This is the most common form of inherited ichthyosis, affecting 1 in every 250 births. Ichthyosis vulgaris is due to a gene change causing loss of function in a skin protein called filaggrin. This protein helps to form an effective barrier to protect the outer skin from irritants and prevent it from drying out. It also forms natural moisturising substances that are key to keeping the skin hydrated. Therefore, when the gene for this protein is altered, the skin barrier doesn’t work as well.  

Ichthyosis vulgaris is usually quite mild and develops in early childhood. It is characterised by fine, white to grey scales on the abdomen, arms and legs. The face, elbows, armpits and knee creases are usually unaffected. Rough bumps can appear on the skin of the arms and legs.  The palms and soles may have increased skin markings. It may be more widespread and obvious in the wintertime. It is sometimes associated with being atopic (overreactive immune system which causes asthma, allergies and eczema) and generally improves in adult life.  

This condition only affects males. It occurs in about 1 in 6000 births. It can cause generalised peeling of the skin in newborns and then fine scales on the trunk and limbs in infancy. Over time, the scales become thicker with a brown or grey colour. These thicker scales do not peel very easily and appear to be stuck on.  It mainly affects the lower legs, upper arms and abdomen. The elbow and knee creases are often not affected. It varies in its severity and generally improves in warmer weather and adult life.  

X-linked ichthyosis is due to lower levels of an enzyme known as steroid sulfatase.  This condition is only seen in people born as males. Females may carry the faulty gene. They can pass it on to a son with a 50% risk for each son. In very rare cases a carrier mother may show some mild symptoms of the condition.  

Most commonly, X-linked ichthyosis is caused when a part of the X chromosome which includes the steroid sulfatase gene is missing. Boys and men affected in this way may have other conditions such as autism, learning difficulties, abnormal heart rhythms or loss of smell. These can occur depending on what other genes are also “deleted” alongside the ichthyosis gene. In other cases, X-linked ichthyosis results from a mutation within the steroid sulfatase gene – this does not usually have associated problems. 

A mother who is carrying an affected male baby may have a prolonged and 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 painless spots on the surface of the eye (the cornea). These spots are called asymptomatic specks and do not interfere with vision. 

There are three main types of ichthyoses in this group: 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). The chance of each of their children being affected is 1 in 4. 

This type of ichthyosis generally shows signs at birth. The baby’s body will   be covered by a collodion membrane. This is a shiny yellow film stretched across the skin which 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 which is termed self-improving collodion ichthyosis.  

Congenital ichthyosiform erythroderma causes inflamed, scaly skin, without blisters. It affects 1 in every 200,000 births. Once the collodion membrane has shed, the skin remains red and has fine, white scales covering the entire body 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 affected by 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.  The child’s health is otherwise normal.  

Lamellar ichthyosis occurs in about 1 in 200,000 births. Newborns usually present with a collodion membrane. Once the membrane is shed in the skin is less inflamed, but the scales are larger and generally darker or brownish in colour. The scales can affect the whole body but may be larger on the legs. The skin on the palms and soles of the feet may be thickened with painful cracks. The skin loses more water causing dehydration and there is a risk of skin infection. 

The baby will be nursed in an incubator and have intensive care to cope with all the expected problems.  Some children are often admitted to hospital with repeated infections and dehydration. 

Some of the skin signs seen in congenital ichthyosiform erythroderma and lamellar ichthyosis can be similar. Alterations in many different genes can result in autosomal recessive congenital ichthyosis. Bathing suit ichthyosis is a rare form of autosomal recessive congenital ichthyosis. Newborns with this condition often have a collodion membrane. After the membrane is shed and over time, areas affected by large dark-coloured scales become limited to warmer parts of the body such as the scalp and body, rather than the arms and legs. 

Harlequin ichthyosis is an extremely rare and severe type of inherited ichthyosis (approximately 5 cases per year in the UK). It is evident at birth due to the very tight, thick scaling skin all over the body.  

Harlequin ichthyosis causes the skin to split and fluid to leak out of it. This leads to deep cracks, dehydration and thickening of the skin.  The thickened skin prevents the production of sweat. In turn, this leads to the body’s inability to regulate its temperature. The face looks stretched with turned out lips and eyelids; the ears, hands and feet may be hidden in the scale.  The eyes may be invisible because they are temporarily covered by the swollen eyelids. Feeding, and sometimes breathing, is difficult.  There is risk of serious infection.  

Immediately after birth, the baby will be nursed in the neonatal intensive care unit. They may need antibiotics to prevent skin infections.  They will be placed in an incubator and have intensive care to cope with all the expected problems. Skin creams and, in some cases, retinoid medicine will help the scale plates to shed in a few weeks.  Then the skin will appear red, tight and scaly all over and this is usually an ongoing problem.  

Parents will be taught how to cope with the day-to-day management. 

Epidermolytic ichthyosis 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 may be required early on to confirm the diagnosis. During the first year or two of life, the blistering tendency reduces but widespread redness/darkening, scaling and thickening of the skin becomes more obvious throughout childhood. This produces warty, ridged skin changes around the creases of the armpits, elbows and knees. Skin infections are quite common and can lead to a characteristic odour. Sweating may reduce during childhood and improve later in life. 

Epidermolytic ichthyosis is inherited 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 only a very small risk above the ordinary for the parents’ further pregnancies, although the affected child may pass the condition onto their children. Detailed genetic counselling is necessary. 

This is a condition where ichthyosis is associated with significant abnormalities elsewhere in the body.  

The incidence of this condition is not known but it is probably in the region of 1 in 100-200,000 births in the UK.  

The newborn child has very red/darker skin which can be scaly or peeling. The infant is often underweight and slow to grow (sometimes called failure to thrive). This problem continues for the first year or two of life. The affected child may need prolonged hospital treatment until both the skin and their nutrition improve. A characteristic feature of Netherton syndrome is thin fragile scalp hair in the baby. Later on, the hair becomes 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. Many patients are prone to develop food allergies. 

Netherton syndrome is an autosomal recessive disorder where both parents are carriers but show no signs of the condition. There is however a 1 in 4 risk for these parents of their children being affected.  

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