections result in a 20-120-fold increased risk to develop Non Hodgkin lymphoma (NHL). Since immunosuppressive therapy and immunological disorders are major risk factors for the development of NHL in the non-transplant population we aimed to analyze risk factors for PTLD in our cohort of liver transplanted (LT) patients.

METHODS

We analyzed retrospectively 431 patients liver transplanted between 1998 and 2008.

RESULTS

PTLD was diagnosed in eleven of 431 patients (2.6%). PTLD, especially late PTLD, was significantly more frequent in patients who received steroids before LT (Kaplan-Meier: p<0.001). Moreover PTLD in immunocompromised patients with preoperative steroid treatment occurred at a significantly younger age (49.5+/-4.7 years) compared to patients without steroids (60.6+/-5.1 years; p=0.006). Multivariate analysis revealed pretransplant steroid treatment and liver transplantation for autoimmune hepatitis as main risk factors for the development of PTLD after liver transplantation (p<0.001).

CONCLUSION

Liver transplanted patients who received steroids before LT due to immunological disorders and patients with autoimmune hepatitis seem to be at particular high risk to develop PTLD. Prospective cohort studies including immunoepidemiologic investigations of abnormalities of cellular, humoral and innate immunity should be carried out to identify predictive factors and patients at risk.

Genetically determined neuropathy (CMT 1A) accompanied by immune dysfunction: a case report

Peripheral Myelin Protein 22 (PMP22) is mostly expressed in Schwann cells where it is essential in the compaction of myelin. The duplication of the PMP22 gene results in a hereditary demyelinating neuropathy of the Charcot-Marie-Tooth type 1A (CMT1A). So far there are only a few case reports suggesting that dysimmune mechanisms may take part in the pathophysiology of this disease. We describe three siblings carrying the duplication of the PMP22 gene, with a significant reduction of serum immunoglobulin G levels in all three cases and sural nerve vasculitis in the two women, which supports the proposition, that immune dysfunction may accompany this disease in some cases.

Severe Guillain–Barré syndrome associated with chromosome 17p11.2-12 duplication

We report a patient with Guillain-Barré syndrome (GBS), characterized by severe tetraparesis, bulbar syndrome, and ophthalmoparesis. The nadir was reached within 1 day, followed by respiratory insufficiency requiring mechanical ventilation. Molecular analysis revealed a duplication at chromosome 17p11.2-12, which is a known genetic cause of Charcot-Marie-Tooth disease type 1A (CMT1A). We suggest that this genotype may comprise a previously unrecognized genetic risk factor for GBS.

Study of antibodies to PMP22, IL-6 and TNF-alpha concentrations in serum in a CMTX1 family

To further understand X-linked dominant Charcot-Marie-Tooth disease (CMTX1), we followed a family of 22 members in China, including 8 patients, 2 asymptomatic carriers and 12 normal family members. Twenty-two family members as well as 60 normal controls unrelated to this family were screened for point mutation by denaturing high performance liquid chromatography (DHPLC). All patients and asymptomatic carriers from this family, but none of the normal population controls, showed a T-C transition at position 266 in codon 89 of exon 2 of connexin 32, resulting in a leucine to proline (L89P) exchange. To study whether the immune system is involved in the pathogenesis of CMTX1 patients and asymptomatic carriers, we measured serum concentrations of antibodies to peripheral nerve myelin protein 22 (PMP22), interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-alpha) by ELISA. Serological results were also compared with those from GBS patients (n=11) and with normal subjects (n=20). Our analysis showed anti-PMP22 sera reactivity in 50.0% of CMTX1 patients, 63.6% of GBS patients and 10% of normal controls. Our results also indicated that anti-PMP22 antibodies in the CMTX1 family varied with sex. Anti-PMP22 antibodies were found in all male patients but not in all females, which may be one of the reasons that male patients usually have more severe clinical symptoms than that of female patients. There was no statistical difference in serum concentrations of IL-6 and TNF-alpha between CMTX1 patients and normal subjects. In conclusion, we identified a L89P mutation for the first time in a CMTX1 family in China and an associated response to PMP22 in males.

