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Charcot-Marie-Tooth Neuropathy X Type 5

Synonyms: CMTX5, Rosenberg-Chutorian Syndrome

, MD, PhD and , MD, PhD.

Author Information

Initial Posting: ; Last Update: June 6, 2013.


Clinical characteristics.

X-linked Charcot-Marie-Tooth neuropathy type 5 (CMTX5), part of the spectrum of PRPS1-related disorders, is characterized by peripheral neuropathy, early-onset (prelingual) bilateral profound sensorineural hearing loss, and optic neuropathy. The onset of peripheral neuropathy is between ages five and 12 years. The lower extremities are affected earlier and more severely than upper extremities. Initial manifestations often include foot drop or gait disturbance. Onset of visual impairment is between ages seven and 20 years. Intellect and life span are normal. Carrier females do not have findings of CMTX5.


Diagnosis is based on clinical findings, family history consistent with X-linked inheritance, and identification of a disease-causing mutation in PRPS1, the only gene in which mutations are known to cause CMTX5.


Treatment of manifestations: Peripheral neuropathy, hearing loss, and visual impairment are managed in a routine manner.

Surveillance: Regular neurologic and ophthalmologic evaluations to monitor symptom development and disease progression.

Agents/circumstances to avoid: Medications known to cause acquired peripheral neuropathy.

Evaluation of relatives at risk: It is appropriate to evaluate at-risk males at birth with detailed audiometry to assure early diagnosis and treatment of hearing loss.

Genetic counseling.

CMTX5 is inherited in an X-linked manner. Carrier women have a 50% chance of transmitting the PRPS1 mutation in each pregnancy. Males who inherit the mutation will be affected; females who inherit the mutation will be carriers and typically will not be affected. Males pass the disease-causing mutation to all of their daughters and none of their sons. Carrier testing for at-risk family members and prenatal testing for pregnancies at increased risk are possible if the disease-causing mutation has been identified in the family.


Clinical Diagnosis

X-linked Charcot-Marie-Tooth neuropathy type 5 (CMTX5), part of the spectrum of PRPS1-related disorders, is characterized by the following:

Peripheral neuropathy

  • Motor nerve conduction velocities (NCVs) of affected males reveal delayed distal latencies and decreased amplitudes with relatively normal velocities (median motor NCV ≥38 m/s), consistent with an axonal neuropathy.
  • Compound motor/sensory action potentials are not induced.
  • Needle electromyography (EMG) reveals polyphasic potentials with a prolonged duration and reduced recruitment pattern.

Early-onset sensorineural hearing loss

  • Pure tone audiograms demonstrate bilateral profound sensorineural hearing loss.
  • Auditory brain stem response waveforms may not be obtained.
  • Temporal bone computed tomography reveals no abnormal findings.

Optic neuropathy

  • Fundoscopic examination shows bilateral optic disc pallor, indicating optic atrophy.
  • Visual evoked potentials demonstrate delayed latency and decreased amplitudes of P100.
  • Electroretinogram is normal.


Phosphoribosylpyrophosphate synthetase (PRS) enzyme activity can be analyzed in fibroblasts, lymphoblasts, and erythrocytes [Torres et al 1996].

PRS enzyme activity in three individuals with CMTX5 was decreased compared to controls [Kim et al 2007].

Note: Because it is difficult to assay PRS1 enzyme activity separately from that of the other two isoforms (PRS2 and PRS3), decrease in PRS enzyme activity is assumed to reflect decreased activity of PRS1, not PRS2 or PRS3.

Serum uric acid concentrations measured in three individuals with CMTX5 of Korean descent and two of European descent (originally reported as having Rosenberg-Chutorian syndrome) were within the normal range [Kim et al 2007].

Molecular Genetic Testing

Gene. PRPS1, encoding phosphoribosyl pyrophosphate synthetase I, is the only gene in which mutations are known to cause CMTX5.

Clinical testing

Table 1.

