Clinical practice guidelines for the diagnosis and management of Charcot-Marie-Tooth disease.

INTRODUCTION: Charcot-Marie-Tooth disease (CMT) is classified according to neurophysiological and histological findings, the inheritance pattern, and the underlying genetic defect. The objective of these guidelines is to offer recommendations for the diagnosis, prognosis, follow-up, and treatment of this disease in Spain. MATERIAL AND METHODS: These consensus guidelines were developed through collaboration by a multidisciplinary panel encompassing a broad group of experts on the subject, including neurologists, paediatric neurologists, geneticists, physiatrists, and orthopaedic surgeons. RECOMMENDATIONS: The diagnosis of CMT is clinical, with patients usually presenting a common or classical phenotype. Clinical assessment should be followed by an appropriate neurophysiological study; specific recommendations are established for the parameters that should be included. Genetic diagnosis should be approached sequentially; once PMP22 duplication has been ruled out, if appropriate, a next-generation sequencing study should be considered, taking into account the limitations of the available techniques. To date, no pharmacological disease-modifying treatment is available, but symptomatic management, guided by a multidiciplinary team, is important, as is proper rehabilitation and orthopaedic management. The latter should be initiated early to identify and improve the patient's functional deficits, and should include individualised exercise guidelines, orthotic adaptation, and assessment of conservative surgeries such as tendon transfer. The follow-up of patients with CMT is exclusively clinical, and ancillary testing is not necessary in routine clinical practice.

Altered myogenesis and premature senescence underlie human TRIM32-related myopathy.

TRIM32 is a E3 ubiquitin -ligase containing RING, B-box, coiled-coil and six C-terminal NHL domains. Mutations involving NHL and coiled-coil domains result in a pure myopathy (LGMD2H/STM) while the only described mutation in the B-box domain is associated with a multisystemic disorder without myopathy (Bardet-Biedl syndrome type11), suggesting that these domains are involved in distinct processes. Knock-out (T32KO) and knock-in mice carrying the c.1465G > A (p.D489N) involving the NHL domain (T32KI) show alterations in muscle regrowth after atrophy and satellite cells senescence. Here, we present phenotypical description and functional characterization of mutations in the RING, coiled-coil and NHL domains of TRIM32 causing a muscle dystrophy. Reduced levels of TRIM32 protein was observed in all patient muscle studied, regardless of the type of mutation (missense, single amino acid deletion, and frameshift) or the mutated domain. The affected patients presented with variable phenotypes but predominantly proximal weakness. Two patients had symptoms of both muscular dystrophy and Bardet-Biedl syndrome. The muscle magnetic resonance imaging (MRI) pattern is highly variable among patients and families. Primary myoblast culture from these patients demonstrated common findings consistent with reduced proliferation and differentiation, diminished satellite cell pool, accelerated senescence of muscle, and signs of autophagy activation.

A study of the neuropathy associated with transthyretin amyloidosis (ATTR) in the UK.

BACKGROUND: Hereditary transthyretin amyloidosis (ATTR) is usually characterised by a progressive peripheral and autonomic neuropathy often with associated cardiac failure and is due to dominantly inherited transthyretin mutations causing accelerated amyloid deposition. The UK population is unique in that the majority of patients have the T60A missense mutation in ATTR where tyrosine is replaced by adenine at position 60. This has been traced to a single founder mutation from north-west Ireland. The neuropathy phenotype is less well described than the cardiac manifestations in this group. METHODS: We present the findings from an observational cohort study of patients with ATTR attending the National Hospital Inherited Neuropathy Clinic between 2009 and 2013. Detailed clinical neurological and electrophysiological data were collected on all patients alongside correlating autonomic and cardiac assessments. Follow-up data were available on a subset. RESULTS: Forty-four patients with genetically confirmed ATTR were assessed; 37 were symptomatic; mean age at onset=62 years, range=38-75 years; 75.7% male. T60A was the most common mutation (17/37), followed by V30M (5/37). A severe, rapidly progressive, predominantly length dependent axonal sensorimotor neuropathy was the predominant phenotype. T60A patients were distinguished by earlier and more frequent association with carpal tunnel syndrome; a predominance of negative sensory symptoms at onset; significant vibration deficits; and a non-length dependent progression of motor deficit. Progression of the neuropathy was observed over a relatively short follow-up period (2 years) in 20 patients with evidence of clinically measurable annual change in Medical Research Council (MRC) sum score (-1.5 points per year) and Charcot Marie Tooth Neuropathy Score (CMTNS:2.7 points per year), and a congruent trend in the electrophysiological measures used. CONCLUSION: The description of the ATTR neuropathy phenotype, especially in the T60A patients, should aid early diagnosis as well as contribute to the understanding of its natural history.

