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PubMed1979

Charcot-Marie-Tooth disease associated with retinal pigment dystrophy and protanopia. Neurological, ophthalmological and genetic study of a family.

Neurological, ophthalmological and genetic investigations were performed on a family, a member of which presented with a rare association of tapeto-retinal degeneration, protanopia and Charcot-Marie-Tooth disease (CMT), and asked for genetic counseling. The neurological enquiry was completed by measurement of motor nerve conduction velocity in several completed by measurement of motor nerve conduction velocity in several members of the family. The propositus was submitted to a muscle biopsy. The ophthalmological examination included ophthalmoscopy, fluorescein angiography, electroretinogram and electrooculogram. The propositus, a woman aged 40, had typical CMT disease and her father also had a mild form of it. She had protanopia as had her father, her son and her nephew. In addition she had large macular pigmented changes, described as retinal dystrophy, "flavus flavimaculatus." Her mother had only senile pigmented modification of the fundus and her three daughters had mild macular pigmented changes, like "salt and pepper." Two genes are probably involved: one for protanopia with X linked recessive inheritance, the other responsible of CMT and tapeto-retinal degeneration, with an autosomal dominant inheritance, giving a 50% risk of recurrence.

Adolescent↗
PubMed1996

Severe vincristine neuropathy in Charcot-Marie-Tooth disease type 1A.

BACKGROUND: A general predisposition for vincristine-related neuropathy has been observed in persons with a family history of hereditary neuropathies. METHODS: In a retrospective case series, we investigated the possible association between the DNA rearrangement found in patients with Charcot-Marie-Tooth Disease Type 1A (CMT1A) and susceptibility to the neurotoxicity of vincristine. In selected patients and family members, we performed electrodiagnostic studies and analyzed DNA samples for 17p11.1-12 duplication associated with CMT1A. RESULTS: We describe three families with autosomal dominant CMT1, among whom a family member with a neoplastic disease suffered rapid onset, severe neuropathy after receiving initial doses of vincristine as a part of a routine chemotherapy protocol. All three families had at least one affected family member with 17p11.2-12 duplication. CONCLUSIONS: These cases show that 17p11.2-12 duplication predisposes patients to severe neurotoxicity from vincristine and that this drug should be avoided with patients with CMT1A. It is therefore essential to obtain a detailed family history for all oncology patients to screen for possible hereditary neuropathies. In patients with unexplained or preexisting familial neuropathy, testing for 17p11.2-12 duplication should be carried out prior to initiating vincristine therapy. Patients with other hereditary neuropathies may also be at risk for severe neurotoxic reactions.

Adolescent↗
PubMed1994

Hypertrophic motor and sensory neuropathy type I (Charcot-Marie-Tooth disease): ultrastructural study of sural nerve biopsy in members of a family.

Three members of a family with a hereditary neuropathy were studied. Light, electron microscopy and teasing of isolated fibres were performed. The findings confirmed the clinical and electrophysiological hypothesis of hypertrophic form of Charcot-Marie-Tooth disease. Hypertrophy of Schwann cells with the formation of onion bulb figures as the most evident ultrastructural feature, besides demyelination, remyelination and mild axonal degeneration. Recent data about the genetic transmission and pathogenesis of the hereditary motor and sensory neuropathies (HMSN) are discussed.

Adult↗
PubMed2000

Unequal exchange at the Charcot-Marie-Tooth disease type 1A recombination hot-spot is not elevated above the genome average rate.

An increasing number of human diseases and syndromes are being found to result from micro-duplications or microdeletions arising from meiotic recombination between homologous repeats on the same chromosome. The first microduplication syndrome delineated, Charcot-Marie-Tooth disease type 1A (CMT1A), results from unequal crossing over between two >98% identical 24 kb repeats (CMT1A-REPs) on chromosome 17. In addition to its medical significance, the CMT1A region has features that make it a unique resource for detailed analysis of human unequal recombination. Previous studies of CMT1A patients showed that the majority of unequal crossovers occurred within a small region (<1 kb) of the REPs suggesting the presence of a recombination hot-spot. We directly measured the frequency of unequal recombination in the hot-spot region using sperm from four normal individuals. Surprisingly, unequal recombination between the REPs occurs at a rate no greater than the average rate for the male genome (approximately 1 cM/Mb) and is the same as that expected for equally aligned REPs. This conclusion extends to humans the findings in yeast that recombination between repeated sequences far apart on the same chromosome may occur at similar frequencies to allelic recombination. Finally, the CMT1A hot-spot stands in sharp contrast to the human MS32 mini-satellite-associated hot-spot that exhibits highly enhanced recombination initiation in addition to positional specificity. One possibility is that the CMT1A hot-spot may consist of a region with genome average recombination potential embedded within a recombination cold-spot.

