"Sporadic" dystrophic epidermolysis bullosa: a new dominant or mitis recessive mutation?

We describe a case of dystrophic epidermolysis bullosa which occurred in a young boy who presented thickened and dystrophic nails both in hands and feet, atrophic scars on the elbows and knees, some large bullae and milia on the hands and ankles. The parents were clinically unaffected and the family medical history was negative for blistering disease. The immunofluorescence for type VII collagen was positive, yet low in intensity and the number of anchoring fibrils was reduced, as revealed by transmission electron microscopy. The diagnosis of a "sporadic" case of dominant dystrophic epidermolysis bullosa was suggested, although a mitis case of recessive dystrophic epidermolysis bullosa cannot be excluded on the basis of clinical, immunofluorescent and ultrastructural examination. However recent studies, carried out in a series of seemingly sporadic cases, have pointed out the possibility of inheritance of two mutant alleles from unaffected parents. This implies that 'mild' recessive dystrophic epidermolysis bullosa is commoner than once thought. This information is important for genetic counselling and determination of recurrence risk in the present and future generations.