Zellweger spectrum disorders are a group of rare, genetic, multisystem disorders that were once thought to be separate entities. These disorders are now classified as different expressions (variants) of one disease process. Collectively, they form a spectrum or continuum of disease. Zellweger syndrome is the most severe form; neonatal adrenoleukodystrophy is the intermediate form; and infantile Refsum disease is the mildest form. Zellweger spectrum disorders can affect most organs of the body. Neurological deficits, loss of muscle tone (hypotonia), hearing loss, vision problems, liver dysfunction, and kidney abnormalities are common findings. Zellweger spectrum disorders often result in severe, life-threatening complications early during infancy. Some individuals with milder forms have lived into adulthood. Zellweger spectrum disorders are inherited as autosomal recessive traits.

Zellweger spectrum disorders are also known as peroxisome biogenesis disorders (PBDs) - a group of disorders characterized by the failure of the body to produce peroxisomes that function properly. Peroxisomes are very small, membrane-bound structures within the gel-like fluid (cytoplasm) of cells that play a vital role in numerous biochemical processes in the body. PBDs are subdivided into the three Zellweger spectrum disorders and rhizomelic chondrodysplasia punctata.

Typically, Bowen disease appears as a slow-growing, persistent reddish-brown patch or plaque of dry, scaly skin. These lesions may be flat or slightly raised. The lesions are normally not associated with any symptoms, but, occasionally, can itch, ooze pus (if infected), bleed or become crusted and/or tender. In some cases, the lesions may be warty (verrucous), split open (fissured) or, less often, darkly colored (pigmented). In most cases, there is only one lesion, but in approximately 10-20 percent of individuals multiple lesions may develop usually in more than one area of the body.

Although Bowen disease occurs most often on sun exposed areas of the skin, it can develop anywhere on the body, even areas of the skin that are not usually exposed to the sun. The disorder most often develops on the lower legs. Less commonly, the head, neck, palms, soles and genitals can be affected. The lesions can measure anywhere from a few millimeters to a few centimeters.

Individuals with Bowen disease are at risk of developing skin cancer. The risk is estimated to be less than 10 percent, but can be higher in individuals with a compromised immune system. Early signs of cancerous transformation in Bowen disease include the development of a fleshy nodule or bump in a skin lesion. This nodule may be tender and bleed easily. Ulceration or hardening (induration) of a skin lesion also indicates malignant transformation.

Bowen disease is classified as an early, noninvasive form of squamous cell carcinoma, a type of skin cancer that most often occurs on sun damage areas of the skin. Squamous cell carcinoma is the second most common form of skin cancer.

Bowen-Conradi syndrome is caused by a mutation in the EMG1 gene. This gene provides instructions for making a protein that is involved in the production of cellular structures called ribosomes, which process the cell's genetic instructions to create new proteins. Ribosomes are assembled in a cell compartment called the nucleolus.

The particular EMG1 gene mutation known to cause Bowen-Conradi syndrome is thought to make the protein unstable, resulting in a decrease in the amount of EMG1 protein that is available in the nucleolus. A shortage of this protein in the nucleolus would impair ribosome production, which may reduce cell growth and division (proliferation); however, it is unknown how EMG1 gene mutations lead to the particular signs and symptoms of Bowen-Conradi syndrome.

Treatment of Bowen Hutterite Syndrome is symptomatic and supportive. Feeding through a surgical opening into the stomach (gastrostomy) may be needed in some cases.

Genetic counseling will be of benefit for patients and their families.

The exact incidence of Bowen disease in the general population is unknown. Bowen disease is most frequently diagnosed in Caucasian individuals over the age of 60, although can occur in individuals much younger. It is believed to occur more frequently in males than females.