Transthyretin V122I amyloidosis with clinical and histological evidence of amyloid neuropathy and myopathy.

Hereditary transthyretin amyloidosis (ATTR) is a genetically and clinically heterogeneous disease manifesting with predominant peripheral and autonomic neuropathy; cardiomyopathy, or both. ATTR V122I is the most common variant associated with non-neuropathic familial amyloid cardiomyopathy. We present an unusual case of V122I amyloidosis with features of amyloid neuropathy and myopathy, supported by histological confirmation in both sites and diffuse tracer uptake on (99m)Tc-3,3-Diphosphono-1,2-Propanodicarboxylic acid (DPD) scintigraphy throughout skeletal and cardiac muscle. A 64 year old Jamaican man presented with cardiac failure. Cardiac MR revealed infiltrative cardiomyopathy; abdominal fat aspirate confirmed the presence of amyloid, and he was homozygous for the V122I variant of transthyretin. He also described general weakness and EMG demonstrated myopathic features. Sural nerve and vastus lateralis biopsy showed TTR amyloid. The patient is being treated with diflunisal, an oral TTR stabilising agent. Symptomatic myopathy and neuropathy with confirmation of tissue amyloid deposition has not previously been described. Extracardiac amyloidosis has implications for diagnosis and treatment.

[Guidelines for molecular diagnosis of Charcot-Marie-Tooth disease]. / Guía diagnóstica en el paciente con enfermedad de Charcot-Marie-Tooth.

INTRODUCTION: Charcot-Marie-Tooth disease (CMT) is the most frequent form of inherited neuropathy. In accordance with the inheritance pattern and degree of slowing of motor conduction velocity (MCV) of the median nerve, CMT encompasses five main forms: CMT1 (autosomal dominant [AD] or X-linked transmission and MCV < 38 m/s); CMT2 (AD or X-linked transmission and MCV > 38 m/s); CMT4 (autosomal recessive [AR] and severe slowing of MCV); AR-CMT2 (AR transmission and MCV > 38 m/s); and DI-CMT (intermediate form with AD transmission and MCV between 30 and 40 m/s). In spite of its stereotyped semiological repertoire (basically, symptoms and signs of sensory-motor polyneuropathy and pes cavus), CMT seems to be one of the most complex hereditary neurodegenerative syndromes, 31 causative genes having been cloned. DEVELOPMENT: This paper is aimed at performing a nosological review of the disease, emphasising the guidelines for its molecular diagnosis. Genetic epidemiological studies and genotypes reported in Spanish patients are revised. CONCLUSIONS: In the great majority of CMT cases, mutations involve a reduced number of genes, namely: for CMT1, PMP22, GJB1 and MPZ; for CMT2, MFN2 and GJB1; for CMT4, GDAP1, and NDRG1, HK1 and SH3TC2 (gypsies); for AR-CMT2, GDAP1; and for DI-CMT, GJB1 and MPZ. Given their low prevalence, mutations in other pathogenic genes should be investigated after discarding the previous ones. There is no place for the indiscriminate use of diagnostic CMT genetic panels.