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Ho CC, Tai SM, Lee ECN, Mak TSH, Liu TKT, Tang VWL, Poon WT. Rapid Identification of Pathogenic Variants in Two Cases of Charcot-Marie-Tooth Disease by Gene-Panel Sequencing. Int J Mol Sci 2017; 18:ijms18040770. [PMID: 28379183 PMCID: PMC5412354 DOI: 10.3390/ijms18040770] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 03/28/2017] [Accepted: 03/31/2017] [Indexed: 12/14/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is a common inherited peripheral neuropathy affecting up to 1 in 1214 of the general population with more than 60 nuclear genes implicated in its pathogenesis. Traditional molecular diagnostic pathways based on relative prevalence and clinical phenotyping are limited by long turnaround time, population-specific prevalence of causative variants and inability to assess multiple co-existing variants. In this study, a CMT gene panel comprising 27 genes was used to uncover the pathogenic mutations in two index patients. The first patient is a 15-year-old boy, born of consanguineous parents, who has had frequent trips and falls since infancy, and was later found to have inverted champagne bottle appearance of bilateral legs and foot drop. His elder sister is similarly affected. The second patient is a 37-year-old woman referred for pre-pregnancy genetic diagnosis. During early adulthood, she developed progressive lower limb weakness, difficulties in tip-toe walking and thinning of calf muscles. Both patients are clinically compatible with CMT, have undergone multiple genetic testings and have not previously received a definitive genetic diagnosis. Patients 1 and 2 were found to have pathogenic homozygous HSPB1:NM_001540:c.250G>A (p.G84R) variant and heterozygous GDAP1:NM_018972:c.358C>T (p.R120W) variant, respectively. Advantages and limitations of the current approach are discussed.
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Affiliation(s)
- Chi-Chun Ho
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China.
| | - Shuk-Mui Tai
- Department of Paediatrics & Adolescent Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China.
| | - Edmond Chi-Nam Lee
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China.
| | - Timothy Shin-Heng Mak
- Centre for Genomic Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China.
| | - Timothy Kam-Tim Liu
- Department of Paediatrics & Adolescent Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China.
| | - Victor Wai-Lun Tang
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China.
| | - Wing-Tat Poon
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China.
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HAHN ANGELIKAF, BOLTON CHARLESF, WHITE CHRISTOPHERM, BROWN WILLIAMF, TUUHA SASCHAE, TAN CHARLESC, AINSWORTH PETERJ. Genotype/Phenotype Correlations in X-Linked Dominant Charcot-Marie-Tooth Disease. Ann N Y Acad Sci 2006; 883:366-382. [DOI: 10.1111/j.1749-6632.1999.tb08598.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Kleopa KA, Scherer SS. Molecular genetics of X-linked Charcot-Marie-Tooth disease. Neuromolecular Med 2006; 8:107-22. [PMID: 16775370 DOI: 10.1385/nmm:8:1-2:107] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 11/10/2005] [Accepted: 11/17/2005] [Indexed: 11/11/2022]
Abstract
The X-linked form of Charcot-Marie-Tooth disease (CMT1X) is the second most common molecularly designated form of hereditary motor and sensory neuropathy. The clinical phenotype is characterized by progressive distal muscle atrophy and weakness, areflexia, and variable sensory abnormalities. Affected males have moderate-to-severe symptoms, whereas heterozygous females are usually mildly affected or even asymptomatic. Several patients also have manifestations of central nervous system involvement or hearing impairment. Electrophysiological and pathological studies of peripheral nerves show evidence of demyelinating neuropathy with prominent axonal degeneration. A large number of mutations in the GJB1 gene encoding the gap junction (GJ) protein connexin32 (Cx32) cause CMT1X. Cx32 is expressed by Schwann cells and oligodendrocytes, as well as by other tissues, and the GJ formed by Cx32 play an important role in the homeostasis of myelinated axons. The reported CMT1X mutations are diverse and affect both the promoter region as well as the coding region of GJB1. Many Cx32 mutants fail to form functional GJ, or form GJ with abnormal biophysical properties. Furthermore, Cx32 mutants are often retained intracellularly either in the endoplasmic reticulum or Golgi in which they could potentially have additional dominant-negative effects. Animal models of CMT1X demonstrate that loss of Cx32 in myelinating Schwann cells causes a demyelinating neuropathy. No definite phenotype-genotype correlation has yet been established for CMT1X and effective molecular based therapeutics for this disease, remain to be developed.
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Affiliation(s)
- Kleopas A Kleopa
- Department of Clinical Neurosciences, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.
