X-Linked Ichthyosis only affects boys / men. The heredity depends on gender. Women can carry and pass on the gene but will not suffer from the skin problems. The condition affects approximately 1 in 2000-6000 men.
X-Linked Ichthyosis is caused by a genetic change on the X chromosome: the male gene. The X- and Y-chromosome determinate the male gender. Females have two X-chromosomes. So female carriers have one defect chromosome one healthy chromosome that compensates. For males this is not the case. The condition is caused by the STS gene that produces less of the enzyme called steroid sulphatase. STS regulates the chemical changes that allow dead skin to be shed from the body. When this enzyme is lacking, the dead skin cells build up as brown scales. The epidermis is thickened. It is important to know that the enzyme sulphatase plays a role in the induction of labour. Female carriers should inform their gynaecologist about this. The daughter of the female carrier has 50% chance to become carrier herself. The son of the carrier has 50% changes to be affected by the condition.
In the first weeks after birth the skin appears red with large transparent scales. The transparent scales make place for dark brown scales. They look to be attached to the skin as ‘fish scales’ with angular large shape. The torso, neck, arms and legs are affected. Even so are the skin creases like the knee or elbow. During summertime or in more humid climates the skin can have a better outlook.
Sometimes patients have visibility problems because the cornea of the eyes can be affected. Sometimes the testicles are not lowered properly. Sometimes there is a defect in the genes surrounding the STS gene causing other abnormalities to occur.
Skincare is important. Soap and water can dry the skin. Daily application of fatty cream is necessary. Cream with urea can be used against thick skin. More severe cases can be treated with acitretin. The skin condition does not improve with age.