Epidermolysis bullosa (EB) is caused by mutations in as many as 19 distinct genes. We have developed a next generation sequencing (NGS) panel targeting genes known to be mutated in EB. This panel includes CD151, encoding a transmembrane tetraspanin CD151 expressed in keratinocytes. The NGS panel was applied to a cohort of 92 consanguineous families, consisting of 134 individuals of unknown subtype of EB. To direct the bioinformatics analysis to appropriate candidate genes, we applied a genome-wide homozygosity mapping with a SNPbased array consisting of 550,000 markers. In one family, a homozygous CD151 mutation (NM_139029; c.351+2T>C) at the canonical splice junction at intron 4/exon 5 border was identified, predicting aberrant splicing. RT-PCR confirmed deletion of the entire exon 5 consisting of 75 bp and encoding 25 amino acids. The in-frame deletion resides within the third transmembrane domain of CD151, suggesting aberrant membrane targeting of the protein. Immunofluorescence of skin and Western analysis with a monoclonal antibody revealed the absence of the CD151 epitope. Transmission electron microscopy showed intracellular disruption and cell-cell dysadhesion of keratinocytes in the lower epidermis. Clinical examination of the 35-year old proband revealed widespread blistering, particularly on pretibial areas, nail dystrophy and early onset alopecia, as well as esophageal webbing and strictures. The patient also had history of nephropathy with proteinuria. Collectively, the results provide evidence of a distinct form of EB with systemic involvement. The results suggest that CD151 should be considered as the 20th causative, EB-associated gene.

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