Ichthyosis Overview

Ichthyosis, pronounced Ick-thee-o-sis (which comes from the Greek word meaning ‘fish’) describes a group of conditions in which the skin is dry and scaly. Lots of people have dry skin conditions (such as eczema or psoriasis) but they tend to be patchy and they come and go. By contrast, in ichthyosis the scaling is continuous and usually affects the whole body. Most types are congenital, meaning that they are present at birth, and inherited, meaning that they result from genetic changes, so they may run in families. More information on this can be found in the ‘What is meant by congenital ichthyosis leaflet’.

There are many different types of ichthyosis. Some are listed in the table below. Please note that this is not an exhaustive list of all forms of ichthyosis and there are a number of other syndromes with ichthyosis. This information focuses on the forms of ichthyosis relevant to the majority of ichthyosis patients. Some of the rarer forms (or related syndromes) are dealt with in the ‘Rarer forms of ichthyosis’ leaflet. Leaflets about specific conditions can also be found on our website.

You are likely to have lots of questions and concerns about ichthyosis which you may wish to discuss with your doctor, but the following section may help to answer some questions which individuals and parents often ask.

The skin is made up of millions of tiny cells joined together to form our protective covering. Skin is a living organ which has to grow, adapt and respond to damage. It is constantly shedding (or exfoliating) and being replaced, and these processes are controlled by genes. Mistakes (‘mutations’) in genes cause malfunction. Ichthyosis is caused by mutations in genes that control the formation of skin cells, so they don’t function properly. Different types of ichthyosis are caused by mutations in different genes: in some, skin cells are formed at a faster rate than they are needed and they pile up on the skin surface, thickening the skin. In other forms, the cells are produced at the normal rate but instead of brushing off when they reach the surface, they cannot become detached from the cells beneath them and so they build up in layers. Either way, the end result is ichthyosis.

There is no cure for ichthyosis at present, but it is possible to manage the symptoms.

The main aim of treatment is to improve the condition of the skin (make it less dry and less scaly, for example) and to relieve discomfort. This is primarily achieved through regular, intensive (at least twice daily) use of moisturisers, sometimes with antiseptics or antibiotics, and occasionally with retinoids – a group of drugs that can reduce skin scaling – and other medicines as needed. Treatment is dealt with in more detail in the ‘Managing Ichthyosis leaflet’.

The congenital (inherited) forms of ichthyosis tend to persist throughout life, although the symptoms may become milder as time goes on. If you have a child with ichthyosis you may need to help them deal with people’s reaction to the appearance of ichthyosis, or if you have the condition yourself you may have experienced unhelpful reactions first hand – this can seem hostile and unsympathetic and while it often stems from ignorance, the effect on you or your child should not be underestimated. Two of the most difficult times are when a child starts school, and potentially has to deal with the staring and teasing on their own for the first time, and during the teenage years when it is so important not to be different from your peers. As an adult you may also experience diffi cult times when starting college, university, a new job or starting new relationships. The ISG has two leaflets – ‘Growing up with ichthyosis’ (for teenagers and young adults) and ‘What’s it like to have ichthyosis?’ (for younger children) to address some of these issues. There is also a leaflet that you can give to teachers, group leaders and others who may care for your child to help explain a bit about ichthyosis and the things that they need to watch for.

The ISG exists to help people like you and children with ichthyosis, by providing opportunities to meet other families and individuals with the condition to share experiences, and hints and tips for managing the condition. You may also find our leaflets on dealing with healthcare professionals and how to explain the condition to teachers, childminders etc useful.

Please contact the ISG for more information, advice, details on useful products, and to be connected with other people to share experiences and helpful advice.

Ichthyosis vulgaris

This is the commonest form of inherited ichthyosis, affecting 1 in every 250 people. Ichthyosis vulgaris has been found to be due to a gene defect in filaggrin, which is a protein in the skin that impairs the skin barrier formation and the natural moisturising factors that are key to keeping the skin hydrated. It is usually quite mild and develops in early childhood with fine, light grey scales and roughness on the upper and lower limbs, but sparing the folds of the arms and legs. It may be more widespread and is more obvious in the winter time. It is sometimes associated with atopic or childhood allergic eczema and may cause an increased wrinkling of the palms and soles.

It can be treated with regular application of moisturisers. It improves in adult life and may be passed on to children whereby there is a 50:50 chance of each child having the disease (“autosomal dominant transmission”).

X-linked ichthyosis

This condition occurs in males only and develops in infancy with tan or grey scales on the limbs and across the trunk. It may affect the ears and face and the scales appear to be stuck on like stamps. It varies in its severity and improves in fine or sunny weather. It changes very little with age.

