RESUMEN
BACKGROUND AND PURPOSE: Charcot-Marie-Tooth disease type 1 (CMT1) is a group of autosomal dominantly inherited demyelinating sensorimotor neuropathies. Symptoms usually start in the first to second decade and include distal muscle weakness and wasting, sensory disturbances and foot deformities. The most frequent cause is a duplication of PMP22 whilst point mutations in PMP22 and other genes are rare causes. Recently, FBLN5 mutations have been reported in CMT1 families. METHODS: Individuals with FBLN5-associated CMT1 were compiled from clinical and research genetic testing laboratories. Clinical data were extracted from medical records or obtained during patients' visits at our centres or primary care sites. RESULTS: Nineteen CMT1 families containing 38 carriers of three different FBLN5 missense variants were identified and a mutational hotspot at c.1117C>T (p.Arg373Cys) was confirmed. Compared to patients with the common PMP22 duplication, individuals with FBLN5 variants had a later age of diagnosis (third to fifth decade) and less severely reduced motor median nerve conduction velocities (around 31 m/s). The most frequent clinical presentations were prominent sensory disturbances and painful sensations, often as initial symptom and pronounced in the upper limbs, contrasting with rather mild to moderate motor deficits. CONCLUSIONS: Our study confirms the relevance of FBLN5 mutations in CMT1. It is proposed to include FBLN5 in the genetic work-up of individuals suspected with CMT1, particularly when diagnosis is established beyond the first and second decade and comparably moderate motor deficits contrast with early and marked sensory involvement. FBLN5-associated CMT1 has a recognizable clinical phenotype and should be referred to as CMT1H according to the current classification scheme.
Asunto(s)
Enfermedad de Charcot-Marie-Tooth/genética , Proteínas de la Matriz Extracelular/genética , Pruebas Genéticas , Humanos , Mutación , FenotipoRESUMEN
BACKGROUND: Peripheral nerve stimulation is commonly used for nerve localization in regional anaesthesia, but recommended stimulation currents of 0.3-0.5 mA do not reliably produce motor activity in the absence of intraneural needle placement. As this may be particularly true in patients with diabetic neuropathy, we examined the stimulation threshold in patients with and without diabetes. METHODS: Preoperative evaluation included a neurological exam and electroneurography. During ultrasound-guided popliteal sciatic nerve block, we measured the current required to produce motor activity for the tibial and common peroneal nerve in diabetic and non-diabetic patients. Proximity to the nerve was evaluated post-hoc using ultrasound imaging. RESULTS: Average stimulation currents did not differ between diabetic (n=55) and non-diabetic patients (n=52). Although the planned number of patients was not reached, the power goal for the mean stimulation current was met. Subjects with diminished pressure perception showed increased thresholds for the common peroneal nerve (median 1.30 vs. 0.57 mA in subjects with normal perception, P=0.042), as did subjects with decreased pain sensation (1.60 vs. 0.50 mA in subjects with normal sensation, P=0.038). Slowed ulnar nerve conduction velocity predicted elevated mean stimulation current (r=-0.35, P=0.002). Finally, 15 diabetic patients required more than 0.5 mA to evoke a motor response, despite intraneural needle placement (n=4), or required currents ≥2 mA despite needle-nerve contact, vs three such patients (1 intraneural, 2 with ≥2 mA) among non-diabetic patients (P=0.003). CONCLUSIONS: These findings suggest that stimulation thresholds of 0.3-0.5 mA may not reliably determine close needle-nerve contact during popliteal sciatic nerve block, particularly in patients with diabetic neuropathy. CLINICAL TRIAL REGISTRATION: NCT01488474.
