Missense and Inframe Pathogenic Variants in PLEC Lead to Minimal or Delayed-Onset Muscular Dystrophy in Autosomal Recessive Epidermolysis Bullosa Simplex: A Genotype–Phenotype Correlation in Nine Cases

Plectin (PLEC) is a versatile linker protein expressed in nearly all mammalian tissues, interlinking various components of the cytoskeleton and anchoring the hemidesmosome to the intermediate filament network of basal keratinocytes. Variants in PLEC disrupt its function as a linker protein, resulting in epidermolysis bullosa simplex (EBS), a hereditary skin disorder characterized by blister formation and mechanical fragility. Additionally, EBS patients with PLEC variants often exhibit varying degrees of muscular dystrophy. In this study, we detail the genotype, phenotype, transmission electron microscopy (TEM), and immunofluorescence microscopy (IFM) findings of nine Taiwanese EBS patients with PLEC variants. The patients had 13 pathogenic variants, including two missense variants and one inframe variant. Analyzing muscle involvement, TEM, and IFM findings, we determined that the presence of at least one missense or inframe pathogenic variant was correlated with milder muscular dystrophy or a later onset. Using AlphaFold, we modeled the 3D protein structures to elucidate the structural and functional implications of these pathogenic variants.