Eczema (atopic Dermatitis): Genetic and Environmental Skin Condition

"Eczema affects about 10-20% of the world's population. 65% develop atopic dermatitis during their first year of life and 90% develop the condition by age 5" (Atopic Dermatitis, 2010). "According to the National Institute of Health and other investigations, approximately 10% of the U.S. population had, has or will have eczema of one form or another. No one, regardless of age, health, gender, or lifestyle, is immune to eczema" (Eczema, 2009). Yet most people do not even know what eczema is. Simply said it is a skin problem. Eczema is used as a general term for many types of skin inflammations and allergic rashes. "There are a couple of different types of eczema, such as contact, nummular (round or oval-shaped itchy lesions), irritant, allergic, and genetic eczema" (Alai, 2008). Since eczema is a general term it creates some confusion as it is used interchangeably with all the different types. The most prevalent type of eczema is genetic, also called atopic dermatitis. "Atopic" refers to a disease that is linked to genes and runs in families and "dermatitis" means inflammation of the skin.

Atopic dermatitis is a chronic skin disease that affects a large portion of the world's population. It is comprised of three conditions including asthma, allergies (hay fever), and eczema. The trademark of this disease includes skin rashes and itching. "The skin becomes extremely itchy and inflamed, causing redness, swelling, cracking, weeping, crusting, and scaling. Dry skin is a very common complaint and an underlying cause of some of the typical rash symptoms" (Alai, 2008).

Atopic dermatitis can occur at any time, but it mostly affects infants and young children. In some cases, it may continue on into adolescence and even adulthood. For these patients who suffer with atopic dermatitis well after infancy, it is highly likely that they will go through ups and downs for the rest of their lives. "In these cases, there are periods of time when the disease is worse, called exacerbations or flares, which are followed by periods when the skin improves or clears up entirely, called remissions" (Alai, 2008). For those that enter into a state of permanent remission from the disease, when they get older, may still complain about dry and easily irritated skin because there is an increased tendency to hypersensitivity.

An important factor of atopic dermatitis is the itchy sensation, because in response to this feeling, one starts to rub and scratch which makes the inflammation of the skin worse. The hypersensitivity that comes along with atopic dermatitis causes the patient to feel like they must scratch longer. "They develop what is referred to as the "itch-scratch" cycle. The extreme itchiness of the skin causes the person to scratch, which in turn worsens the itch, and so on." (Alai, 2008) The itching sensation seems to be worse when one is asleep because "conscious control of scratching decreases and the absence of other outside stimuli makes the itchiness more noticeable."(Alai, 2008) Intense sessions of scratching and rubbing result in lichenification which is the development of thick leatherPy skin. Others develop papules, or small raised bumps on the skin and when one scratches these bumps, they open and become infected.

Before the research done in 2006, the cause of atopic dermatitis was unknown. There was only conjecture that it was linked to a combination of genetic and environmental factors. There was evidence to suggest that the disease was associated with other atopic diseases such as hay fever and asthma. It also seemed that those that outgrew the symptoms of atopic dermatitis went on to develop either hay fever and/or asthma. While one may not necessarily cause another, since the evidence seemed to point to them being related, it gave researchers clues to understanding atopic dermatitis.

In 2006, experts lead by the University of Dundee in Scotland, discovered a gene which

"caused the genetic skin conditions affecting millions of people. [Collaborating] with other experts on genetic skin disorders in Dublin, Glasgow, Seattle and Copenhagen, they discovered the gene that causes dry, scaly skin and predisposes individuals to atopic dermatitis" (MediLexicon International Ltd., 2006).

Up until this point, only symptomatic treatment of the skin condition was possible by using topical steroids, "corticosteroid creams and ointments, antihistamines, or antibiotics and in more severe cases, systemic corticosteroid treatments or phototherapy, the use of ultraviolet (UV) light" (Frisch, 2010) to aid in the prevention of the skin from drying out and the reduction of inflamed skin . However, "now that the underlying gene defect behind this disorder is known, it [is] possible to design new more effective therapies to tackle the root cause of the problem, rather than treating the symptoms." (MediLexicon International Ltd., 2006)

The gene that they discovered "produces a protein called filaggrin which is normally found in large quantities in the outermost layers of the skin. This protein is essential for skin barrier function, helping to form a protective layer at the surface of the skin that keeps water in and keeps foreign organisms out" (MediLexicon International Ltd., 2006). The absence or decrease of this protein leads to the impaired formation of the skin barrier. This results in the skin drying out and causes poorly formed outer layers of skin that constantly flake off. The skin barrier is supposed to keep foreign substances out, however since the filaggrin mutations do not allow for a properly formed skin barrier, foreign substances get in and the immune system fights them off causing inflamed skin; one of the hallmarks of eczema.

A study done by geneticists Professor Irwin McLean and Dr Frances Smith in Dundee, found that in the United Kingdom "about 5 million people...carry one of the