Progress in Clinical Neurosciences: Charcot-Marie-Tooth Disease and Related Inherited Peripheral Neuropathies

Table 1: Dyck and Lambert classification of hereditary motor and sensory neuropathy (HMSN)[5]

Neuropathy Type	Key Neuropathy Features
HMSN I	Autosomal dominant inheritance with low NCV*
HMSN II	Autosomal dominant inheritance with normal or low normal NCV
HMSN III	Probable autosomal recessive with very low NCV and very severe clinical abnormality
HMSN IV	Refsum's syndrome
HMSN V	Neuropathy with spastic paraplegia
HMSN VI	Neuropathy with optic atrophy
HMSN VII	Neuropathy with retinitis pigmentosa
*Nerve conduction velocity

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Table 2: Current classification of Charcot-Marie-Tooth disease and related neuropathies

Neuropathy Type	Key Neuropathy Features
CMT 1	Dominantly inherited with low NCV*
CMT 2	Dominantly inherited with normal or low normal NCV
CMT X	X-linked inherited
HNPP**	Dominantly inherited with focal nerve lesions
Dejerine-Sottas syndrome	Variable inheritance with very low NCV and severe disability
Congenital Hypomyelination	Sporadic inheritance with extremely low NCV and extremely severe disability
CMT 4	Recessively inherited CMT
*Nerve conduction velocity, **Hereditary Neuropathy with Liability to Pressure Palsies

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Table 3: Neuropathies associated with inherited myelin gene defects

Myelin Gene Defect	Neuropathy
PMP22 duplication homozygous duplication deletion point mutation	PMP22 CMT 1A DSS HNPP DSS
Myelin P0 point mutation	CMT 1B DSS CH
Connexin-32 point mutation	CMT X
EGR2 point mutation	CMT 1 DSS CH
Abbreviations used: Charcot-Marie-Tooth (CMT), Dejerine-Sottas syndrome (DSS), congenital hypomyelination (CH), peripheral myelin protein 22 (PMP22), hereditary neuropathy with liability to pressure palsies (HNPP), early growth response 2 (EGR2)

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