Summary of Molecular Genetic Testing Used in CMTX5

Gene 1Test MethodMutations Detected 2Mutation Detection Frequency by Test Method 3
PRPS1Sequence analysis 4Sequence variants100% 5, 6, 7
Deletion/duplication analysis 8Exonic/whole-gene deletions or duplicationsUnknown 9

See Molecular Genetics for information on allelic variants.


The ability of the test method used to detect a mutation that is present in the indicated gene


Examples of mutations detected by sequence analysis may include small intragenic deletions/insertions and missense, nonsense, and splice site mutations; typically, exonic or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.


Two families reported to date [Kim et al 2007]


Lack of amplification by PCR prior to sequence analysis can suggest a putative exonic, multiexonic, or whole-gene deletion on the X chromosome in affected males; confirmation may require additional testing by deletion/duplication analysis.


Sequence analysis of genomic DNA cannot detect deletion of one or more exons or the entire X-linked gene in a heterozygous female.


Testing that identifies deletions/duplications not readily detectable by sequence analysis of the coding and flanking intronic regions of genomic DNA; included in the variety of methods that may be used are: quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and chromosomal microarray (CMA) that includes this gene/chromosome segment.


No deletions or duplications of PRPS1 have been reported to cause Charcot-Marie-Tooth neuropathy X type 5.

Testing Strategy

To confirm/establish the diagnosis in a proband, identification of a disease-causing mutation in PRPS1 is necessary.

Carrier testing for at-risk relatives requires prior identification of the disease-causing mutation in the family.

Note: (1) Carriers are heterozygotes for this X-linked disorder and are not known to be at risk of developing clinical findings related to the disorder. (2) Identification of female carriers requires either (a) prior identification of the disease-causing mutation in an affected male relative or, (b) if an affected male is not available for testing, molecular genetic testing first by sequence analysis and then, if no mutation is identified, by deletion/duplication analysis.

Prenatal diagnosis and preimplantation genetic diagnosis (PGD) for at-risk pregnancies require prior identification of the disease-causing mutation in the family.

Clinical Characteristics

Clinical Description

The symptom triad of CMTX5 is peripheral neuropathy, sensorineural hearing loss, and optic neuropathy.

The age at onset of symptoms of peripheral neuropathy ranges from five to 12 years. The initial manifestation is often foot drop or gait disturbance. Deep tendon reflexes are usually absent. Motor signs predominate, but impairment of sensory function may accompany motor dysfunction or develop during disease progression. Lower extremities are affected earlier and more severely than upper extremities.

Typically, boys with CMTX5 have early-onset (prelingual) sensorineural hearing loss.

The age at onset of visual impairment ranged from seven to 20 years.

Affected individuals have normal intellect.

Both peripheral neuropathy and optic neuropathy progress with time. With advancing disease, affected individuals may become dependent on crutches or a wheelchair. There is no evidence that life span is shortened in individuals with CMTX5 [Rosenberg & Chutorian 1967, Kim et al 2007].

Carrier females do not have findings of CMTX5.

Sural nerve biopsy demonstrates demyelination and axonal loss. Electron microscopic examination reveals onion bulb formation [Kim et al 2007].

Genotype-Phenotype Correlations

Across the four disease phenotypes included as PRPS1-related disorders, only missense mutations have been reported to date. No correlation is known between specific PRPS1 missense mutations and the phenotypes.


Penetrance is complete for CMTX5.


Prevalence has not been estimated. Two families with CMTX5 have been identified worldwide [Rosenberg & Chutorian 1967, Kim et al 2007].

CMTX5 appears to be very rare; however, it may be underdiagnosed as a result of under-recognition by physicians.

Differential Diagnosis

Peripheral neuropathy. See Charcot-Marie-Tooth Hereditary Neuropathy Overview.

X-linked Charcot-Marie-Tooth disease (CMTX). CMTX5 is clearly distinguishable from the five other forms of X-linked Charcot-Marie-Tooth disease [Kim et al 2005] (see Charcot-Marie-Tooth Neuropathy X Type 1):

Sensorineural hearing loss. It is important to suspect CMTX5 when boys with early-onset sensorineural hearing loss develop gait disturbance and visual disturbance.

See Deafness and Hereditary Hearing Loss Overview.


