Hemidesmosome heterogeneity in junctional epidermolysis bullosa revealed by morphometric analysis.

In order to examine the claim for a numerical and structural abnormality of the hemidesmosomes in junctional epidermolysis bullosa (JEB), a morphometric analysis of unseparated dermal-epidermal junction was undertaken in 11 subjects with JEB. Of these, 5 died in infancy with "lethal" disease, 3 were children still alive at 1-6 years with "indeterminate" disease, and 3 were females aged 20-60 years with variable phenotypic expression of "nonlethal" JEB. All the lethal cases had reduced numbers of hemidesmosomes which were small and lacked normal subbasal dense plates, with the exception of 1 patient whose hemidesmosomes were structurally and numerically normal. The principal hemidesmosome abnormality in the 3 cases with indeterminate JEB was the absence of normal subbasal dense plates. In 2 of the 3 cases of nonlethal JEB, the hemidesmosomes appeared normal, whereas in the third patient they showed a similar abnormality to that present in the majority of the lethal group. These results demonstrate that JEB is an ultrastructurally heterogeneous condition, and suggest that, even though the hemidesmosome abnormalities may be of diagnostic value, they do not correlate sufficiently well with the clinical outcome to be useful as a prognostic indicator.