Adult↗
PubMed2006

Early clinical and electrophysiologic features of the two most common autosomal recessive forms of Charcot-Marie-Tooth disease in the Roma (Gypsies).

Our recent studies of the genetic epidemiology of neuromuscular disorders in Gypsies in Bulgaria have revealed that two private disorders, hereditary motor and sensory neuropathy type Lom and hereditary motor and sensory neuropathy type Russe, account for most cases of Charcot-Marie-Tooth disease in this population. In this study, we examined the clinical and electrophysiologic manifestations of the two disorders in childhood, aiming to identify the distinctive features that allow early differential diagnosis. The study included 13 patients, aged between 2 and 15 years. The childhood clinical manifestations of both neuropathies were similar, although they tended to be more severe in hereditary motor and sensory neuropathy type Lom. The nerve conduction velocities in hereditary motor and sensory neuropathy type Lom were lower than in hereditary motor and sensory neuropathy type Russe. Brainstem auditory evoked potentials were abnormal in hereditary motor and sensory neuropathy type Lom, even at an early age, and normal in hereditary motor and sensory neuropathy type Russe. Although electrophysiologic data provide a more reliable differentiation than clinical data, the definitive diagnosis should rely on genetic testing. (J Child Neurol 2006;21:20-25).

Adolescent↗
PubMed1996

Accumulation of peripheral myelin protein 22 in onion bulbs and Schwann cells of biopsied nerves from patients with Charcot-Marie-Tooth disease type 1A.

Peripheral myelin protein 22 (PMP-22) is a glycoprotein expressed in the myelin sheath of myelinated Schwann cells. Duplication of the PMP-22 gene and its gene dosage effect have been postulated to be involved in the pathogenesis in the majority of individuals with Charcot-Marie-Tooth disease type 1A (CMT1A). Northern blot analysis has demonstrated that the mean relative ratio of PMP-22 mRNA/beta-actin mRNA in biopsied nerves of patients with CMT1A is significantly higher than that in disease controls. To investigate whether the elevated expression of PMP-22 mRNA is reflected in the amount and the localization of PMP-22, we analyzed PMP-22, myelin basic protein (MBP), protein zero (P0), and S-100 immunoreactivities in biopsied nerves from six patients with CMT1A, five patients with other types of CMT, five patients with acquired demyelinating neuropathies, and two normal subjects. In all patients with CMT other than CMT1A and acquired demyelinating neuropathy, as well as in normal subjects, the myelin sheath was immunoreactive for PMP-22, MBP, and P0, while the Schwann cell cytoplasm was immunoreactive only for S-100. In five out of six patients with CMT1A, however, the PMP-22 immunoreactivity was present not only on the myelin sheath but also in the Schwann cell cytoplasm and onion bulbs (OBs). Although OBs are nonspecific and also seen in other inherited or acquired demyelinating neuropathies, the PMP-22-positive OBs were seen exclusively in CMT1A. The finding suggested that the expression of PMP-22 was abnormal for its localization and probably for the amount in patients with CMT1A carrying duplication of the PMP-22 gene.

Adolescent↗
PubMed1998

Autosomal dominant distal spinal muscular atrophy type V (dSMA-V) and Charcot-Marie-Tooth disease type 2D (CMT2D) segregate within a single large kindred and map to a refined region on chromosome 7p15.