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Neuropatías Diabéticas/fisiopatología , Estimulación Eléctrica , Bloqueo Nervioso/métodos , Nervio Ciático , Adulto , Anciano , Anciano de 80 o más Años , Potenciales Evocados Motores/efectos de los fármacos , Femenino , Estudios de Seguimiento , Humanos , Extremidad Inferior/cirugía , Masculino , Persona de Mediana Edad , Conducción Nerviosa/efectos de los fármacos , Procedimientos Ortopédicos , Percepción del Dolor/efectos de los fármacos , Nervio Peroneo/efectos de los fármacos , Nervio Ciático/diagnóstico por imagen , Umbral Sensorial , Nervio Tibial/efectos de los fármacos , Ultrasonografía IntervencionalRESUMEN
Hereditary sensory neuropathy type I (HSN1) is the most common hereditary disorder of peripheral sensory neurons. HSN1 is an autosomal dominant progressive degeneration of dorsal root ganglia and motor neurons with onset in the second or third decades. Initial symptoms are sensory loss in the feet followed by distal muscle wasting and weakness. Loss of pain sensation leads to chronic skin ulcers and distal amputations. The HSN1 locus has been mapped to chromosome 9q22.1-22.3 (refs. 3,4). Here we map the gene SPTLC1, encoding serine palmitoyltransferase, long chain base subunit-1, to this locus. Mutation screening revealed 3 different missense mutations resulting in changes to 2 amino acids in all affected members of 11 HSN1 families. We found two mutations to be located in exon 5 (C133Y and C133W) and one mutation to be located in exon 6 of SPTLC1 (V144D). All families showing definite or probable linkage to chromosome 9 had mutations in these two exons. These mutations are associated with increased de novo glucosyl ceramide synthesis in lymphoblast cell lines in affected individuals. Increased de novo ceramide synthesis triggers apoptosis and is associated with massive cell death during neural tube closure, raising the possibility that neural degeneration in HSN1 is due to ceramide-induced apoptotic cell death.
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Aciltransferasas/genética , Neuropatías Hereditarias Sensoriales y Autónomas/enzimología , Neuropatías Hereditarias Sensoriales y Autónomas/genética , Mutación , Aciltransferasas/química , Secuencia de Aminoácidos , Apoptosis/genética , Secuencia de Bases , Mapeo Cromosómico , Cromosomas Humanos Par 9/genética , Cartilla de ADN/genética , Exones , Glucosilceramidas/biosíntesis , Neuropatías Hereditarias Sensoriales y Autónomas/patología , Humanos , Datos de Secuencia Molecular , Subunidades de Proteína , Homología de Secuencia de Aminoácido , Serina C-PalmitoiltransferasaRESUMEN
BACKGROUND AND PURPOSE: Mutations in atlastin-1 (ATL-1), a gene known to cause pure, early-onset autosomal dominant hereditary spastic paraplegia SPG3A, have been recently reported to cause hereditary sensory neuropathy I (HSN I). We describe the detailed clinical and electrophysiologic findings in the first family with ulcero-mutilating sensory neuropathy carrying the c. C1065A, p.N355K mutation in ATL-1. METHODS: Detailed clinical and electrophysiologic studies were performed in affected and at-risk family members. Motor and sensory nerve conductions studies (NCS) were carried out in upper and lower limbs. ATL-1 was screened for mutations by direct sequencing. RESULTS: Ten patients were found to carry the N355K mutation. With the exception of the two youngest patients, all had trophic skin changes in the feet consisting mainly of painless ulcers. Frequently, amputation of toes, feet, or even more proximal parts of the lower legs became necessary. A variable degree of increased muscle tone was observed in younger patients, whilst some older affected individuals only presented with hyperreflexia of patellar tendon reflexes. NCS revealed signs of an axonal motor and sensory neuropathies. CONCLUSIONS: Our family carrying the N355K ATL1 mutation, which was initially diagnosed as HSN I, enlarges the SPG3A phenotype. We therefore suggest that patients with HSN I excluded for more common causes of HSN I, and in particular, affected individuals who exhibit additional pyramidal tract features should also be screened for mutations in ATL1.
