PMC4926754_01
a) Hands and thoracic region showing generalized bullae, scarring and milia
b) Lower legs showing scarring, bullae, milia and characteristic dystrophic nails
c) Pedigree of the family
d) The chromatogram depicting capillary sequencing results of c.6759_6760del in the trio. The mutation loci (DeltaCT) is highlighted with asterisks
e) Domain structure of COL7A1 protein showing Von Willebrand factor type A domain (VWA), Fibronectin type III domain (fn3), collagen triple helix domain (blue) and Kunitz domain (yellow). Each needle represents disease causing variation site and the red needle represent p.G2254fs (c.6759_6760del) variation. Panel at the bottom represents COL7A1 p.G2254fs induced PTC compared to the normal protein.
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The clinical picture ( Figure 1a,b) corroborated the diagnosis of dystrophic epidermolysis bullosa (DEB). Secondary structure analysis shows that p.G2254fs resultant PTC leads to loss of function of several collagen triple helix repeats and kunitz domain ( Figure 1e).