Evaluations Following Initial Diagnosis

To establish the extent of disease and needs in an individual diagnosed with CMTX5, the following evaluations are recommended:

  • Neurologic examination
  • Pure tone audiograms, auditory brain stem response test
  • Evaluation of visual acuity, fundoscopic examination
  • Medical genetics consultation

Treatment of Manifestations

Peripheral neuropathy. See Charcot-Marie-Tooth Hereditary Neuropathy Overview, Management.

Sensorineural hearing loss. See Deafness and Hereditary Hearing Loss Overview, Management.

Optic atrophy. Use of routine low-vision aids as needed is appropriate.

Prevention of Secondary Complications

Daily heel cord stretching exercises are desirable to prevent Achilles’ tendon shortening from peripheral neuropathy, which can occur in individuals with CMTX5.


Individuals should be evaluated regularly by a team comprising otologists, ophthalmologists, neurologists, physiatrists, and physical and occupational therapists to determine neurologic status and functional disability. While profound hearing loss begins during infancy, optic neuropathy and peripheral neuropathy in CMTX5 vary in age of onset of manifestations and progression. Thus, regular ophthalmologic and neurologic exams are warranted to monitor symptom development and progression.

Agents/Circumstances to Avoid

Obesity is to be avoided because it makes walking more difficult.

Medications that are toxic or potentially toxic to persons with CMT comprise a spectrum of risk ranging from definite high risk to negligible risk. Click here (pdf) for an up-to-date list.

Evaluation of Relatives at Risk

It is appropriate to evaluate at-risk males at birth with detailed audiometry to assure early diagnosis and treatment of hearing loss.

See Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.

Therapies Under Investigation

Dietary S-adenosylmethionine (SAM) supplementation could theoretically alleviate some of the symptoms of Arts syndrome by providing an oral source of purine nucleotide precursor that is not PRPP dependent. Furthermore, SAM is known to cross the blood-brain barrier. An adult with HPRT deficiency is reported to have benefitted neurologically from SAM administration without untoward side effects [Glick 2006].

An open-label clinical trial of SAM in two Australian brothers (ages 14 and 13 in 2010) with Arts syndrome is continuing [J Christodoulou et al, unpublished data; approved by the ethics and drug committees, Children's Hospital at Westmead, Sydney, Australia]. Oral SAM supplementation is presently set at 30 mg/kg/day. The boys appear to have had significant benefit from this therapy based on decreased number of hospitalizations and stabilization of nocturnal BIPAP requirements; however, slight deterioration in their vision has been noted.

Mildly affected carrier females from families with Arts syndrome may also benefit from SAM supplementation in their diet, although this remains to be tested. Whether treatment with SAM supplementation would benefit individuals with allelic disorders (PRS superactivity, Charcot-Marie-Tooth neuropathy X type 5) remains to be investigated.

Search for access to information on clinical studies for a wide range of diseases and conditions.

Genetic Counseling

Genetic counseling is the process of providing individuals and families with information on the nature, inheritance, and implications of genetic disorders to help them make informed medical and personal decisions. The following section deals with genetic risk assessment and the use of family history and genetic testing to clarify genetic status for family members. This section is not meant to address all personal, cultural, or ethical issues that individuals may face or to substitute for consultation with a genetics professional. —ED.

Mode of Inheritance

CMTX5 is inherited in an X-linked manner.

Risk to Family Members

Parents of a male proband

Sibs of the proband

  • The risk to the sibs of a proband depends on the genetic status of the parents:
    • If the mother has a disease-causing mutation, the chance of transmitting the PRPS1 mutation in each pregnancy is 50%. Male sibs who inherit the mutation will be affected; female sibs who inherit the mutation will be carriers and typically will not be affected.
    • If the disease-causing mutation cannot be detected in the DNA of the mother of the only affected male in the family, the risk to sibs is low but greater than that of the general population because of the possibility of germline mosaicism.
  • No instances of germline mosaicism have been reported, but it remains a possibility.

Offspring of a male proband. Males pass the disease-causing mutation to all of their daughters and none of their sons.