Two separate disorders, autosomal dominant distal spinal muscular atrophy type V (dSMA-V) characterized by marked bilateral weakness in the hands and atrophy of thenar eminence and the first interosseous muscle, and Charcot-Marie-Tooth disease type 2D (CMT2D) characterized by sensory deficits in addition to the upper limb weakness and wasting, have been independently linked to chromosome 7p. We identified a multigenerational Mongolian kindred with 17 members affected with either dSMA-V or CMT2D and mapped both syndromes to the same region on chromosome 7p15. A maximum two-point lod score of 4.74 at recombination fraction zero was obtained with marker D7S474. Tight linkage without recombination was also detected with markers D7S526 and D7S632. A multipoint lod score of 6.07 suggested that the gene is located between markers D7S526 and D7S474. A single conserved haplotype was associated with dSMA-V and CMT2D. Based on informative recombination events, the disease locus was placed between markers D7S516 and D7S1514 within the 7p15 band. Data obtained from this study suggest that a single gene is responsible for both syndromes, dSMA-V and CMT2D, and extend our knowledge of the candidate region.

Adult↗
PubMed2004

[Different phenotypes of Charcot-Marie-Tooth disease caused by mutations in the same gene. Are classical criteria for classification still valid?].

Molecular genetic research is leading to the continuous discovery of new genes and protein involved in peripheral nerves function. Simultaneously, extended clinical, neurophysiological and pathological research has yielded new genotype-phenotype correlation on Charcot-Marie-Tooth disease (CMT). This has made it possible to know that several genes can cause both demyelinating (CMT1) and axonal (CMT2) phenotypes. Those observations have questioned the validity of some current criteria for CMT classification and raise the need for new strategies for diagnosis. The discovery of Schwann cell-axon interaction is a challenge for coming years. In this review, we extensively analyzed mutations of genes that give rise to CMT1 or CMT2 phenotypes. There are at least three forms of genetic variability. MPZ gene mutations yield a real allelism, that is, CMT1 or CMT phenotypes associated to specific mutation by site or quality. GADP1 and probably NF-L gene manifest different phenotypes but only in terms of nerve conduction velocity (CV). Evidence is provided that indicates that CV reduction in GADP-1 neuropathy may be the result of axonal loss. Finally a third form of variability is present in CMTX due to the degree of clinical expression in females related with the inactivation of chromosome X.

Adaptor Proteins, Signal Transducing↗
PubMed1987

Regional chromosomal assignment of human renin gene to 1q12----qter and use in linkage studies in Charcot-Marie-Tooth disease.

The gene for renin, previously mapped to human chromosome 1, was further localized to 1q12----qter using human-mouse somatic cell hybrid DNAs. The renin DNA probe used (lambda HR5) could detect a HindIII restriction fragment length polymorphism. When used in studies of 12 informative families, no linkage could be found between the renin gene and Charcot-Marie-Tooth disease. Furthermore, an association of any renin allele with hypertension was not apparent.

Animals↗
PubMed2005

Familial periodic paralysis and Charcot-Marie-Tooth disease in a 7-generation family.

BACKGROUND: A family with a complicated constellation of neurologic findings, including neuropathy, myotonia, and periodic paralysis, has been described in 4 studies in the medical literature since 1934. The underlying cause of their disease has been the subject of considerable speculation and has never been identified until now. OBJECTIVE: To identify the molecular basis of this family's neurologic disease. DESIGN: The coding regions of 6 genes that cause peripheral neuropathy and regions of the muscle sodium channel gene (SCN4A) were sequenced. RESULTS: A novel missense mutation (Arg67Pro) in the myelin protein zero gene was identified in 2 patients with Charcot-Marie-Tooth disease, and a common missense mutation (Thr704Met) was identified in the SCN4A gene in 4 family members. We discuss the difficulties of genotype-phenotype correlation in this family. CONCLUSIONS: These findings indicate that 2 independent mutations segregating in this family are responsible for the puzzling clinical picture.

Adolescent↗
PubMed2003

Rapid detection of duplication/deletion of the PMP22 gene in patients with Charcot-Marie-Tooth disease Type 1A and hereditary neuropathy with liability to pressure palsy by real-time quantitative PCR using SYBR Green I dye.

