Prenatal diagnosis of epidermal disorders

Prenatal diagnosis of Sjögren-Larsson syndrome using enzymatic methods

Sjögren-Larsson syndrome (SLS) is an autosomal recessive disorder characterized by the presence of congenital ichthyosis, mental retardation, and spasticity. The primary biochemical defect in SLS has recently been identified to be a deficiency of fatty aldehyde dehydrogenase (FALDH), which is a component of fatty alcohol:NAD+ oxidoreductase (FAO). We monitored four pregnancies at risk for SLS by measuring FAO and FALDH in cultured amniocytes or cultured chorionic villus cells. The enzymatic results in one case using amniocytes obtained during the second trimester predicted an affected SLS fetus, which was confirmed at termination of the pregnancy. Another at-risk fetus was predicted to be affected with SLS using cultured chorionic villus cells obtained in the first trimester, and fetal skin fibroblasts confirmed a profound deficiency of FAO and FALDH. Two other fetuses were correctly predicted to be unaffected. These results demonstrate that SLS can be diagnosed prenatally using enzymatic methods.

All about ichthyosis

From "alligator people" to "porcupine boys," the ichthyoses have been a distinctly recognizable entity for thousands of years. Recent improvements in biochemical and genetic research have allowed more scientific delineation of this class of diseases. This article covers the latest in pathophysiology, the major classes of ichthyoses, many of the newer minor ones, prenatal diagnosis, and treatment options.

Fetal skin biopsy in prenatal diagnosis of some genodermatoses

Various methods of obtaining fetal skin for prenatal diagnosis of certain autosomal-recessive congenital genodermatoses have been assessed. An attempt was made to obtain fetal skin by fetoscopy in 15 patients prior to pregnancy termination for a variety of medical reasons at 18-26 weeks. Specimens were obtained only in five cases (8 successful attempts out of 48). In twelve cases, of which five had a history of a child with junctional (Herlitz type) or dystrophic (Hallopeau-Siemens type) epidermolysis bullosa or non-bullous congenital ichthyosiform erythroderma at 16-25 weeks of pregnancy, fetal skin was obtained without fetoscopy under direct ultrasonic control. Specimens were obtained in all cases (33 successful attempts out of 39). In three cases, fetal pathology was diagnosed by the method of semi-thin and ultra-thin skin sections, and the respective pregnancies were terminated.

Ultrastructure of first trimester chorionic villi with regard to the prenatal diagnosis of genodermatoses

Hopes are held out for chorion villus sampling, a technique which is gaining more and more importance for the first trimester prenatal diagnosis of chromosomal aberrations and metabolic abnormalities. A variety of inherited skin diseases can be diagnosed postnatally and prenatally (in the second trimester) by ultrastructural diagnostic markers. For evaluation of prenatal diagnosis in the first trimester, we investigated chorionic villi derived from the trophoblast layer of the early pregnancy by light microscopy and conventional electron microscopy. The ultrastructure of the cellular layers covering the villi, i.e., the inner cytotrophoblast and the outer syncytiotrophoblast, as well as that of the connective tissue of the inner extraembryonic mesoderm, are thoroughly described in relation to the ultrastructural changes in certain genodermatoses including epidermolyses and keratinization disorders. We found that chorionic villi have only a few of the characteristics differentiated in skin, and none of the structures which are relevant to the diagnosis of genodermatoses. In our view, the ultrastructural approach is not suitable for first trimester prenatal diagnosis of genodermatoses in chorionic villi.