Other family members of the proband. If the mother of a proband also has a disease-causing mutation, her female family members may be at risk of being carriers and her male family members may be at risk of being affected depending on their genetic relationship to the proband.

Carrier Detection

Carrier testing is possible if the mutation has been identified in the family.

Related Genetic Counseling Issues

See Management, Evaluation of Relatives at Risk for information on evaluating at-risk relatives for the purpose of early diagnosis and treatment.

Family planning

  • The optimal time for determination of genetic risk, clarification of carrier status, and discussion of the availability of prenatal testing is before pregnancy.
  • It is appropriate to offer genetic counseling (including discussion of potential risks to offspring and reproductive options) to young adults who are affected, are carriers, or are at risk of being carriers.

DNA banking is the storage of DNA (typically extracted from white blood cells) for possible future use. Because it is likely that testing methodology and our understanding of genes, mutations, and diseases will improve in the future, consideration should be given to banking DNA of affected individuals.

Prenatal Testing

If the disease-causing mutation has been identified in an affected family member, prenatal diagnosis for pregnancies at increased risk is possible by analysis of DNA extracted from fetal cells obtained by amniocentesis (usually performed at ~15-18 weeks’ gestation) or chorionic villus sampling (usually performed at ~10-2 weeks’ gestation). Usually fetal sex is determined first and molecular genetic testing is performed if the karyotype is 46,XY.

Note: Gestational age is expressed as menstrual weeks calculated either from the first day of the last normal menstrual period or by ultrasound measurements.

Preimplantation genetic diagnosis (PGD) may be an option for some families in which the disease-causing mutations have been identified.


GeneReviews staff has selected the following disease-specific and/or umbrella support organizations and/or registries for the benefit of individuals with this disorder and their families. GeneReviews is not responsible for the information provided by other organizations. For information on selection criteria, click here.

  • Association CMT France
    Phone: 820 077 540; 2 47 27 96 41
  • Charcot-Marie-Tooth Association (CMTA)
    PO Box 105
    Glenolden PA 19036
    Phone: 800-606-2682 (toll-free); 610-499-9264
    Fax: 610-499-9267
  • Charcot-Marie-Tooth Association of Australia
    Concord Hospital
    Building 51
    Concord New South Wales 2139
    Phone: 02 9767 5105
    Fax: 02 9767 5167
  • European Charcot-Marie-Tooth Consortium
    Department of Molecular Genetics
    University of Antwerp
    Antwerp Antwerpen B-2610
    Fax: 03 2651002
  • Hereditary Neuropathy Foundation, Inc.
    432 Park Avenue South
    4th Floor
    New York NY 10016
    Phone: 855-435-7268 (toll-free); 212-722-8396
    Fax: 917-591-2758
  • My46 Trait Profile
    Institute of Genetic Medicine
    University of Newcastle upon Tyne
    International Centre for Life
    Newcastle upon Tyne NE1 3BZ
    United Kingdom
    Phone: 44 (0)191 241 8617
    Fax: 44 (0)191 241 8770
  • Association Francaise contre les Myopathies (AFM)
    1 Rue de l'International
    Evry cedex 91002
    Phone: +33 01 69 47 28 28
  • European Neuromuscular Centre (ENMC)
    Lt Gen van Heutszlaan 6
    3743 JN Baarn
    Phone: 31 35 5480481
    Fax: 31 35 5480499
  • Muscular Dystrophy Association - USA (MDA)
    222 South Riverside Plaza
    Suite 1500
    Chicago IL 60606
    Phone: 800-572-1717
  • Muscular Dystrophy Campaign
    61A Great Suffolk Street
    London SE1 0BU
    United Kingdom
    Phone: 0800 652 6352 (toll-free); 020 7803 4800
  • RDCRN Patient Contact Registry: Inherited Neuropathies Consortium

Molecular Genetics

Information in the Molecular Genetics and OMIM tables may differ from that elsewhere in the GeneReview: tables may contain more recent information. —ED.

Table A.