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Valentijn LJ, Baas F. Genetic basis of peripheral neuropathies. PROGRESS IN BRAIN RESEARCH 1999; 117:249-64. [PMID: 9932413 DOI: 10.1016/s0079-6123(08)64020-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- L J Valentijn
- Department of Neurology, K2-214 Academic Medical Center, Amsterdam, The Netherlands
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Sartucci F, Sagliocco L, Murri L. Central motor pathway evaluation using magnetic coil stimulation in hereditary motor and sensory neuropathy type I (HMSN type I, Charcot-Marie-Tooth disease). Int J Neurosci 1997; 92:145-59. [PMID: 9522263 DOI: 10.3109/00207459708986398] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Central Motor Conduction Time (CMCT) was investigated in 18 patients (5 m, 13 f; age range: 11-69 yrs) with clinical and electrophysiological features of HMSN type I, using Magnetic Coil (MC) stimulation. No one exhibited clinically pyramidal signs. Brain stimulation Motor Evoked Potentials (MEPs), recorded monolaterally from the left abductor digiti minimi (ADM) and tibialis anterior (TA) muscles, were evoked in all patients from upper extremities and absent in 11.1% from lower limbs. Total Motor Conduction Time (TMCT), as well as Peripheral Motor Conduction Time estimated by either magnetic nerve root stimulation (mag-PMCT) or F-wave latency values (F-PMCT), were markedly delayed in all patients. Central Motor Conduction Time was calculated by subtracting both the latency of mag-PMCT (mag-CMCT) and F-PMCT (F-CMCT) from that one obtained by cortical stimulation. F-CMCT was abnormal in 22.2% in upper extremities and in 27.8% patients from lower extremities, whereas mag-CMCT in 22.2% from ADM muscles and in 33.3% from TA muscles. Furthermore, CMCT to both methods was not possible to evaluate in 5.6% from upper and lower extremities and following magnetic root stimulation in 11.1% from lower limbs. These findings prove lower motor neuron involvement, in agreement with electroneurographic data, and suggest a possible central motor pathways impairment, even in patients without any clinical evidence, but they cannot explain which is the underlying pathophysiological mechanism, a true upper motor neuron involvement or an abnormal spinal motor neuron excitability.
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Affiliation(s)
- F Sartucci
- Department of Neurosciences, University of Pisa, Italy.
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Ionasescu V, Ionasescu R, Searby C. Correlation between connexin 32 gene mutations and clinical phenotype in X-linked dominant Charcot-Marie-Tooth neuropathy. AMERICAN JOURNAL OF MEDICAL GENETICS 1996; 63:486-91. [PMID: 8737658 DOI: 10.1002/(sici)1096-8628(19960614)63:3<486::aid-ajmg14>3.0.co;2-i] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We studied the relationship between the genotype and clinical phenotype in 27 families with dominant X-linked Charcot-Marie-Tooth (CMTX1) neuropathy. Twenty-two families showed mutations in the coding region of the connexin32 (cx32) gene. The mutations include four nonsense mutations, eight missense mutations, two medium size deletions, and one insertion. Most missense mutations showed a mild clinical phenotype (five out of eight), whereas all nonsense mutations, the larger of the two deletions, and the insertion that produced frameshifts showed severe phenotypes. Five CMTX1 families with mild clinical phenotype showed no point mutations of the cx32 gene coding region. Three of these families showed positive genetic linkage with the markers of the Xq13.1 region. The genetic linkage of the remaining two families could not be evaluated because of their small size.
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Affiliation(s)
- V Ionasescu
- Department of Pediatrics, University of Iowa Hospitals and Clinics, Iowa City 52242, USA
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Guidetti D, Vescovini E, Motti L, Ghidoni E, Gemignani F, Marbini A, Patrosso MC, Ferlini A, Solime F. X-linked bulbar and spinal muscular atrophy, or Kennedy disease: clinical, neurophysiological, neuropathological, neuropsychological and molecular study of a large family. J Neurol Sci 1996; 135:140-8. [PMID: 8867070 DOI: 10.1016/0022-510x(95)00283-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We report the clinical, neurophysiological, neuropsychological, neuropathological and molecular findings in a large family with X-linked bulbar and spinal muscular atrophy (X-BSMA). Molecular study, performed in 28 family members, showed an increase in the number of CAG repeats in 6 affected males (including 2 presymptomatic patients), and in 10 females, of whom 5 were obligate carriers. All symptomatic patients showed, besides the typical manifestation of X-BSMA, neurophysiological signs of sensory nerve involvement, and abnormal findings in neuropsychological tests. Sural nerve biopsy, performed in two patients, was consistent with axonal atrophy and slow-rate degeneration, with secondary demyelination. Neurophysiological alterations were also present in 6 out of 8 carriers, consisting of neurogenic EMG changes in 3 cases and abnormal sensory action potentials (SAP) and reduced conduction velocity of the sural nerve in 3 cases. Abnormalities of at last two neuropsychological tests were found in 6 out of 8 carriers. Alterations of the sensory nerves in X-BSMA patients have been previously reported in some cases; however, we demonstrate for the first time sensory nerve involvement also in carriers. Evidence of central nervous system involvement, with neuropsychological impairment in all symptomatic patients and in some carriers, is another feature of this family, not previously reported in X-BSMA. In spite of the variable phenotypic features, the number of CAG repeats ranged from 40 to 44 in the affected patients, indicating that phenotypic expression was not related to the size of the mutation, but was probably age-related.
