Genetics of Charcot Marie Tooth (CMT) - Modifiers of CMT1A, New Causes of CMT2 (INC-6602)
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ClinicalTrials.gov Identifier: NCT01193088 |
Recruitment Status :
Recruiting
First Posted : September 1, 2010
Last Update Posted : August 18, 2021
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Condition or disease |
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Charcot-Marie-Tooth Disease, Type Ia (Disorder) HMSN |
Study Type : | Observational |
Estimated Enrollment : | 1050 participants |
Observational Model: | Cohort |
Time Perspective: | Prospective |
Official Title: | Genetics of Charcot Marie Tooth Disease (CMT) - Modifiers of CMT1A, New Causes of CMT |
Actual Study Start Date : | May 2010 |
Estimated Primary Completion Date : | December 2022 |
Estimated Study Completion Date : | December 2022 |

Group/Cohort |
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CMT1A
Families/people with genetically defined CMT1A
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Genetically undefined CMT
Families/people with genetically undefined CMT with common causes ruled out.
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- Charcot Marie Tooth disease type 1A (CMT1A) gene modifiers [ Time Frame: once ]While the same genetic change - an extra copy of PMP22 - causes CMT1A by definition, it is unclear why some people have more severe symptoms and some have less severe. We are looking for genetic modifiers - changes in the DNA that may be causing the differences in symptoms.
- New genetic causes of CMT [ Time Frame: Once ]At least 33% of people with CMT have an unknown or genetically un-found form of the condition. We are looking for additional genes that cause CMT when mutated.
Biospecimen Retention: Samples With DNA

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.
Ages Eligible for Study: | Child, Adult, Older Adult |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | Yes |
Sampling Method: | Non-Probability Sample |
Inclusion Criteria:
Patient MUST be seen in person at one of the clinical sites involved in this study.
Charcot Marie Tooth disease type 1A (CMT1A) modifier gene study
- Patient has a documented PMP22 duplication OR
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Patient has a first or second degree relative (parent, child, sibling, half-sibling, aunt, uncle, grandparent, grandchild, niece, or nephew) with a documented PMP22 duplication AND a clear link between that family member and the affected patient AND a phenotype consistent with CMT1A.
i. A clear link is necessary for a second-degree relative. For example, if a grandparent is affected and has a PMP22 duplication, and the parent does not have any signs, symptoms, or electrophysiology consistent with CMT1A, there is no clear link.
ii. In cases where clear links are not available, genetic testing is required for the patient or the first degree family member who is not clearly affected.
AND
- Patient has agreed to take part in the study and has signed a consent form.
- A teenager (ages 13-17) considering enrolling must agree to take part in the study and sign an assent form
Inclusion Criteria - CMT Exome Project
- Patient has demonstrated neuropathy on nerve conduction studies or a clinically diagnosed genetic neuropathy.
- Patient or first or second degree family member with a clear link as described in the CMT1A Inclusion Criteria part b has had negative MFN2 genetic testing, if has an axonal form of CMT (nerve conductions greater than 38 m/s) or negative testing for PMP22 duplication, deletion, sequencing, MPZ, and GJB1 if a demyelinating form of CMT is present (<38 m/s).
- More than one family member is willing eligible to participate.
i. Sample pedigrees showing optimal degrees of relationship are shown below. ii. Participation includes being able to complete all aspects of the study, including the giving informed consent, having a brief physical examination, and providing a DNA sample.
d. Patient has agreed to take part in the study and has signed a consent form. e. A teenager (ages 13-17) considering enrolling must agree to take part in the study and sign an assent form.
Inclusion Criteria - Controls
- Person does not have a peripheral neuropathy, as determined by the investigator.
- Person has understood the study and signed an IRB approved consent form. Teenagers (age 13-17 years) must sign an assent form.
Exclusion Criteria:
- Patient does not wish to participate or does not sign a consent form.
- For CMT Exome Project, patient has a genetically confirmed form of CMT (i.e. mutation in MFN2 causing CMT2A, mutation in GARS causing CMT2D, etc.).
- Known neuropathy from a non-genetic source, such as chemotherapies (i.e. Vincristine, Taxol, Cisplatin), diabetes, alcoholism will be evaluated independently so that genetic contributions to their effects on CMT1A phenotypes can also be analyzed.

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01193088
Contact: Shawna Feely, MS, CGC | 319-384-6362 | UICMTClinic@uiowa.edu | |
Contact: Tiffany Grider, MS, CGC | 319-384-6362 | UICMTClinic@uiowa.edu |

Principal Investigator: | Michael E Shy, MD | University of Iowa |
Publications of Results:
Responsible Party: | Michael Shy, Professor, University of Iowa |
ClinicalTrials.gov Identifier: | NCT01193088 |
Other Study ID Numbers: |
INC-6602 1U54NS065712-01 ( U.S. NIH Grant/Contract ) |
First Posted: | September 1, 2010 Key Record Dates |
Last Update Posted: | August 18, 2021 |
Last Verified: | August 2021 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Yes |
Plan Description: | De-identified RDCRN data is submitted to an ORDR-designated repository. For the current grant cycle, that repository has been dbGaP |
Supporting Materials: |
Study Protocol Statistical Analysis Plan (SAP) Informed Consent Form (ICF) Clinical Study Report (CSR) Analytic Code |
Time Frame: | (For Observational/Longitudinal/Natural History/Epidemiology studies): For the current grant cycle, available data will be released to the repository and will become available to the scientific community one year after publication of planned analyses, or after a period of 5 years from the date when the data were collected, whichever comes first. |
Access Criteria: | - For the current grant cycle, once de-identified data is posted on dbGaP, a summary of the study is posted and individual participant data is accessed via a request through dbGaP. |
URL: | https://www.ncbi.nlm.nih.gov/gap |
CMT CMT1A |
Tooth Diseases Charcot-Marie-Tooth Disease Nerve Compression Syndromes Hereditary Sensory and Motor Neuropathy Stomatognathic Diseases Nervous System Malformations Nervous System Diseases |
Heredodegenerative Disorders, Nervous System Neurodegenerative Diseases Polyneuropathies Peripheral Nervous System Diseases Neuromuscular Diseases Congenital Abnormalities Genetic Diseases, Inborn |