Is Charcot Marie Tooth A Form Of MS & Are They Related?

The earliest symptoms of Charcot Marie Tooth disease are a weakness in the foot and leg muscles which give rise to feet and leg muscle atrophy. There can be abnormalities such as high arches, curled toes, and flat fees. They can develop difficulty in walking but rarely require a wheelchair. Hand muscle weakness can also develop and can affect daily activities such as writing, dressing up and turning doorknobs. Charcot Marie Tooth disease patients also have decreased touch and temperature sensations, rarely there can be visual and hearing loss as well.

Is Charcot Marie Tooth A Form Of MS & Are They Related?

There many types of Charcot Marie Tooth disease that are categorized according to the pattern of inheritance and effects on the nerves (CMT1, CMT1A CMT2, CMT4, and CMTX). Type-X Charcot-Marie-tooth disease (CMTX) is one type of Charcot Marie Tooth disease and it’s the second commonest type Charcot Marie Tooth disease and accounts for about 8-15% of all CMT cases. CMTX is caused by a mutation in the GJB1 of the X chromosome which causes a thin myelin layer around the peripheral nerve fibers. This leads to progressive nerve degeneration and causes muscle weakness and reduced sensation mainly in the feet, legs, forearms, and hands. Multiple sclerosis (MS) is one of the commonest acquired inflammatory demyelinating with a prevalence exceeding 1 in 1000. ^{(1) (3)}

There have been many case studies linking CMTX and MS and in one study which involved 70 CMTX patients three patients (two male patients in their 50’s and 60’s respectively and a female patient 47 years) with CMTX had features of MS as well. These three patients have central nervous system demyelination and fulfilled the diagnostic criteria of MS. The exact association between CMTX and MS is not known, much larger studies with more subjects are needed to assess it. The proposed mechanism of MS in CMTX patients is that this inherited peripheral nerve demyelination might trigger an autoimmune reaction against the peripheral nerve myelin sheath. A similar reaction might occur in the central nerves and give rise to MS. However, it is not sure if this immune reaction occurs in the peripheral nerves and then affect the central nerves or if the reaction primarily occurs in the central nervous system. ⁽²⁾

Another case study revealed a 40-year old woman diagnosed with MS and CMT1B, imaging studies confirmed the diagnosis of MS and neurophysiological investigations and family history confirmed the diagnosis if CMT1B. this study also suggests that the association can be due to an immunological process involving TNF-alpha as the possible mechanism underlying the two diseases.

Charcot Marie Tooth disease (CMT) is a common neurological disease that affects about 1 in 2,500 people in the US. It’s an inherited motor and sensory peripheral neuropathy. Charcot Marie Tooth disease usually onset in early childhood or late adulthood but the symptoms become apparent during adolescence or early adulthood. The age of onset and severity of symptoms differ from one individual to another even in the members of the same family. Some people do not have many symptoms and they might not even know they have Charcot Marie Tooth disease but for some other people the muscle weakness can be very severe and can develop life-threatening situations as well. Charcot Marie Tooth disease is not considered a fatal disease as most people live a near-normal life, but some patients develop respiratory muscle weakness which can increase the morbidity and mortality. ^{(3) (4)}

Conclusion

CMTX is not a type of Multiple sclerosis. CMTX is the second commonest type of Charcot Marie Tooth disease which accounts for about 8-15% of all CMT cases. CMTX is caused by a mutation in the X chromosome GJB1 which causes a thin myelin layer around the peripheral nerve fibers. This leads to progressive nerve degeneration and causes muscle weakness and reduced sensation mainly in the feet, legs, forearms, and hands. Multiple sclerosis (MS) is one of the commonest acquired inflammatory demyelinating with a prevalence exceeding 1 in 1000. There are many case reports of patients diagnosed with Charcot Marie Tooth disease types (commonly CMTX) and Multiple sclerosis. Therefore, it is believed that there can be some association with Charcot Marie Tooth disease and MS and CMT can be a risk factor for the development of MS.

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Is Charcot Marie Tooth A Form Of MS & Are They Related?