Ichthyosis vulgaris (IV) is the commonest of the inherited or genetic ichthyoses. It occurs in roughly 1 in 250 people and equally in males and females. Like many diseases due to an abnormal gene it can be passed on from one generation to the next, from an affected person to his or her child. It is usually mild and may occur with eczema.
How do I recognise IV?
The skin may be dry and scaly within the first two months of life, although it may not appear until school age, especially in warmer climates. The scale is white or grey, small and flaky and semi-stuck on with turned up edges. It is most obvious on the outside surfaces of the arms and lower legs and usually there is no scaling in the joint creases. The tummy and flanks are mildly affected. Fine scaling on the face and ears can occur at times and the palms and soles, while free of scale, do have more skin lines than usual. Rough, dry skin on the arms and thighs (keratosis pilaris) is common and as mentioned, itchy eczema may co-exist in the affected person. The joint creases tend to show signs of the eczema but not the ichthyotic scaling.
The scaling of IV is more marked in wintertime cold weather in most patients and it can completely clear in warm and sunny weather. Many sufferers notice a gradual improvement in their teens onwards.
Are investigations needed?
A skin biopsy is not necessary although it does show typical changes under the microscope. Biochemical research has revealed an abnormality in an important structural protein of the skin which is profilaggrin. The link between this and the visible scaling is not known but the resulting chemical imbalance seems to reduce the ability of skin to hold water or humidity and affects the protective barrier of the skin surface.
How is it inherited?
The abnormal gene causing IV is one of a pair of matched genes which play a part in skin development and function. The matching normal gene cannot prevent the defect caused by the abnormal gene of the pair and so it is referred to as a dominant gene. IV is not linked to either sex and is therefore called autosomal dominant. It may vary in its severity even in the same family and so IV is aid to show “variable penetrance” such that signs of the condition differ between generations and affected siblings.
What is the treatment?
Some people are so mildly affected that they do not use any treatment but most will benefit from applying moisturisers regularly, generally twice a day. There are a large number of effective moisturisers or emollients and each individual should try several in order to find the one or two that best suits them. Using a bath oil additive or emollient soap substitute is a useful way of mollifying the skin. As fine weather helps to improve IV these treatments may not be needed in summertime.