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Affiliation(s)
- D Guidetti
- Neurological Department, Santa Maria Nuova Hospital, Reggio Emilia, Italy
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Thomas FP, Lebo RV, Rosoklija G, Ding XS, Lovelace RE, Latov N, Hays AP. Tomaculous neuropathy in chromosome 1 Charcot-Marie-Tooth syndrome. Acta Neuropathol 1994; 87:91-7. [PMID: 7511317 DOI: 10.1007/bf00386259] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We performed morphological and immunohistochemical studies on sural nerve biopsies from two members of a Charcot-Marie-Tooth type 1B family, in which a mutation of the P0 gene on chromosome 1 had been found. Biopsies showed a tomaculous neuropathy with loss of myelinated fibers and frequent small onion bulbs. Immunofluorescence with antibodies to P0 showed this protein to be present in tomaculous and non-tomaculous areas of the myelin sheath. The severity of the myelin abnormalities suggests that in this family Charcot-Marie-Tooth disease may result from a generalized disturbance of Schwann cells as a result of an abnormal P0 protein.
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Affiliation(s)
- F P Thomas
- Department of Pathology (Division of Neuropathology), College of Physicians & Surgeons, Columbia University, New York, NY
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Gabreëls-Festen AA, Gabreëls FJ, Jennekens FG. Hereditary motor and sensory neuropathies. Present status of types I, II and III. Clin Neurol Neurosurg 1993; 95:93-107. [PMID: 8344020 DOI: 10.1016/0303-8467(93)90002-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Abstract
The neuronal forms of hereditary motor and sensory neuropathy (HMSN) are genetically heterogeneous with observed autosomal dominant, autosomal recessive and X-linked dominant inheritance. All three forms are characterized by degeneration of select populations of motor and sensory neurons with accompanying atrophy and degeneration of their axons. Large calibre myelinated fibres are predominantly affected and fibre degeneration and fibre loss progresses from distally to proximally. Attempts of regeneration are noted in all except the severe childhood form. The clinical picture is that of peroneal and distal leg muscle wasting and weakness, distal sensory loss and areflexia. Hand muscles may be severely affected in the autosomal recessive and X-linked dominant forms. Motor and sensory nerve conduction velocities are only moderately slowed and evoked maximum compound motor and sensory amplitudes are reduced according to the degree of fibre loss. The gene locus remains unknown in both the autosomal dominant and autosomal recessive types. For the X-linked dominant HMSN, the gene locus has been mapped closely by linkage analysis to DNA loci in the pericentromeric region of the X-chromosome.
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Affiliation(s)
- A F Hahn
- Department of Clinical Neurological Sciences, University of Western Ontario, London, Canada
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Solders G, Correale J, Zhi W, Höjeberg B, Link H, Olsson T. Increased systemic B- and T-lymphocyte responses in hereditary motor and sensory neuropathy (HMSN I). J Neurol Sci 1992; 113:62-9. [PMID: 1281871 DOI: 10.1016/0022-510x(92)90266-n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Immune mechanisms of possible importance for the development and maintenance of peripheral nerve myelin breakdown in HMSN I were analysed by measuring B- and T-cell activation in blood, bone marrow and cerebrospinal fluid. Patients with polyneuropathies of other etiologies served as one control group and patients with tension headache as another. Flow cytometry of blood and bone marrow mononuclear cells revealed that an increased number of CD3+, CD4+ and CD4- CD8- T-cells expressed a late stage activation marker (Ta1). Analysis of T-cells primed for myelin antigens, by studies of IFN-gamma secretion in response to antigen in vitro, showed that both HMSN I and other polyneuropathy patients had low (but significant) numbers of T-cells recognizing whole PNS-myelin. Increased numbers of IgG- and IgM-producing cells were found in blood and bone marrow in the HMSN I patients. Patients with both HMSN I and the other polyneuropathies had few cells in peripheral blood and in bone marrow producing antibodies binding to P2, MAG and MBP in a solid phase immunospot assay. Many cells in the cerebrospinal fluid produced antibodies against MAG. Thus, there was a strong general activation of B- and T-cells in HMSN I while the immunity directed toward peripheral nerve was only slightly elevated. It is an open question if this immune activation is related to the primary gene defect or a secondary event to the nerve damage. The pathogenetic importance of the immune response in maintaining the nerve damage in HMSN I is unclear.
