[Antenatal diagnosis of hereditary epidermolysis bullosa]

Among the genetic disorders of the skin, the heterogeneous group of epidermolysis bullosa includes some of the most severe. Prenatal diagnosis is of considerable importance to the families who have had an affected child, or in which one of the parents is affected. The prenatal diagnosis is performed using fetoscopy and fetal skin biopsy. Fetal skin samples are taken at 20 weeks of gestation and are examined by light and electron microscopy to determine whether the fetus is affected. We report here the French experience on prenatal diagnosis of the severe inherited epidermolysis bullosae. Given the severity and frequency of Herlitz syndrome, it is not surprising that this is the most frequently encountered disease in our series of prenatal diagnosis (14 of 21 epidermolysis bullosae), followed by Hallopeau-Siemens (6 cases), and Pasini type (1 case). Our exclusion diagnosis of a Pasini fetus was the first prenatal diagnosis of this type of epidermolysis bullosa performed and reported in the literature. We stress here in this paper that observing the site of separation in the epidermal dermal junction is not sufficient to make a positive prenatal diagnosis. Prenatal diagnosis depends on the observation of the specific ultrastructural marker of the disease such as: hypoplasia and absence of hemidesmosomes and sub-basal dense plate in junctional epidermolysis bullosa-Herlitz, collagenolysis in recessive dystrophic epidermolysis bullosa-Hallopeau-Siemens, and absence and hypoplasia of anchoring fibrils in dominant dystrophic epidermolysis bullosa-Pasini. Until biochemical defects are clarified and suitable tests become available, electron microscopy remains the only current means for reliable, genetically useful, diagnosis of epidermolysis bullosa. In 62 per cent of cases of our series a prenatal diagnosis of exclusion of disease was made and we would stress that in high risk families repeated fetoscopies for prenatal diagnosis are possible in consecutive pregnancies thus allowing the family to have only normal children.