Mutations and altered gene dosage of the peripheral myelin protein (PMP22) gene in chromosome 17p11.2-12 are the main causes for hereditary neuropathies, accounting for approximately 70% of all cases. Patients with duplication of the PMP22 develop Charcot-Marie-Tooth disease type 1A (CMT1A) and deletion of one PMP22 allele leads to hereditary neuropathy with liability to pressure palsy (HNPP). Twenty patients with CMT1A, 17 patients with HNPP, and 18 normal family members and 28 normal controls were studied by real-time quantitative PCR using SYBR Green I on the ABI 7700 Sequence Detection System. The copy number of the PMP22 gene was determined by the comparative threshold cycle method and the albumin was used as a reference gene. The PMP22 duplication ratio ranged from 1.45 to 2.06 and the PMP22 deletion ratio ranged from 0.42 to 0.64. The PMP22 ratio in normal controls, including normal family members, ranged from 0.85 to 1.26. No overlap was found between patients with CMT1A or patients with HNPP and normal controls. This method is fast, highly sensitive, specific, and reproducible in detecting PMP22 duplication and deletion in CMT1A and HNPP patients, respectively.

Benzothiazoles↗
PubMed1989

Assessment and management of pes cavus in Charcot-Marie-tooth disease.

The sequential approach to evaluating the cavus foot is integrated with a description and assessment of the various treatment options. Decision making in the treatment of these cases is complicated by the progressive neurologic condition that underlies many of these deformities. An effort is made to recommend the most appropriate surgical intervention based on the nature of the deformity and its rigidity. Although these principles apply to all cavus feet, the deformity in Charcot-Marie-Tooth disease is the most difficult to treat and the most prone to recurrence because of the progressive nature of the muscular imbalance causing it.

Charcot-Marie-Tooth Disease↗
PubMed1990

Isolation and use of chromosome 1 probes for linkage studies on Charcot-Marie-Tooth disease.

Nine probes were isolated from a human chromosome 1 enriched library and mapped to regions of chromosome 1 using somatic cell hybrid lines. One clone, LR67, which mapped to 1q12----q23 detected a BglI RFLP. This probe, as well as 4 other known chromosome 1 markers, alpha-spectrin, Factor XIIIB, DR10 and DR78, were used for linkage studies in 15 Charcot-Marie-Tooth disease (CMT1) families. Close linkage of CMT1 to any of the 5 markers was not indicated. Total lod scores excluded linkage of CMT1 to LR67 and to DR10 at 5 cM or less, to DR78 at 10 cM or less, alpha-spectrin at 15 cM or less and Factor XIIIB at 20 cM or less. Possible linkage, however, was shown between LR67 and CMT1 at a distance of 30 cM. Also linkage at a distance of 5 cM was detected between this probe and alpha-spectrin.

Charcot-Marie-Tooth Disease↗
PubMed2007

Mutation scanning the GJB1 gene with high-resolution melting analysis: implications for mutation scanning of genes for Charcot-Marie-Tooth disease.

BACKGROUND: X-linked Charcot-Marie-Tooth type 1 disease has been associated with 280 mutations in the GJB1 [gap junction protein, beta 1, 32 kDa (connexin 32, Charcot-Marie-Tooth neuropathy, X-linked)] gene. High-resolution melting analysis with an automated instrument can be used to scan DNA for alterations, but its use in X-linked disorders has not been described. METHODS: A 96-well LightScanner for high resolution melting analysis was used to scan amplicons of the GJB1 gene. All mutations reported in this study had been confirmed previously by sequence analysis. DNA samples were amplified with the double-stranded DNA-binding dye LC Green Plus. Melting curves were analyzed as fluorescence difference plots. The shift and curve shapes of melting profiles were used to distinguish controls from patient samples. RESULTS: The method detected each of the 23 mutations used in this study. Eighteen known mutations provided validation of the high-resolution melting method and a further 5 mutations were identified in a blind study. Altered fluorescence difference curves for all the mutations were easily distinguished from the wild-type melting profile. CONCLUSION: High-resolution melting analysis is a simple, sensitive, and cost-efficient alternative method to scan for gene mutations in the GJB1 gene. The technology has the potential to reduce sequencing burden and would be suitable for mutation screening of exons of large multiexon genes that have been discovered to be associated with Charcot Marie Tooth neuropathy.