Charcot-Marie-Tooth disease type 1A duplication: spectrum of clinical and magnetic resonance imaging features in leg and foot muscles

MRI is an ideal method for identifying areas of muscle atrophy and fatty infiltration. Studies comparing clinical and MRI features of foot and leg muscle atrophy in Charcot-Marie-Tooth disease type 1A (CMT-1A) duplication are lacking. The aim of this study is to describe clinical and MRI patterns of lower limb amyotrophy in CMT-1A. A total of 10 secondary CMT-1A patients and 1 proband patient with de novo mutation were prospectively evaluated. Ages of patients ranged from 8 to 61 years (median, 24). Disease severity in terms of ability to walk and run was established using a nine-point functional disability scale (FDS). We administered the CMT neuropathy score (CMTNS), based on patient's symptoms, neurological examination and neurophysiological testing. Muscle strength of flexo-extensor ankle and toe muscles was assessed manually with the standard Medical Research Council scale. In all 11 patients, leg MRI study included T1- and T2-weighted spin-echo sequences in coronal and axial planes, and a T1-weighted spin-echo sequence with chemical sift fat suppression before and after paramagnetic contrast agent injection. In seven patients both feet were simultaneously studied in coronal and axial planes. Six patients had pes cavus, an FDS score of 0 (normal), mild CMTNS and normal muscle power of foot flexo-extensors. In these six patients, MRI showed muscle fatty infiltration of intrinsic foot muscles mainly involving the lumbricals, all four leg muscle compartments being preserved. The remaining five patients had FDS scores from 1 (cramps or fatigability) to 3 (walking difficulty), mild to moderate CMTNS and variable weakness of peroneal musculature. In these five patients MRI showed, besides intrinsic foot muscle involvement, variable and distally accentuated fatty infiltration of the lateral, anterior and superficial posterior leg muscle compartments and, to a lesser degree, of the deep posterior compartment. In four patients muscle oedema and post-contrast enhancement was noted. MRI demonstrated fatty infiltration of clinically normal muscles. We conclude that clinical-MRI patterns of lower limb muscle atrophy vary with evolution of semiology. Selective involvement of intrinsic foot muscles is the characteristic pattern of CMT-1A cases with minimal disease signs. Afterwards this pattern usually combines variable involvement of leg muscles. Our findings help to clarity the pathogenesis of pes cavus in the disease.

Schwann cell overexpression of the GPR7 receptor in inflammatory and painful neuropathies

The human 7-transmembrane receptor GPR7 has sequence similarity to opioid and somatostatin receptors, and can be activated by the recently discovered neuropeptides NPB and NPW. This receptor is highly expressed in the nervous system, with suggested roles in neuroendocrine events and pain signaling. In this study, we investigated whether the GPR7 receptor is expressed in the peripheral nervous system under normal and pathological conditions. A low level of GPR7 receptor was observed in myelin-forming Schwann cells in both normal human and rat nerve, and in primary rat Schwann cell cultures. Peripheral nerve samples taken from patients exhibiting inflammatory/immune-mediated neuropathies showed a dramatic increase of GPR7 receptor expression restricted to myelin-forming Schwann cells. Complementary animal models of immune-inflammatory and ligation-induced nerve injury and neuropathic pain similarly exhibited an increased myelin-associated expression of GPR7 receptor. These results suggest a relationship between the pathogenesis of inflammatory/immune-mediated neuropathies, GPR7 receptor expression, and pain transmission.

Clinical disease severity and axonal dysfunction in hereditary motor and sensory neuropathy Ia

BACKGROUND

Hereditary motor and sensory neuropathy type Ia (HMSN Ia) is known as a primarily demyelinating peripheral nerve disease. Evidence is accumulating that axonal involvement determines the course of the disease process.

METHODS

Fifty-one patients were investigated. Physical disability and impairments were scored. Nerve conduction velocities (NCVs) were used as indirect measures for myelination status and compound muscle/sensory nerve action potential (CMAP/SNAP) amplitudes served as indirect measures for axonal function.

RESULTS

Median age was 39 years (range 6-69). Muscle weakness and sensory dysfunction was more severe in the legs than in the arms and distally more than proximally. However, more than 40% of the patients had proximal muscle weakness in the legs. Three point grip was used as representative of combined distal arm muscle groups. CMAP amplitude was the most important independent variable in a multiple linear regression model (forward selection) to explain the relation between three point grip strength and four different features, i. e., CMAP amplitude of the abductor pollicis brevis, median nerve MNCV, gender, and duration of signs and symptoms. The severity of axonal dysfunction was nerve length-dependent and was related to the myelination status. The mild physical disability due to both muscle weakness and sensory dysfunction was also related to axonal dysfunction.

CONCLUSIONS

In HMSN Ia, clinical disease severity at the impairment and disability levels is related to the severity of axonal dysfunction. Our data support the hypothesis that the myelination status is one of the factors that determine the extent of axonal dysfunction later in life. Proximal weakness of the legs is encountered in a considerable proportion of our patients.