Charcot-Marie-Tooth Neuropathy X Type 5: Genes and Databases

Data are compiled from the following standard references: gene from HGNC; chromosome locus, locus name, critical region, complementation group from OMIM; protein from UniProt. For a description of databases (Locus Specific, HGMD) to which links are provided, click here.

Table B.

OMIM Entries for Charcot-Marie-Tooth Neuropathy X Type 5 (View All in OMIM)


Gene structure. PRPS1 is located on the chromosome band Xq21.32-q24 and spans 23 kb with seven exons. Two other PRPS genes have been identified: PRPS2 (OMIM 311860) maps to chromosome Xp22 and PRPS3 (or PRPS1L1; OMIM 611566) maps to chromosome 7 and appears to be transcribed only in testis [Becker 2001]. For a detailed summary of gene and protein information, see Table A, Gene.

Benign allelic variants. Kim et al [2007] described their observation of a synonymous variant, c.447G>A, with an allele frequency of 1.1%, while resequencing PRPS1 in control chromosomes of Korean descent. See Table 3.

Pathogenic allelic variants. Two missense mutations of PRPS1 have been reported in individuals with CMTX5. The p.Glu43Asp mutation was reported in a Korean family with CMTX5 [Kim et al 2007]. The p.Met115Thr mutation was detected in an affected family of European descent, originally reported as having Rosenberg-Chutorian syndrome [Rosenberg & Chutorian 1967, Kim et al 2007]. See Table 3.

Table 3.

PRPS1 Allelic Variants Discussed in This GeneReview

Class of Variant AlleleDNA Nucleotide ChangeProtein Amino Acid Change
(Alias 1)
Reference Sequences
Benignc.447G>A 2(Pro149Pro)NM_002764​.3

Note on variant classification: Variants listed in the table have been provided by the authors. GeneReviews staff have not independently verified the classification of variants.

Note on nomenclature: GeneReviews follows the standard naming conventions of the Human Genome Variation Society (www​ See Quick Reference for an explanation of nomenclature.

1. Variant designation that does not conform to current naming conventions

2. Observed with an allele frequency of 1.1% (2/185) in control chromosomes of Korean descent [Kim et al 2007]

Normal gene product. PRPS1 encodes a 318-amino acid protein, the PRPS1 (phosphoribosyl pyrophosphate synthetase 1) enzyme. The enzyme catalyzes the phosphoribosylation of ribose 5-phosphate to 5-phosphoribosyl-1-pyrophosphate, which is necessary for the de novo and salvage pathways of purine and pyrimidine biosynthesis.

Abnormal gene product. Four loss-of-function missense mutations have been reported in PRPS1: two in CMTX5 (Table 3), and two in Arts syndrome. The PRS enzyme activity was shown to be decreased in cells of affected males [de Brouwer et al 2007, Kim et al 2007].


