Charcot-Marie-Tooth disease type 1C

Charcot-Marie-Tooth disease type 1C (CMT1C) is a rare, dominantly inherited neuropathy caused by mutations in the lipopolysaccharide-induced tumor necrosis factor-alpha-inducing gene (LITAF). This condition affects the peripheral nerves, leading to progressive weakness and atrophy of muscles.

Characteristics:

• CMT1C is an autosomal dominant disorder, meaning that a single copy of the mutated gene is sufficient to cause the disease.
• It is characterized by abnormalities in myelin, the fatty substance that covers nerve cells, protecting them and helping to transmit signals.
• The condition typically affects individuals in adolescence or adulthood.

Prevalence:

• CMT1C is a rare form of Charcot-Marie-Tooth disease, with an estimated prevalence of less than 1 in 1 million people.

Symptoms:

• Progressive weakness and atrophy of muscles
• Abnormalities in myelin, leading to impaired nerve function

Causes:

• Mutations in the LITAF gene (603795) are responsible for CMT1C.
• Heterozygous mutation in the ITPR3 gene (147267) on chromosome 6p21 can also cause a similar condition, known as CMT1J.

References:

• [1] Charcot-Marie-Tooth disease type 1C is caused by heterozygous mutation in the LITAF gene. (#2)
• [3] Any Charcot-Marie-Tooth disease type 1 in which the cause of the disease is a mutation in the LITAF gene is referred to as CMT1C. (Synonyms: CMT 1C; CMT slow nerve conduction type C) (#3)
• [4] Type 1 (CMT1) is characterized by abnormalities in myelin, which can also be seen in CMT1C. (#4)
• [5] Charcot-Marie-Tooth 1C (CMT1C) is a rare form of dominantly inherited CMT1 neuropathy caused by a mutated gene encoding lipopolysaccharide-induced tumor necrosis factor-alpha-inducing protein. (#5)
• [6] Prevalence and inheritance pattern of CMT1C are mentioned in this reference. (#6)
• [7] Although not directly related to CMT1C, the ITPR3 gene mutation on chromosome 6p21 can cause a similar condition, known as CMT1J. (#7)

Common Signs and Symptoms of Charcot-Marie-Tooth Disease Type 1C

Charcot-Marie-Tooth disease type 1C (CMT1C) is a progressive neuropathy that affects the peripheral nerves, leading to muscle weakness, atrophy, and sensory deficits. The symptoms of CMT1C can vary widely among individuals, but here are some common signs and symptoms:

• Muscle Weakness: Muscle weakness and wasting in the legs and arms are common symptoms of CMT1C [8].
• Sensory Deficits: Sensory deficits, such as tingling, pricking, or numbness of the skin with no apparent physical cause, can occur in the feet and lower legs [3].
• Decreased Sensitivity: Decreased sensitivity to touch, heat, and cold in the feet and lower legs is a typical symptom of CMT1C [3].
• Muscle Atrophy: Muscle atrophy, or wasting, can occur in the affected limbs, leading to changes in muscle tone and strength.
• Ankle Sprains: Repeated ankle sprains can occur due to muscle weakness and atrophy in the legs.
• Sensory Loss: Sensory loss of position, vibration, and pain/temperature commonly occurs in the feet and later in the hands [7].
• Muscle Cramps: Muscle cramps and calf hypertrophy can also be symptoms of CMT1C.

It's essential to note that the symptoms of CMT1C can vary widely among individuals, and not everyone will experience all of these symptoms. If you suspect you or a loved one may have CMT1C, consult with a healthcare professional for proper diagnosis and treatment.

References: [3] - Oct 1, 2018 [7] - [8] -

Diagnostic Tests for Charcot-Marie-Tooth Disease Type 1C

Charcot-Marie-Tooth (CMT) disease is a group of hereditary disorders that affect the peripheral nerves. CMT1C is one subtype of this condition, and diagnosing it requires a combination of clinical evaluation, laboratory tests, and genetic analysis.