Charcot-Marie-Tooth Disease↗
PubMed1994

Charcot-Marie-Tooth disease: a new paradigm for the mechanism of inherited disease.

Recent work has identified the genes and mutational mechanisms that underlie several inherited diseases of the peripheral nervous system and has provided both the first genetic rationale for classification of these disorders and an insight into their biological basis. These studies have yielded some surprising findings, including the discovery that two very different mutational mechanisms (duplication and point mutation) can result in a similar clinical phenotype in Charcot-Marie-Tooth disease type 1A, and that mutations involving the same gene can give rise to different clinical phenotypes.

Amino Acid Sequence↗
PubMed1989

Class II antigen expression on human cultured Schwann cells from patients with Charcot-Marie-Tooth disease.

T lymphocytes control the extent of the immune reaction by recognizing the antigen in connection with class II histocompatibility surface molecules, coded by genes located on the HLA-D locus. The expression of HLA-DR antigens is confined to a few antigen presenting cells, like lymphocytes and macrophages, which can therefore induce the initial phase of the immune reaction. We report that also Schwann cells (SC) from patients with Charcot-Marie-Tooth disease (CMT), an hereditary disorder of the peripheral nervous system, are able to express HLA-DR antigens. Human SC cultures were carried out from sural nerve biopsies of CMT and normal control cases. Cultures were tested on day 7, 14, 21 and 28, with double immunofluorescence technique using rabbit antiserum anti-S-100 and mouse anti-HLA-DR monoclonal antibody. SC from CMT were HLA-DR positive since the first few days, continuing to express class II antigens for all the duration of the culture. The presence of class II antigens on cultured SC from CMT disease suggests that immune-mediated mechanisms may be relevant in the pathogenesis of this degenerative disorder of the peripheral nervous system.

Cells, Cultured↗
PubMed1998

Quadriceps strength and timed motor performances in myotonic dystrophy, Charcot-Marie-Tooth disease, and healthy subjects.

BACKGROUND AND PURPOSE: The leading hypothesis was that a relation exists between muscular strength and functional abilities. Therefore a study was undertaken to quantify such a relationship in a population of subjects with different muscular strengths. This population consisted of healthy subjects and subjects with slowly progressive neuromuscular disorders. METHODS: The study included 33 patients with myotonic dystrophy, 29 patients with Charcot-Marie-Tooth disease and 20 healthy subjects. Isokinetic and isometric knee torques were measured on an isokinetic dynamometer at various velocities. The following activities were timed: descending and ascending stairs, rising from a chair, rising from supine, walking at natural speed and walking at maximum speed. RESULTS: The population covered a wide range of the variables: whereas the healthy subjects performed best (i.e. had the highest knee torques and performed the activities most quickly), the myotonic dystrophy group included the subjects with the lowest knee torques. The natural logarithms (In) of isokinetic extension torque at the highest velocity (120 degrees/s) and those of the time taken to perform the described activities showed the highest levels of correlation. It was found that after correction for age and weight, 56% (walking at natural speed) to 73% (descending stairs) of the variance in the In of the time taken could be attributed to the variance in the In of the torques. CONCLUSION AND DISCUSSION: A strong relation between quadriceps strength and timed motor performances were demonstrated. The impact of strength reduction on time taken was most obvious in subjects with considerably decreased strength. Therefore, it is feasible to try to influence muscle strength in patients with relevant strength reduction in order to achieve better functional ability.

Adolescent↗
PubMed1989

[Carbamazepine-sensitive neuromyotonia and Charcot-Marie-Tooth disease of the neuronal type].

Following an anti-smallpox vaccination a 17 year-old boy developed spontaneous muscular activity with cramps and fasciculations in the lower limbs. There was distal amyotrophy of the lower limbs and pes cavus. Clinical signs suggested a cholinergic hyperfunction. EMG showed a significant spontaneous activity and was neurogenic in the lower limbs. Nerve conduction velocities were consistent with axonal damage. Muscular biopsy showed aspects of chronic denervation. Neuromyotonia disappeared with carbamazepine treatment. This case can be added to the reported associations of neuromyotonia and Charcot-Marie-Tooth disease. Such cases are an additional argument for the axonal origin of neuromyotonia.

Adolescent↗