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Proteínas de Unión al GTP/genética , Neuropatías Hereditarias Sensoriales y Autónomas/genética , Neuropatías Hereditarias Sensoriales y Autónomas/fisiopatología , Proteínas de la Membrana/genética , Mutación/genética , Tractos Piramidales/fisiopatología , Adolescente , Adulto , Anciano , Sustitución de Aminoácidos/genética , Femenino , Estudios de Asociación Genética/métodos , Neuropatías Hereditarias Sensoriales y Autónomas/diagnóstico , Humanos , Lactante , Masculino , Conducción Nerviosa/fisiología , Linaje , Adulto JovenRESUMEN
Additional neurological features have recently been described in seven families transmitting pathogenic mutations in OPA1, the most common cause of autosomal dominant optic atrophy. However, the frequency of these syndromal 'dominant optic atrophy plus' variants and the extent of neurological involvement have not been established. In this large multi-centre study of 104 patients from 45 independent families, including 60 new cases, we show that extra-ocular neurological complications are common in OPA1 disease, and affect up to 20% of all mutational carriers. Bilateral sensorineural deafness beginning in late childhood and early adulthood was a prominent manifestation, followed by a combination of ataxia, myopathy, peripheral neuropathy and progressive external ophthalmoplegia from the third decade of life onwards. We also identified novel clinical presentations with spastic paraparesis mimicking hereditary spastic paraplegia, and a multiple sclerosis-like illness. In contrast to initial reports, multi-system neurological disease was associated with all mutational subtypes, although there was an increased risk with missense mutations [odds ratio = 3.06, 95% confidence interval = 1.44-6.49; P = 0.0027], and mutations located within the guanosine triphosphate-ase region (odds ratio = 2.29, 95% confidence interval = 1.08-4.82; P = 0.0271). Histochemical and molecular characterization of skeletal muscle biopsies revealed the presence of cytochrome c oxidase-deficient fibres and multiple mitochondrial DNA deletions in the majority of patients harbouring OPA1 mutations, even in those with isolated optic nerve involvement. However, the cytochrome c oxidase-deficient load was over four times higher in the dominant optic atrophy + group compared to the pure optic neuropathy group, implicating a causal role for these secondary mitochondrial DNA defects in disease pathophysiology. Individuals with dominant optic atrophy plus phenotypes also had significantly worse visual outcomes, and careful surveillance is therefore mandatory to optimize the detection and management of neurological disability in a group of patients who already have significant visual impairment.
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Enfermedades del Sistema Nervioso Central/complicaciones , GTP Fosfohidrolasas/genética , Atrofia Óptica Autosómica Dominante/complicaciones , Adolescente , Adulto , Anciano , Enfermedades del Sistema Nervioso Central/genética , Enfermedades del Sistema Nervioso Central/metabolismo , Enfermedades del Sistema Nervioso Central/patología , Niño , Estudios de Cohortes , ADN Mitocondrial/análisis , ADN Mitocondrial/genética , Familia , Femenino , Heterocigoto , Humanos , Masculino , Persona de Mediana Edad , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Mutación , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/metabolismo , Atrofia Óptica Autosómica Dominante/patología , Fenotipo , Adulto JovenRESUMEN
BACKGROUND: SPG10 is an autosomal dominant form of hereditary spastic paraplegia (HSP), which is caused by mutations in the neural kinesin heavy chain KIF5A gene, the neuronal motor of fast anterograde axonal transport. Only four mutations have been identified to date. OBJECTIVE: To determine the frequency of SPG10 in European families with HSP and to specify the SPG10 phenotype. PATIENTS AND METHODS: 80 index patients from families with autosomal dominant HSP were investigated for SPG10 mutations by direct sequencing of the KIF5A motor domain. Additionally, the whole gene was sequenced in 20 of these families. RESULTS: Three novel KIF5A mutations were detected in German families, including one missense mutation (c.759G>T, p.K253N), one in frame deletion (c.768_770delCAA, p.N256del) and one splice site mutation (c.217G>A). Onset of gait disturbance varied from infancy to 30 years of age. All patients presented clinically with pure HSP, but a subclinical sensory-motor neuropathy was detected by neurophysiology studies. CONCLUSIONS: SPG10 accounts for approximately 3% of European autosomal dominant HSP families. All mutations affect the motor domain of kinesin and thus most likely impair axonal transport. Clinically, SPG10 is characterised by spastic paraplegia with mostly subclinical peripheral neuropathy.