Charcot-Marie-Tooth disease type 1A: clinicopathological correlations in 24 patients

We examined nerve biopsies from 24 patients with Charcot-Marie-Tooth disease type 1A (CMT1A) and proven 17p11.2-12 duplication. There were seven males and 17 females with a mean age of 27.85 +/- 18.95 years at the time of nerve biopsy. A family history consistent with dominant inheritance was present in 17 patients. Clinical features were classical in 16 patients and were atypical in the other eight: one had calf hypertrophy; two had Roussy-Levy syndrome; one had had a subacute inflammatory demyelinating polyneuropathy 11 years earlier and presented a relapse on the form of a chronic inflammatory demyelinating polyneuropathy; one had carpal tunnel syndrome; one had a recent painful neuropathy in both legs; and two had chronic inflammatory demyelinating polyneuropathy. Onion bulb formations (OMFs) were present in every case and most of them were characteristic, whereas burnt-out or cluster-associated OMFs were less common. Depletion of myelinated fibers was severe in 20 cases (169-2927/mm2) and varied from 5187 to 3725/mm2 in three children (4-9 years old). In addition, features of macrophage-associated demyelination were observed in the last four atypical cases. Known for more than 20 years, inflammatory demyelination superimposed in the course of CMT1A has been reported in a few cases in the past few years, mainly concerning asymptomatic or atypical patients. Such an association deserves to be better known because corticotherapy improves weakness in most of these patients.

Immune-mediated components of hereditary demyelinating neuropathies: lessons from animal models and patients

Most demyelinating forms of Charcot-Marie-Tooth type 1 (CMT1) neuropathy are slowly progressive and do not respond to anti-inflammatory treatment. In nerve biopsy samples, overt lymphocytic infiltration is absent, but pathological features typical of macrophage-related demyelination have been reported. In mouse models of CMT1, demyelination was substantially reduced when the mutants were backcrossed into an immunodeficient genetic background. A few individual patients with CMT1 respond to anti-inflammatory treatment; however, unlike most patients with CMT1, these patients show accelerated worsening of symptoms, inflammatory infiltrates in nerve biopsies, and clinical features resembling chronic inflammatory demyelinating polyneuropathy as well as CMT1. We conclude that in patients with typical CMT1 and in animal models, a cryptic and mild inflammatory process not responsive to standard anti-inflammatory treatment fosters genetically mediated demyelination.

Brain white matter lesions in an italian family with charcot-marie-tooth disease

Type 1A, the most common form of Charcot-Marie-Tooth (CMT1A) disease, is characterized by demyelination of the peripheral nervous system. So far, only a few cases of the disease with concomitant brain white matter lesions have been described. We report an Italian family with CMT1A disease, consisting of the proband and 4 affected members, presenting with concomitant brain white matter lesions at magnetic resonance imaging. The association is particularly fascinating and might depend on an autoimmune mechanism, not yet clarified.

Inflammatory demyelination in a patient with CMT1A

We report a case of Charcot-Marie-Tooth disease (CMT), with identified PMP22 gene duplication (CMT type 1A), and with evidence of an inflammatory demyelinating process superimposed on the course of the chronic genetic disease. Macrophage-associated demyelination was observed on the peripheral nerve biopsy. This observation supports some experimental data from the literature and shows that there may be a genetic susceptibility to inflammatory demyelinating processes in certain CMT kindreds.

Dejerine-Sottas syndrome grown to maturity: overview of genetic and morphological heterogeneity and follow-up of 25 patients

Dejerine-Sottas syndrome (DSS) is an early onset demyelinating motor and sensory neuropathy with motor nerve conduction velocities below 12 m s(-1). The phenotype is genetically heterogeneous, and autosomal dominant (AD) as well as autosomal recessive (AR) inheritance is described. Nerve pathology is highly variable. It is generally presumed that clinical course is severe, leading to wheelchair dependency at an early age. In this study we documented the clinical and pathological features in 25 patients with a DSS and we evaluated the clinical course. In our series 14 patients had an AD mutation and six were probably affected by an AR disorder. In three patients inheritance mode was unknown and two patients obviously suffered from an acquired disorder. The clinical course in all patients was documented. Nine of the 25 patients showed a moderate handicap in adult life; walking distance was still at least 1 km. Age at last investigation of the ambulant patients ranged from 22 to 62 years (mean 38.6 years), and ambulant patients were found in all genetic subgroups. We conclude that DSS, although in general denoting a more serious neuropathy than CMT1, does not imply a severe disability or wheelchair dependency in adult life.