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Affiliation(s)
- G Solders
- Department of Neurology, Huddinge University Hospital, Sweden
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Abstract
Genetic mapping of genes which predispose to psychiatric illness is discussed in relation to recent developments in molecular genetic technology. Among the psychiatric disorders, the mechanism by which genetic factors contribute to illness is poorly understood, and the classification of phenotype (ill-status) is extremely complicated. These uncertainties, together with other complicating factors, tend to undermine the effectiveness of genetic linkage analysis. Two very powerful new molecular strategies have the potential to improve the overall gene mapping effort. First, new applications of polymerase chain reaction (PCR) technology will allow laboratories to generate much more genetic data than has been previously possible. Some of the factors which confound psychiatric linkage analysis should be mitigated by the larger data sets that will be generated with this technology. Second, the cloning of large segments of human chromosomes into yeast artificial chromosomes (YACs) has given rise to strategies to clone and catalog the entire human genome. The goal of constructing overlapping YAC clones (contigs) end-to-end across each human chromosome now appears imminent. This development will have immense effect upon our ability to identify disease genes.
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Affiliation(s)
- T C Gilliam
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY
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Ionasescu VV, Trofatter J, Haines JL, Summers AM, Ionasescu R, Searby C. X-linked recessive Charcot-Marie-Tooth neuropathy: clinical and genetic study. Muscle Nerve 1992; 15:368-73. [PMID: 1557086 DOI: 10.1002/mus.880150317] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We describe three families with X-linked recessive Charcot-Marie-Tooth (CMT) neuropathies. The disease phenotype in family 1 was characterized by infantile onset, weakness of lower legs, areflexia, pes cavus, and mental retardation (2 of 5 patients). The disease phenotype in families 2 and 3 was characterized by late onset, distal weakness, and normal intelligence. Hereditary spastic paraparesis was also present in the CMT patients of family 2. Thirty X-linked DNA markers were used for linkage studies. A maximum lod score of +3.48 was obtained by multipoint linkage analysis for the DXS16 locus mapped at Xp22.2 in family 1. In families 2 and 3, there was suggestion of linkage of Xq26 markers; the peak multipoint lod score for these 2 CMT families was 1.81, at DXS144. These results were suggestive of heterogeneity. The joint analysis including both regions (Xp22.2 and Xq26) provided evidence against homogeneity (chi 2 = 9.12, P less than 0.005).
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Affiliation(s)
- V V Ionasescu
- Department of Pediatrics, University of Iowa Hospitals, Iowa City 52242
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Solders G, Andersson T, Persson A. Central conduction and autonomic nervous function in HMSN I. Muscle Nerve 1991; 14:1074-9. [PMID: 1745280 DOI: 10.1002/mus.880141106] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
CNS conduction and autonomic nervous function were investigated in 15 patients with HMSN I. Central motor conduction time (CMCT) was estimated with magnetic brain stimulation and electrical nerve root stimulation. Somatosensory evoked potential (SEP) and visual evoked potential (VEP) were used for assessment of central sensory and visual conduction. Autonomic effector organ functions were assessed with the R-R variation test for parasympathetic function, and the sympathetic skin response test (SSR) for skin sympathetic sudomotor activity. Five of the patients had prolonged CMCT. Central sensory conduction was normal in 3, and slightly prolonged in 1 of the patients, but could not be estimated in 11 due to lack of response from the cervical recording. VEP was abnormal in 2 patients. R-R variations during normal breathing were low in 8 of 15 patients, and low also during deep breathing in 1 of 15. The SSR test was pathological in 5 of 15 patients. Thus, impaired central conduction and/or autonomic dysfunction was not an uncommon finding in patients with HMSN I.
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Affiliation(s)
- G Solders
- Department of Clinical Neurophysiology, Huddinge University Hospital, Sweden
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Mostacciuolo ML, Müller E, Fardin P, Micaglio GF, Bardoni B, Guioli S, Camerino G, Danieli GA. X-linked Charcot-Marie-Tooth disease. A linkage study in a large family by using 12 probes of the pericentromeric region. Hum Genet 1991; 87:23-7. [PMID: 1674715 DOI: 10.1007/bf01213086] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Linkage analysis was performed on 41 subjects belonging to a large family with a recurrence of X-linked Charcot-Marie-Tooth disease (CMTX), by using 12 restriction fragment length polymorphism markers mapping in p11-q13. The results are in agreement with previous linkage data. Three new markers that are potentially useful for genetic analysis of CMTX families are described. A more precise estimate of the localization of the disease locus was attempted by multipoint linkage analysis.
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