Asunto(s)
Aberraciones Cromosómicas , Análisis Mutacional de ADN , Genes Dominantes/genética , Paraplejía Espástica Hereditaria/genética , Adulto , Edad de Inicio , Niño , Preescolar , Deleción Cromosómica , Europa (Continente) , Exones/genética , Femenino , Mutación del Sistema de Lectura , Trastornos Neurológicos de la Marcha/diagnóstico , Trastornos Neurológicos de la Marcha/genética , Genética de Población , Genotipo , Humanos , Cinesinas , Masculino , Persona de Mediana Edad , Mutación Missense , Examen Neurológico , Linaje , Fenotipo , Sitios de Empalme de ARN/genética , Análisis de Secuencia de ADN , Paraplejía Espástica Hereditaria/diagnósticoRESUMEN
Hereditary spastic paraplegia (HSP) is a heterogeneous condition characterised in its pure form by progressive lower limb spasticity. Mutations in SPG4 (encoding spastin) may be responsible for up to 40% of autosomal dominant (AD) cases. A cohort of 41 mostly pure HSP patients from Britain and Austria, 30 of whom displayed AD inheritance, was screened for mutations in SPG4 by single strand conformation polymorphism (SSCP) analysis followed by sequencing of samples with mobility shifts. We identified eight SPG4 mutations in pure AD HSP patients, seven of which were novel: one missense mutation within the AAA cassette (1633G>T), two splice site mutations (1130-1G>T, 1853+2T>A) and four frameshift mutations (190_208dup19, 1259_1260delGT, 1702_1705delGAAG, 1845delG). A novel duplication in intron 11 (1538+42_45dupTATA) was also detected. We report the HUGO-approved nomenclature of these mutations as well. Furthermore, we detected a silent change (1004G>A; P293P), previously reported as a mutation, which was also present in controls. The frequency of SPG4 mutations detected in pure AD HSP was 33.3%, suggesting that screening of such patients for SPG4 mutations is worthwhile. Most patients will have unique mutations. Screening of SPG4 in apparently isolated cases of HSP may be of less value.
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Adenosina Trifosfatasas/genética , Pruebas Genéticas/métodos , Mutación/genética , Paraplejía Espástica Hereditaria/genética , Exones/genética , Duplicación de Gen , Humanos , Intrones/genética , Leucocitos/química , EspastinaRESUMEN
OBJECTIVE: To elucidate genetic heterogeneity in ulcero-mutilating neuropathy. BACKGROUND: Ulcero-mutilating features and sensory loss have been observed in hereditary sensory neuropathy (HSN) and hereditary motor and sensory neuropathy (HMSN). HSN is characterized by marked distal sensory loss, frequent toe and foot ulcerations, osteomyelitis, and necrosis, which may be complicated by toe or limb amputations. Motor and autonomic nerve involvement can also occur to a variable degree. Recently, autosomal-dominant HSN type I was mapped to chromosome 9q22 in four families. In two other families with ulcero-mutilating neuropathy, a gene locus was assigned to chromosome 3q13-q22. Because motor symptoms were prominent in these latter two kinships, the disease was designated HMSN type IIB or Charcot-Marie-Tooth type 2B (CMT2B) neuropathy. METHODS: We report detailed clinical, electrophysiologic, and genetic data on a large Austrian family with ulcero-mutilating neuropathy, sensory loss, and amputations. RESULTS: Linkage analysis with chromosomal markers representing the HSN I and HMSN IIB loci excluded these gene loci in our family. CONCLUSIONS: These findings therefore indicate the existence of a third gene locus in autosomal-dominant inherited ulcero-mutilating neuropathies, showing that these neuropathies are genetically highly heterogeneous.
