Charcot-Marie-Tooth Disease
From Iusmgenetics
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===Etiology=== | ===Etiology=== | ||
| - | *The ''' | + | *The '''pmp22 gene is duplicated in 70-80% of cases of CMT1''' |
| - | *'''Duplication is facilitated by repeat sequences | + | **The PMP22 gene is on ch 17. |
| + | *'''Duplication is facilitated by repeat sequences flanking the pmp22 gene''' which lead to misalignment and duplication. | ||
===Pathogenesis=== | ===Pathogenesis=== | ||
Current revision as of 13:23, 28 November 2011
Contents |
[edit] Charcot-Marie-Tooth Disease
[edit] General background information
- Charcot-Marie-Tooth disease is also known as "Hereditary motor and sensory neuropathy" (HMSN)
[edit] Mode of inheritance
- There are dominant and recessive types
- Hereditary motor and sensory neuropathy demonstrates variable expressivity
- Type 1 is autosomal dominant (CMT1)
[edit] Single important gene
- The PMP22 gene codes for the structural protein of PNS myelin
[edit] Etiology
- The pmp22 gene is duplicated in 70-80% of cases of CMT1
- The PMP22 gene is on ch 17.
- Duplication is facilitated by repeat sequences flanking the pmp22 gene which lead to misalignment and duplication.
[edit] Pathogenesis
- Segmental demyelination peripheral nerves
- Demyelination results in altered nerve conduction velocities, hypertrophic changes and "onion bulb" formation
- Altered nerve
[edit] Phenotypic information
- Slowly progressive distal wasting and weakness
- First in legs: difficulty walking, loss of reflexes, loss of sensation in toes
- Later in arms
