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 8

Effects of second-site mutations at the mRNA level (patient 029-01).

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Effects of second-site mutations at the mRNA level (patient 029-01). Oli...
Oligonucleotide primers were similar to those described in Figure 5. A normal human control sample shows the expected 269-bp product (lane 6). The affected skin sample contained 3 additional smaller fragments due to the c.628G→A transition (lanes 1–4 and Figure 5B, c–e). The revertant keratinocytes of biopsy I (R) with the secondary c.619A→C mutation (lane 1) produced more full-length mRNA transcript and fewer 64 and 66 bp–deleted transcripts than mutant keratinocytes (lane 5). This is also seen in the revertant keratinocytes from biopsy II (R) (lane 2) and biopsy III (R) (lane 3) containing the additional c.565-3T→C mutation. In contrast, the revertant keratinocytes of biopsy IV (R) with the second-site c.629-1G→A mutation had a greater abundance of the transcript with the 66-bp deletion (lane 4). Lane M contains a 100-bp molecular size marker and lane 7 a negative control.