Asunto(s)
Enfermedades del Sistema Nervioso/genética , Úlcera Cutánea/genética , Adulto , Anciano , Anciano de 80 o más Años , Enfermedad de Charcot-Marie-Tooth/clasificación , Enfermedad de Charcot-Marie-Tooth/diagnóstico , Enfermedad de Charcot-Marie-Tooth/genética , Diagnóstico Diferencial , Femenino , Ligamiento Genético , Neuropatías Hereditarias Sensoriales y Autónomas/diagnóstico , Neuropatías Hereditarias Sensoriales y Autónomas/genética , Humanos , Masculino , Persona de Mediana Edad , Enfermedades del Sistema Nervioso/diagnóstico , Linaje , Úlcera Cutánea/diagnóstico , Úlcera Cutánea/patología , Síndrome , Dedos del PieRESUMEN
OBJECTIVE: To perform genotype-phenotype correlation and genetic linkage analysis in a family with axonal Charcot-Marie-Tooth (CMT) syndrome and ulcero-mutilating features. BACKGROUND: CMT2B is a rare disorder belonging to the group of axonal CMT syndromes that is clinically characterized by marked distal muscle weakness and wasting as well as a high frequency of foot ulcers, infections, and amputations. So far only two families with this disorder have been described in which molecular genetic studies have shown evidence of autosomal dominant inheritance with linkage to chromosome 3q13-q22. METHODS: The authors report a large Austrian family presenting with the typical clinical features of CMT2B. Detailed clinical and electrophysiologic data were obtained in 15 at-risk individuals and DNA samples from 19 family members were collected for genetic linkage studies. RESULTS: Eight family members were definitely affected upon clinical and electrophysiologic examination and the majority revealed pronounced distal muscle wasting and weakness as well as prominent sensory abnormalities, which were frequently complicated by infections and amputations. Electrophysiologic studies showed normal or slightly to moderately slowed motor nerve conduction velocities, markedly reduced compound motor action potential amplitudes with chronodispersion, and absent or reduced amplitudes of sensory nerve action potentials. The molecular genetic study demonstrates linkage to chromosome 3q13-q22. Haplotype analysis in affected individuals indicates that the CMT2B locus is located between the flanking markers D3S1589 and D3S1549, representing a region of 10 cM. CONCLUSIONS: This family is the third CMT2B family reported so far and confirms the existence of the CMT2B locus on chromosome 3q13-q22, which is responsible for a clinically and electrophysiologically homogeneous disorder with prominent distal muscle weakness and wasting, and ulcero-mutilating features. Marked sensory disturbances and the high frequency of foot ulcers, infections, and amputations in our patients seem to be typical for CMT2B. Recombination events in affected individuals reduce the CMT2B candidate gene interval considerably from 25 to 10 cM.
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Enfermedad de Charcot-Marie-Tooth/genética , Enfermedad de Charcot-Marie-Tooth/fisiopatología , Cromosomas Humanos Par 3/genética , Ligamiento Genético/genética , Genotipo , Humanos , Conducción Nerviosa/genética , Conducción Nerviosa/fisiología , Fenotipo , Secuencias Repetidas en TándemRESUMEN
OBJECTIVE: To study the long-term effects of vaginal dissection on the innervation of the striated urethral sphincter. METHODS: Perineal nerve terminal motor latency was measured before and 8 weeks and 1 year after anterior colporrhaphy, colpoperineoplasty, and vaginal hysterectomy in 33 women, 19 of whom also underwent endoscopic suspension of the bladder neck. RESULTS: In the entire series, the mean perineal nerve terminal motor latency was prolonged before surgery over that in normal continent women and further prolonged 8 weeks and 1 year postoperatively. In the subjects who underwent vaginal hysterectomy and anterior colporrhaphy, perineal motor latencies were not significantly prolonged at the 8-week postoperative follow-up and had almost returned to preoperative values 1 year later. However, in those who underwent additional endoscopic bladder neck suspension, perineal motor latencies were prolonged at both postoperative follow-up examinations. Perineal motor latencies were unchanged 1 year postoperatively in continent patients (N = 19) but were prolonged in incontinent patients (N = 14). CONCLUSION: Vaginal dissection, especially during endoscopic bladder neck suspension, can worsen preexisting perineal neuropathy in patients with pelvic relaxation and stress incontinence.
