Charcot-Marie-Tooth type 2 (CMT2) is a peripheral axonal neuropathy hereditary, characterized by muscle wasting and weakness, loss of sensitivity and velocities near normal nerve conduction. This type of neuropathy is not demyelinating.
Charcot-Marie-Tooth type 2 had similar clinical findings against CMT1. However, the two differ in that the CMT1 carries the thickening of nerve trunks, palpable or visible.
Have been identified 15 major genes that cause the different variants of CMT2: CMT2A1 (caused by alterations in KIF1B), CMT2A2 (MFN2), CMT2B (RAB7A), CMT2B1 (LMNA), CMT2B2 (MED25), CMT2C (TRPV4), CMT2D (GARS), CMT2E/1F (NEFL), CMT2F (HSPB1), CMT2I / J (MPZ), CMT2H / K (GDAP1), CMT2L (HSPB8), CMT2N (AARS), CMT2O (Dync1h1) y CMT2P (LRSAM1).
Mutations in GJB1, MFN2 and MPZ genes are the cause of 20-25% of reported cases. Because the genetic heterogeneity of this disease in the case of finding no alteration in these three genes, one can proceed to the analysis of other genes less frequent. TRPV4 and GDAP1 gene sequencing is appropriate when the patient have CMT2 with vocal cord paralysis. GJB1 gene analysis is not required if there is no transmission of the disease in the family of man to man, as it presents a way of X-linked inheritance.
Although the onset of the disease can vary from childhood to adulthood, CMT2 becomes symptomatic in most cases, five to twenty five years. The characteristic symptoms are weakness in the ankles and foot dorsiflexion, depressed or absent tendon reflexes and weakness in the feet. However, tendon reflexes of the upper limbs and associated muscles tend to remain intact.
To learn more about the different variants of CMT2, you can access them from our search engine.