Autosomal dominant ichthyosis vulgaris

  

This is the most frequent type of ichthyosis and perhaps one of the most frequent genetic conditions. In the US this disease is usually called only "ichthyosis vulgaris" The frequency in the general population (prevalence) is believed to be in the range of 1 in 300 persons. The disease starts in infancy, neonates usually do not show symptoms. Later the parents note that the skin of their child becomes dry and rough and is increasingly covered with small or somewhat bigger whitish sometimes grey scales. If the skin manifestation is more severe the scales can become larger, thicker and also darker. The skin may then look as if many hundred small fields are present on it. The limbs usually are more severely affected than the trunk or the face. The dorsal surfaces of the legs are affected in typical cases. Characteristic for this type of ichthyosis is also that the big body folds namely antecubital folds, axilla, groins, popliteal folds are spared. Palms and soles usually show a somewhat thickened skin. Moreover, skin lines in the palms are accentuated. This is also called ichthyosis hand. An additional feature can be small keratotic papules around hair follicles in particular on the dorsal surface of the upper arm and on the dorsal surfaces and lateral surfaces of the upper legs. The subjective complaints of this ichthyosis are moderate sometimes the dry skin may result in itching.

It has often been reported that autosomal dominant ichthyosis vulgaris is frequently associated with atopic dermatitis (atopic eczema). This is certainly true, but in the research community there is also some discussion whether perhaps atopic eczema in some cases may mimic ichthyosis vulgaris. Both diseases may share a common gene.

The exact molecular cause underlying this disease has not yet been clarified. It is well known however that a protein having the name "Filaggrin" is lacking or is diminished. The function of this protein is to connect fibril-like structures named tonofilaments in the epidermis. These tonofilaments in themselves are composed of keratins and have an important function for the stability of the keratinocytes of the epidermis and form the so-called cytoskeleton of the keratinocytes.

It has to be said that the skin changes in ichthyosis vulgaris can be very variable and in some patients there is only a minimal disease expression. Especially in the summer the disease is often barely visible. These patients would describe their skin condition just as "dry skin".