X-linked ichthyosis is due to lower levels of an enzyme known as steroid sulphatase. This condition is passed on by a mother, who is a carrier of the abnormal gene, to her son with a 50% risk for each son. A carrier mother shows no evidence of the condition. The gene that causes this condition has been identified and, very rarely, a similar fault can affect adjacent genes on the same chromosome, causing a variety of other problems for an affected male, for instance, bony defects or lack of the sense of smell.

A mother who is carrying an affected male baby may have a prolonged and consequently difficult labour. A small number of affected boys have poorly descended or undescended testicles; it is usual to check this aspect of development in affected families. The child's growth should be monitored from time to time. It is quite common to have asymptomatic specks in the cornea that do not interfere with vision which are identified by an eye specialist.

Autosomal recessive congenital ichthyoses

There are three types of ichthyoses in this category: Congenital ichthyosiform erythroderma, Lamellar ichthyosis and Harlequin ichthyosis. These three conditions are passed on by parents with normal skin who both carry the abnormal gene (autosomal recessive) and the risk of a further child being affected is 1 in 4.

Congenital ichthyosiform erythroderma

This type of ichthyosis generally show signs at birth with the appearance of a collodion membrane on the newborn baby. This is a shiny yellow film stretched across the skin like a sausage skin. It dries out and gradually sheds within the first week of life. The "collodion baby" is nursed in a humidified incubator until the skin settles down. The majority of collodion babies will develop congenital ichthyosiform erythroderma. However, a small number of these babies will have normal skin once the membrane is shed and, therefore, it is not possible to accurately predict the outcome in the early stages.

Most collodion babies develop non-bullous ichthyosiform erythroderma, which literally means inflamed, scaly skin, without blisters. It affects 1 in every 300,000 births and so is very rare. Once the collodion membrane has shed, the skin remains red and has fine, white scales affecting the entire skin surface. In severely affected children the eyelids may be pulled outwards and there may be some mild scalp hair loss and tightness of the fingers. Because the skin is inflamed it will feel hot, even if the child is cold. Most children with this condition do not sweat normally and may overheat in hot weather, when exercising or with a fever. The palms and soles are sometimes thickened and scaly. Otherwise a child's health is normal. They may suffer cosmetically and this is especially important when a child starts school, or in the teenage years.

Lamellar ichthyosis

Lamellar ichthyosis is a rare form occurring in 1 in 200,000 live births. Newborns usually present with a collodian membrane but the skin is different in that it is less red but the scaling is larger, perhaps darker and more adherent, or stuck down.

Harlequin ichthyosis

Harlequin ichthyosis is a very severe, but extremely rare type of inherited ichthyosis (approximately 5 per year in the UK). It is evident at birth due to the very thick scaling all over. Intensive care is required and detailed information on the condition will be needed for the parents and staff.

Bullous ichthyosis

Bullous ichthyosis also known as bullous ichthyosiform erythroderma, is another rare inherited ichthyosis. At birth the baby's skin seems to be fragile and may show blisters, without much scaling. This causes severe problems for the young infant and intensive care is sometimes necessary in the first few weeks of life. A skin biopsy will be required early on to confirm the diagnosis. During the first year or two of life, the blistering tendency reduces but widespread redness, scaling and thickening of the skin becomes more obvious through childhood. This produces warty skin changes around the creases of the joints. Skin infections are quite common and can lead to a characteristic odour. There may be a reduction in sweating in childhood, which improves later in life. This is a troublesome and distressing condition for the child and the family.

It is transmitted as an autosomal dominant disorder, which means that one of the parents may be affected. However, in at least half of affected children, neither parent is affected; therefore the child has developed a new gene fault while growing in the womb. This means that there is no risk above the ordinary for further pregnancies in that family although the child may pass on the condition onto the next generation. Detailed genetic counselling is necessary.

Netherton's syndrome

The incidence of this condition is not known but it is probably in the region of 1 in each 200,000 births in the UK. The newborn child is very red and has scaly or peeling skin. The infant is often underweight and slow to grow and this problem continues for the first year or two of life. The affected child may need prolonged hospital treatment until both the skin and the nutrition improve. A characteristic feature of Netherton's syndrome is thin fragile scalp hair in the baby. Later it is spiky and this is an important clue to the diagnosis. In many affected children the skin improves in childhood, although it can flare up without warning.

Netherton's syndrome is an autosomal recessive disorder where both parents are carriers and show no sign of the condition. There is however a risk to further babies of the order of 25%.

There are a number of other genetic or inherited forms of ichthyosis where there are other medical problems but these are so uncommon that they are not discussed here.