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Músculo Esquelético/inervación , Complicaciones Posoperatorias , Uretra/inervación , Vagina/cirugía , Adulto , Anciano , Femenino , Humanos , Persona de Mediana Edad , Músculo Esquelético/fisiopatología , Diafragma Pélvico/inervación , Diafragma Pélvico/fisiopatología , Complicaciones Posoperatorias/fisiopatología , Tiempo de Reacción , Factores de Tiempo , Uretra/fisiopatología , Incontinencia Urinaria de Esfuerzo/cirugíaRESUMEN
The second lumbrical-interosseus distal motor latency (2LI-DML) was compared prospectively in 450 hands. Median nerve function was assessed by standard motor and sensory electrophysiological tests. In a control group of 100 hands the upper limit of normal for the 2LI-DML was 0.5 ms. In all hands studied the correlation coefficients of 2LI-DML were higher with sensory nerve tests than with motor studies. Carpal tunnel syndrome (CTS) was diagnosed clinically in 276 hands, and 174 showed no clinical signs of CTS. The 2LI-DML was prolonged in 269 of the 276 hands, with clinical signs of CTS and normal in 170 of 174 non-CTS hands. Thus the 2LI-DML resulted in a sensitivity of 97.5%. On the other hand, combining the standard tests yielded a sensitivity of 98.5 %. In 31 of 36 additional hands a lumbrical response was recorded, although motor and sensory responses form standard median nerve conduction studies were absent, and the 2LI-DML was substantially prolonged. The 2LI-DML therefore represents a highly sensitive, fast, easy-to-perform, and cost-efficient method to study median nerve function across the wrist and may help to localize the lesion in cases in which standard electrophysiological methods fail.
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Síndrome del Túnel Carpiano/fisiopatología , Potenciales Evocados Motores , Potenciales Evocados Somatosensoriales , Nervio Mediano/fisiología , Conducción Nerviosa , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Síndrome del Túnel Carpiano/diagnóstico , Diagnóstico Diferencial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Sensibilidad y EspecificidadRESUMEN
Hereditary spastic paraplegia is a group of clinically and genetically heterogeneous disorders consisting of pure and complicated forms. A variant with the additional features of severe atrophy of the small hand muscles, dysarthria, mental retardation, and short stature has been termed Troyer syndrome (MIM#275900) after the name of Old Order Amish families suffering from these symptoms. We report here an Austrian family with two individuals who exhibit all the features of Troyer syndrome, and provide additional data on this disorder. Electrophysiological studies showed chronic denervation and reduced motor nerve conduction velocities but normal sensory potentials. Muscle biopsy revealed a neurogenic pattern while the sural nerve was normal on histological examination. Brain abnormalities on magnetic resonance imaging consisted of a thin corpus callosum with a poorly developed cingulate gyrus and mild periventricular signal hyperintensities. These findings characterize the Troyer syndrome as a disorder of the first and second motor neuron with additional damage in the brain. The morphological features observed in this family may contribute to the grouping and subsequent understanding of complicated forms of hereditary spastic paraplegia, together with similar observations in other, more recently reported families.
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Agenesia del Cuerpo Calloso , Enfermedad de la Neurona Motora/genética , Músculo Esquelético/patología , Paraplejía Espástica Hereditaria/genética , Adulto , Biopsia , Cuerpo Calloso/patología , Femenino , Mano , Humanos , Imagen por Resonancia Magnética , Enfermedad de la Neurona Motora/fisiopatología , Conducción Nerviosa , Linaje , Paraplejía Espástica Hereditaria/fisiopatología , SíndromeRESUMEN
The Roussy-Lévy syndrome (MIM #180800) was described in 1926 as a disorder presenting with pes cavus and tendon areflexia, distal limb weakness, tremor in the upper limbs, gait ataxia and distal sensory loss. We report a family with affected members in four generations, showing these clinical signs of Roussy-Lévy syndrome and a partial duplication at chromosome 17p11.2. This genetic defect is commonly found in patients with the hypertrophic form of the Charcot-Marie-Tooth syndrome. Our finding provides evidence against the Roussy-Lévy syndrome as a distinct entity but suggests a close relation with the Charcot-Marie-Tooth syndrome. What causes the additional features of gait ataxia and essential tremor needs further clarification.