Clinical Evaluation A physical examination by a neurologist or a primary care physician can help identify signs and symptoms associated with CMT1C. This may include:

• Muscle weakness, particularly in the distal muscles (those farthest from the center of the body)
• Loss of reflexes
• Sensory disturbances, such as numbness or tingling sensations

Laboratory Tests Several laboratory tests can help confirm a diagnosis of CMT1C:

• Electromyography (EMG): This test measures the electrical activity of muscles and can detect abnormal muscle function.
• Nerve Conduction Studies: These tests measure the speed and strength of nerve impulses, which can be affected in individuals with CMT1C.

Genetic Testing Genetic testing is essential to pinpoint the exact subtype of C

Current Drug Treatment Options for Charcot-Marie-Tooth Disease Type 1C

Charcot-Marie-Tooth disease type 1C (CMT1C) is a rare and inherited disorder that affects the peripheral nerves. While there is no cure for CMT1C, various drug treatments can help manage its symptoms.

• Steroids: A case study published in [8] describes the use of methylprednisolone as an initial treatment approach for a patient with CMT1C. However, it's essential to note that steroids are not a standard treatment for this condition.
• Other medications: There is limited information available on specific drug treatments for CMT1C. In general, management of the disease focuses on symptom relief and rehabilitation therapy.

Current Management Focus

The primary focus of current management strategies for CMT1C is to alleviate symptoms and improve quality of life. This may involve:

• Rehabilitation therapy: Physical therapy, occupational therapy, or speech therapy can help patients with CMT1C maintain their physical abilities and adapt to the condition.
• Surgery: In some cases, surgery may be necessary to address specific complications related to CMT1C.

Research Directions

While there is no established drug treatment for CMT1C, research continues to explore potential therapeutic options. Gene therapy, in particular, holds promise as a possible approach to treating this condition [4].

Key Points

• There is currently no effective drug treatment available for Charcot-Marie-Tooth disease type 1C.
• Management strategies focus on symptom relief and rehabilitation therapy.
• Research into gene therapy may offer potential therapeutic options for CMT1C in the future.

References:

[4] Dong H. (2024) - [5] Orphanet summary about this condition that may include information on diagnosis, care, and treatment as well as other resources.

Charcot-Marie-Tooth (CMT) disease type 1C is a subtype of CMT, which is a genetically heterogeneous group of disorders sharing the same clinical phenotype [7]. The differential diagnosis for CMT type 1C involves distinguishing it from other forms of CMT and similar conditions.

Key Features:

• Slowly progressive, length-dependent weakness, atrophy, and sensory loss in distal limbs [8]
• Reduction or loss of deep tendon reflexes
• Similar clinical symptoms can be produced by mutations in different genes, making CMT a heterogenous genetic disease [6]

Differential Diagnoses:

• Hereditary neuropathy with liability to pressure palsies (HNPP)
• Inflammatory neuropathies, such as chronic inflammatory demyelinating polyneuropathy (CIDP)
• Other forms of CMT, including type 1A and type X

Diagnostic Considerations:

• Genetic testing can help identify the specific mutation responsible for the disease
• Electrophysiological studies, such as nerve conduction studies, can provide evidence of demyelination or axonal loss
• Histopathological examination of sural nerve biopsies may show features of demyelination or axonal degeneration

References:

[6] Type X Charcot-Marie-Tooth disease (CMTX) is a subtype of CMT that can present with similar clinical symptoms to CMT type 1C. [7] Charcot-Marie-Tooth disease (CMT) is a genetically heterogeneous group of disorders sharing the same clinical phenotype, characterized by distal limb muscle weakness and sensory loss. [8] Most forms of Charcot-Marie-Tooth disease have slowly progressive, length-dependent weakness, atrophy, and sensory loss, including reduction or loss of deep tendon reflexes.