Charcot-Marie-Tooth disease is a group of disorders called hereditary sensory and motor neuropathies that affect the peripheral nerves. Peripheral nerves connect the brain and spinal cord to muscles and to sensory cells that detect sensations such as touch, pain, heat, and sound. Affected individuals experience weakness and atrophy of the muscles in the feet and/or hands.
The disease is usually diagnosed in adolescence or early adulthood, but the symptoms of Charcot-Marie-Tooth disease vary in severity and age of onset even among members of the same family. Most have a moderate physical disability and life expectancy is usually not altered. It is the most common peripheral neuropathy with a frequency of affected individuals 1/3300.
Charcot‐Marie‐Tooth disease is further divided into 4 subtypes (CMT1, CMT2, CMT4 and CMTX).
CΜΤ, type 1Α
CMT, type 1A is the most common type of the disease, comprising 50-60% of cases and presents with autosomal dominant inheritance. It is caused by a heterozygous 1.5-Mb duplication at 17p11.2 that includes PMP22 gene and in rare cases by mutations in the same gene. On the other hand, deletion of PMP22 gene leads to the development of another neuropathy called hereditary neuropathy with liability to pressure palsies (HNPP).
CMTΧ1 is the second most common type of the disease accounting for 10-20% of cases and is inherited in an X-linked pattern. It is caused by mutations in GJB1 gene located on chromosome Xq13.1.
CMT disease has a great genetic heterogeneity. More than 50 genes have been associated to other less common types of Charcot‐Marie‐Tooth and other similar neuropathies. These genes are analysed using a targeted gene panel through Next Generation Sequencing methodology.
CΜΤ, type 1A: Detection of deletions and duplications of the region 17p11.2 including PMP22 gene is carried out using the MLPA technique. CΜΤ, X-linked: Sequencing of GJB1 gene in Genetic Analyser. Other types of CMT: Targeted gene panel using Next Generation Sequencing
Sample type: Peripheral blood in EDTA
Time to result: 2 weeks CMT, type 1A and CMT, X-linked, 4 weeks for the extended gene panel
Prenatal diagnosis for Charcot-Marie-Tooth disease is possible, please contact us for more information.