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Enfermedad de Charcot-Marie-Tooth/genética , Cromosomas Humanos Par 17/genética , Familia de Multigenes , Potenciales de Acción , Enfermedad de Charcot-Marie-Tooth/patología , Enfermedad de Charcot-Marie-Tooth/fisiopatología , Electromiografía , Femenino , Pie/patología , Mano/patología , Humanos , Masculino , Conducción Nerviosa , Examen Neurológico , Linaje , FenotipoRESUMEN
OBJECTIVE: Ganglioside-induced differentiation associated-protein 1 (GDAP1) mutations are commonly associated with autosomal recessive Charcot-Marie-Tooth (ARCMT) neuropathy; however, in rare instances, they also lead to autosomal dominant Charcot-Marie-Tooth (ADCMT). We aimed to investigate the frequency of disease-causing heterozygous GDAP1 mutations in ADCMT and their associated phenotype. METHODS: We performed mutation analysis in a large cohort of ADCMT patients by means of bidirectional sequencing of coding regions and exon-intron boundaries of GDAP1. Intragenic GDAP1 deletions were excluded using an allele quantification assay. We confirmed the pathogenic character of one sequence variant by in vitro experiments assaying mitochondrial morphology and function. RESULTS: In 8 Charcot-Marie-Tooth disease (CMT) families we identified 4 pathogenic heterozygous GDAP1 mutations, 3 of which are novel. Three of the mutations displayed reduced disease penetrance. Disease onset in the affected individuals was variable, ranging from early childhood to adulthood. Disease progression was slow in most patients and overall severity milder than typically seen in autosomal recessive GDAP1 mutations. Electrophysiologic changes are heterogeneous but compatible with axonal neuropathy in the majority of patients. CONCLUSIONS: With this study, we broaden the phenotypic and genetic spectrum of autosomal dominant GDAP1-associated neuropathies. We show that patients with dominant GDAP1 mutations may display clear axonal CMT, but may also have only minimal clinical and electrophysiologic abnormalities. We demonstrate that cell-based functional assays can be reliably used to test the pathogenicity of unknown variants. We discuss the implications of phenotypic variability and the reduced penetrance of autosomal dominant GDAP1 mutations for CMT diagnostic testing and counseling.
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Enfermedad de Charcot-Marie-Tooth/genética , Proteínas del Tejido Nervioso/genética , Animales , Axones/patología , Células COS , Chlorocebus aethiops , Estudios de Cohortes , Análisis Mutacional de ADN , Exones/genética , Genes Dominantes , Haplotipos , Células HeLa , Humanos , Intrones/genética , Mitocondrias/metabolismo , Mitocondrias/patología , Mutación , Paternidad , Linaje , Fenotipo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
OBJECTIVE: Hereditary spastic paraplegias (HSPs) are very heterogeneous inherited neurodegenerative disorders. Our group recently identified ZFYVE26 as the gene responsible for one of the clinical and genetic entities, SPG15. Our aim was to describe its clinical and mutational spectra. METHODS: We analyzed all exons of SPG15/ZFYVE26 gene by direct sequencing in a series of 60 non-SPG11 HSP subjects with associated mental or MRI abnormalities, including 30 isolated cases. The clinical data were collected through the SPATAX network. RESULTS: We identified 13 novel truncating mutations in ZFYVE26, 12 of which segregated at the homozygous or compound heterozygous states in 8 new SPG15 families while 1 was found at the heterozygous state in a single family. Two of 3 splice site mutations were validated on mRNA of 2 patients. The SPG15 phenotype in 11 affected individuals was characterized by early onset HSP, severe progression of the disease, and mental impairment dominated by cognitive decline. Thin corpus callosum and white matter hyperintensities were MRI hallmarks of the disease in this series. CONCLUSIONS: The mutations are truncating, private, and distributed along the entire coding sequence of ZFYVE26, which complicates the analysis of this gene in clinical practice. In our series of patients with hereditary spastic paraplegia-thin corpus callosum, the largest analyzed so far, SPG15 was the second most frequent form (11.5%) after SPG11. Both forms share similar clinical and imaging presentations with very few distinctions, which are, however, insufficient to infer the molecular diagnosis when faced with a single patient.
