Epidemiology

Charcot-Marie-Tooth (CMT) disease is the most common inherited neurological disorder, affecting at least 1 in every 2500 people, and as many as 1 in 1200 in some countries.[1][2] The condition affects people of all ages, sexes, and ethnicities, and prevalence is constant throughout the world.

The most common subtype of CMT is CMT1A due to a duplication of PMP22 on chromosome 17, which accounts for 50% of all cases, and for 70% of all demyelinating cases (CMT type 1), leading to a prevalence of 1 in every 5000 people.[3] The second most common subtype is CMT1X due to mutations of GJB1 (connexin 32), which accounts for approximately 10% of all cases, and for 20% of patients with demyelinating conductions in whom the CMT1A duplication has already been excluded.

The most common subtype of axonal CMT (CMT type 2) is CMT2A due to mutations in mitofusin, and, of those with CMT2, 20% to 25% will have CMT2A.[4]

Recessive mutations (CMT type 4) account for 5% to 10% of all cases, but may account for up to 50% of patients who have consanguineous parents.[5]

Hereditary neuropathy with liability to pressure palsies (HNPP) due to a deletion of PMP22 has a prevalence of at least 16 per 100,000, although its subtle features suggest that it is underdiagnosed.[6] One study found HNPP accounted for about 6% of all CMT cases.[7]

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