CMT1A/HNPP (PMP22 dosage via MLPA)
Charcot-Marie-Tooth (CMT) disease, or sensorimotor neuropathy, is the most frequent hereditary neuromuscular disease, with a prevalence of 1/2,500 individuals (Suter and Sherer, 2003).
At the molecular level, CMT is a complex disorder, with at least 1,000 associated genetic variants in some 80 genes (Timmerman et al., 2014). In some wide described series, molecular alteration is identified in 60-70% of patients (80% of the demyelinating forms and 25% of the axonal forms) (Rossor et al., 2015). Approximately 90% of abnormalities are distributed in the PMP22, MPZ, GJB1, and MFN2 genes (DiVicenzo et al., 2015), although this value varies between populations, being particularly lower in regions with a high prevalence of recessive hereditary forms. Forty to fifty percent of CMT cases are demyelinating or type 1 (CMT1), of which 70-80% are caused by the duplication of a region of approximately 1,5 Mb which contains the PMP22 gene (CMT1A).
Hereditary motor neuropathy (HMN) comprises 10% of all hereditary neuropathies, with a diagnosis rate of 20-32% (Bansagi et al., 2017).
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