Revertant mosaicism in junctional epidermolysis bullosa due to multiple correcting second-site mutations in LAMB3
Anna M.G. Pasmooij, … , Maria C. Bolling, Marcel F. Jonkman
Anna M.G. Pasmooij, … , Maria C. Bolling, Marcel F. Jonkman
Published May 1, 2007
Citation Information: J Clin Invest. 2007;117(5):1240-1248. https://doi.org/10.1172/JCI30465.
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Research Article

Revertant mosaicism in junctional epidermolysis bullosa due to multiple correcting second-site mutations in LAMB3

Abstract

Revertant mosaicism due to in vivo reversion of an inherited mutation has been described in the genetic skin disease epidermolysis bullosa (EB) for the genes KRT14 and COL17A1. Here we demonstrate the presence of multiple second-site mutations, all correcting the germline mutation LAMB3:c.628G→A;p.E210K, in 2 unrelated non-Herlitz junctional EB patients with revertant mosaicism. Both probands had a severe reduction in laminin-332 expression in their affected skin. Remarkably, the skin on the lower leg of patient 078-01 (c.628G→A/c.1903C→T) became progressively clinically healthy, with normal expression of laminin-332 on previously affected skin. In the other proband, 029-01 (c.628G→A/c.628G→A), the revertant patches were located at his arms, shoulder, and chest. DNA analysis showed different second-site mutations in revertant keratinocytes of distinct biopsy specimens (c.565-3T→C, c.596G→C;p.G199A, c.619A→C;p.K207Q, c.628+42G→A, and c.629-1G→A), implying that there is not a single preferred mechanism for the correction of a specific mutation. Our data offer prospects for EB treatment in particular cases, since revertant mosaicism seems to occur at a higher frequency than expected. This opens the possibility of applying revertant cell therapy in mosaic EB of the LAMB3 gene by using autologous naturally corrected keratinocytes, thereby bypassing the recombinant gene correction phase.

Authors

Anna M.G. Pasmooij, Hendri H. Pas, Maria C. Bolling, Marcel F. Jonkman

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Figure 4

Identification of the different correcting LAMB3 mutations in patient 078-01.

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Identification of the different correcting LAMB3 mutations in patient 07...
(A) The G→A nucleotide change at position –1 of the 5ι splice site of intron 7 was present in keratinocytes with reduced staining of LM-332. (B) The second-site mutation c.596G→C was present in revertant keratinocytes of biopsy III (R). (C) An additional mutation in intron 7, c.628+42G→A, in revertant keratinocytes of biopsy IV (R). The cryptic splice site, CAGïΣΦGT, which is used when the c.628+42G→A substitution is present, is indicated by the dashed line. Red arrows indicate the inherited mutation, and green arrows the second-site mutations. Corresponding amino acid sequences are indicated above the nucleotide sequences.