How Is Charcot Marie Tooth Passed Down & Does It Make You Tired?

Charcot Marie Tooth (CMT) disease is an inherited disease that affects the peripheral motor and sensory nerves. It’s also known as hereditary motor and sensory neuropathy and common neurological disease that affects about 1 in 2,500 people in the US. Charcot Marie Tooth usually onset in early childhood or late adulthood but the symptoms become apparent during adolescence or early adulthood.

How Is Charcot Marie Tooth Passed Down?

The pattern of inheritance of Charcot Marie Tooth changes according to the type of Charcot Marie Tooth. The following table summarizes the inheritance pattern of each type of Charcot Marie Tooth.

An autosomal dominant inheritance pattern means that one copy of the mutated gene should be present to get the disorder. Most Charcot Marie Tooth patients have one parent with the affected gene. In this situation, there is a 50% chance of children getting Charcot Marie Tooth.

An autosomal recessive inheritance pattern means both copies of the mutated gene should be present to get the disorder. In this case, both parents should have the mutated gene and it should be passed down to the child to get Charcot Marie Tooth. If only one gene is passed down then that person becomes a carrier.

In the X-linked dominant inheritance pattern, the mutated gene is located on the X-chromosome. One copy of the mutated gene is sufficient to get the disease. In most the cases, the males are affected more as they only have one X-chromosome and the affected gene will be present in it, whereas in females one X-chromosome would be normal and the other chromosome will have the mutated gene, therefore, females have fewer symptoms. Fathers with the mutated X-chromosome would not pass it down to their sons and all daughters from an affected father will get one mutated chromosome however, the symptoms might not be that severe. ^{(1) (2) (3)}

Sometimes CMT can occur due to new gene mutations especially autosomal dominant and x-linked types of CMT’s.

Does Charcot Marie Tooth Disease Make You Tired?

Respiratory muscle weakness is rare in Charcot Marie Tooth people but some patients get it and this can be a life-threatening situation. The cause for breathing difficulties and tiredness in Charcot Marie Tooth patients is diaphragmatic dysfunction. This occurs when your phrenic nerve is affected which can lead to phrenic nerve palsy and this causes diaphragmatic failure. So, if you regularly feel tired and shortness of breath you should inform your doctor so that the situation can be assessed and further management can be carried out. You need devices that deliver air under pressure to the lungs especially at night. a pressure support ventilator that can be used to improve the symptoms. BiPAP (bilevel or two-level positive airway pressure) and CPAP (continuous positive airway pressure) are two devices that can be used. CPAP delivers a single pressure whereas BiPAP delivers inhale and exhale pressure. BiPAP is best for Charcot Marie Tooth patients. ⁽⁴⁾

Conclusion

The pattern of inheritance of Charcot Marie Tooth changes according to the type of CMT. CMT1, CMT2 are autosomal dominant that means a mutation in one gene is enough to cause CMT. CMT4, CMT2, and CMTDI are autosomal recessive that means a mutation in both genes is needed to cause Charcot Marie Tooth. CMTRI and CMTX are x-linked dominant which means the mutated gene is located on the X-chromosome and one copy of the mutated gene is sufficient to get the disease. Respiratory muscle weakness is rare in Charcot Marie Tooth people but some patients get it and this can be a life-threatening situation. This occurs when the phrenic nerve is affected which can lead to phrenic nerve palsy and this causes diaphragmatic failure leading to poor airway transportation. You need devices that deliver air under pressure to the lungs especially at night. A pressure support ventilator which can be used to improve the symptoms.

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How Is Charcot Marie Tooth Passed Down & Does It Make You Tired?