Identification and Targeted Correction of a Pathogenic PMP22 Deep Intronic Variant

Pathogenic variants in the PMP22 gene can lead to hereditary peripheral demyelinating neuropathies of varying severity, including hereditary neuropathy with liability to pressure palsies (HNPP), Charcot–Marie–Tooth disease types 1A and 1E (CMT1A, CMT1E), Roussy–Lévy syndrome, and Dejerine–Sottas disease (DSS). This study describes a novel deep intronic variant c.179-2809A>G in the PMP22 gene, identified in two unrelated Avar families from Dagestan republic, Russia. This variant was identified in nine patients. In seven cases, it was detected in a heterozygous state, leading to the development of HNPP. In two cases, this variant was found in a homozygous state, resulting in a more severe CMT1A phenotype (Dejerine–Sottas disease). The performed functional analysis allowed us to characterize the deleterious effect of this variant and propose an approach for personalized antisense therapy. This work demonstrates that, in Avar people with HNPP traits, variant c.179-2809A>G should be considered as disease-causing and included in standard genetic testing.