Literature Cited

  1. Becker MA. Phosphoribosylpyrophosphate synthetase and the regulation of phosphoribosylpyrophosphate production in human cells. Prog Nucleic Acid Res Mol Biol. 2001;69:115–48. [PubMed: 11550793]
  2. Cowchock FS, Duckett SW, Streletz LJ, Graziani LJ, Jackson LG. X-linked motor-sensory neuropathy type-II with deafness and mental retardation: a new disorder. Am J Med Genet. 1985;20:307–15. [PubMed: 3856385]
  3. de Brouwer AP, Williams KL, Duley JA, van Kuilenburg AB, Nabuurs SB, Egmont-Petersen M, Lugtenberg D, Zoetekouw L, Banning MJ, Roeffen M, Hamel BC, Weaving L, Ouvrier RA, Donald JA, Wevers RA, Christodoulou J. Arts syndrome is caused by loss-of-function mutations in PRPS1. Am J Hum Genet. 2007;81:507–18. [PMC free article: PMC1950830] [PubMed: 17701896]
  4. Glick N. Dramatic reduction in self-injury in Lesch-Nyhan disease following S-adenosylmethionine administration. J Inherit Metab Dis. 2006;29:687. [PubMed: 16906475]
  5. Huttner IG, Kennerson ML, Reddel SW, Radovanovic D, Nicholson GA. Proof of genetic heterogeneity in X-linked Charcot-Marie-Tooth disease. Neurology. 2006;67:2016–21. [PubMed: 17159110]
  6. 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. [PubMed: 1557086]
  7. Ionasescu VV, Trofatter J, Haines JL, Summers AM, Ionasescu R, Searby C. Heterogeneity in X-linked recessive Charcot-Marie-Tooth neuropathy. Am J Hum Genet. 1991;48:1075–83. [PMC free article: PMC1683112] [PubMed: 1674639]
  8. Kennerson ML, Yiu EM, Chuang DT, Kidambi A, Tso SC, Ly C, Chaudhry R, Drew AP, Rance G, Delatycki MB, Züchner S, Ryan MM, Nicholson GA. A new locus for X-linked dominant Charcot-Marie-Tooth disease (CMTX6) is caused by mutations in the pyruvate dehydrogenase kinase isoenzyme 3 (PDK3) gene. Hum Mol Genet. 2013;22:1404–16. [PMC free article: PMC3596851] [PubMed: 23297365]
  9. Kim HJ, Hong SH, Ki CS, Kim BJ, Shim JS, Cho SH, Park JH, Kim JW. A novel locus for X-linked recessive CMT with deafness and optic neuropathy maps to Xq21.32-q24. Neurology. 2005;64:1964–7. [PubMed: 15955956]
  10. Kim HJ, Sohn KM, Shy ME, Krajewski KM, Hwang M, Park JH, Jang SY, Won HH, Choi BO, Hong SH, Kim BJ, Suh YL, Ki CS, Lee SY, Kim SH, Kim JW. Mutations in PRPS1, which encodes the phosphoribosyl pyrophosphate synthetase enzyme critical for nucleotide biosynthesis, cause hereditary peripheral neuropathy with hearing loss and optic neuropathy (cmtx5). Am J Hum Genet. 2007;81:552–8. [PMC free article: PMC1950833] [PubMed: 17701900]
  11. Liu X, Han D, Li J, Han B, Ouyang X, Cheng J, Li X, Jin Z, Wang Y, Bitner-Glindzicz M, Kong X, Xu H, Kantardzhieva A, Eavey RD, Seidman CE, Seidman JG, Du LL, Chen ZY, Dai P, Teng M, Yan D, Yuan H. Loss-of-function mutations in the PRPS1 gene cause a type of nonsyndromic X-linked sensorineural deafness, DFN2. Am J Hum Genet. 2010;86:65–71. [PMC free article: PMC2801751] [PubMed: 20021999]
  12. Priest JM, Fischbeck KH, Nouri N, Keats BJ. A locus for axonal motor-sensory neuropathy with deafness and mental retardation maps to Xq24-q26. Genomics. 1995;29:409–12. [PubMed: 8666389]
  13. Rinaldi C, Grunseich C, Sevrioukova IF, Schindler A, Horkayne-Szakaly I, Lamperti C, Landouré G, Kennerson ML, Burnett BG, Bönnemann C, Biesecker LG, Ghezzi D, Zeviani M, Fischbeck KH. Cowchock syndrome is associated with a mutation in apoptosis-inducing factor. Am J Hum Genet. 2012;91:1095–102. [PMC free article: PMC3516602] [PubMed: 23217327]
  14. Rosenberg RN, Chutorian A. Familial opticoacoustic nerve degeneration and polyneuropathy. Neurology. 1967;17:827–32. [PubMed: 6069085]
  15. Torres RJ, Mateos FA, Puig JG, Becker MA. Determination of phosphoribosylpyrophosphate synthetase activity in human cells by a non-isotopic, one step method. Clin Chim Acta. 1996;245:105–12. [PubMed: 8646809]

Chapter Notes

Revision History

  • 6 June 2013 (me) Comprehensive update posted live
  • 18 January 2011 (cd) Revision: additions to therapies under investigation
  • 23 September 2010 (cd) Revision: prenatal testing available clinically
  • 10 June 2010 (cd) Revision: edits to agents and circumstances to avoid
  • 26 August 2008 (cg) Review posted live
  • 3 June 2008 (jwk) Original submission
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