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Proteínas Portadoras/genética , Cuerpo Calloso/patología , Mutación , Paraplejía Espástica Hereditaria/genética , Paraplejía Espástica Hereditaria/patología , Adolescente , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Niño , Cuerpo Calloso/diagnóstico por imagen , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Tomografía de Emisión de Positrones/métodos , Índice de Severidad de la Enfermedad , Paraplejía Espástica Hereditaria/diagnóstico por imagen , Tomografía Computarizada de Emisión de Fotón Único/métodosRESUMEN
Autosomal recessive Charcot-Marie-Tooth syndrome (AR-CMT) is often characterised by an infantile disease onset and a severe phenotype. Mutations in the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene are thought to be a common cause of AR-CMT. Mutations in the periaxin (PRX) gene are rare. They are associated with severe demyelination of the peripheral nerves and sometimes lead to prominent sensory disturbances. To evaluate the frequency of GDAP1 and PRX mutations in early onset CMT, we examined seven AR-CMT families and 12 sporadic CMT patients, all presenting with progressive distal muscle weakness and wasting. In one family also prominent sensory abnormalities and sensory ataxia were apparent from early childhood. In three families we detected four GDAP1 mutations (L58LfsX4, R191X, L239F and P153L), one of which is novel and is predicted to cause a loss of protein function. In one additional family with prominent sensory abnormalities a novel homozygous PRX mutation was found (A700PfsX17). No mutations were identified in 12 sporadic cases. This study suggests that mutations in the GDAP1 gene are a common cause of early-onset AR-CMT. In patients with early-onset demyelinating AR-CMT and severe sensory loss PRX is one of the genes to be tested.
Asunto(s)
Enfermedad de Charcot-Marie-Tooth/genética , Proteínas de la Membrana/genética , Mutación , Proteínas del Tejido Nervioso/genética , Edad de Inicio , Ataxia/patología , Enfermedad de Charcot-Marie-Tooth/epidemiología , Enfermedad de Charcot-Marie-Tooth/patología , Niño , Preescolar , Enfermedades Desmielinizantes/patología , Salud de la Familia , Femenino , Homocigoto , Humanos , Lactante , Recién Nacido , Masculino , Debilidad Muscular/patología , Nervios Periféricos/patología , Trastornos de la Sensación/patología , SíndromeRESUMEN
BACKGROUND: Hereditary spastic paraplegia (HSP) is a genetically heterogeneous neurodegenerative disease. The most frequent cause of autosomal dominant HSP is mutation of SPAST (SPG4 locus), but additional pedigrees remain mutation negative by conventional screening despite linkage to SPG4. OBJECTIVE: To determine the frequency of genomic copy number aberrations of SPAST in autosomal dominant HSP. METHODS: We developed and validated a multiplex ligation-dependent probe amplification assay targeting SPAST and SPG3A, another gene frequently involved in autosomal dominant HSP. In a multicenter study we subsequently investigated 65 index patients with autosomal dominant HSP, all of whom had previously been screened negative for SPAST mutations. Independent secondary samples, additional family members, and cDNA were analyzed to confirm positive findings. RESULTS: Aberrant MLPA profiles were identified in 12 cases (18%). They exclusively affect SPAST, represent deletions, segregate with the disease, and are largely pedigree specific. Internal SPAST deletions entail expression of correspondingly shortened transcripts, which vary in stability. Age at onset in SPAST deletion carriers does not differ from that associated with other SPAST mutations. CONCLUSIONS: Partial SPAST deletions, but not SPAST amplifications and SPG3A copy number aberrations, represent an underestimated cause of autosomal dominant hereditary spastic paraplegia. Partial SPAST deletions are likely to act via haploinsufficiency.
Asunto(s)
Adenosina Trifosfatasas/genética , Eliminación de Gen , Frecuencia de los Genes/genética , Paraplejía Espástica Hereditaria/genética , Adolescente , Adulto , Niño , Dosificación de Gen/genética , Haploidia , Humanos , Persona de Mediana Edad , Linaje , EspastinaRESUMEN
Hereditary sensory and autonomic neuropathy type II (HSAN-II) is caused by recessive mutations in the HSN2 gene assigned to chromosome 12p13.33. The authors report three unrelated HSAN-II families with homozygous or compound heterozygous mutations resulting in the truncation of the HSN2 protein. Genotype-phenotype correlations indicated that HSN2 mutations are associated with an early childhood onset of a predominantly sensory neuropathy, complicated by acromutilations in both upper and lower limbs.