Scleroderma

Description

Alternative Names

Risk Factors

Scleroderma is uncommon and afflicts only about 150,000 Americans. The cause of scleroderma has not been determined and there are few specific risk factors. The incidence tends to be higher in certain groups, however.

Age. Systemic scleroderma usually develops between the ages of 35 and 55. Localized scleroderma is more common in children than adults, but is extremely rare even in the young age group. It occurs in between 0.2 and 0.4 per 100,000 people. Systemic scleroderma in children is even rarer.

Gender. The incidence of scleroderma is three to eight times higher in women than in men. Of possible importance was a 2002 study reporting that the disease tended to be less severe in women who developed it in middle age after being pregnant. Women who had an earlier onset and did not have a history of pregnancy had a much higher rate of complications. This may reflect a different cause of the disease in these two groups. (It should be noted that pregnancy itself is not a risk factor for scleroderma.)

Family History. A family history is the strongest risk factor for scleroderma, but even among family members, the risk is very low (less than 1%).

Genetics. Preliminary research suggests that patients with certain gene variations, or genetic polymorphisms, may be more susceptible to scleroderma than those who do not carry the polymorphism. For example, a 2004 study showed that the IL-1alpha-889 polymorphism is more common in patients with scleroderma than in healthy people.

Ethnicity. Limited data on risk by ethnic group suggests that the risk from highest to lowest is the following: Choctaw Native Americans (highest), African Americans, Hispanics, Caucasians, Japanese-Americans. African Americans have twice the rate of scleroderma as Caucasians.

African Americans also have a higher rate of diffuse scleroderma, lung involvement, and a worse prognosis than Caucasians. Other studies have also lower survival rates among Japanese Americans. A 2003 study further reported that even though African American with scleroderma tended to have more severe problems, they received poorer care than Caucasians patients at major medical centers.

Although economic factors certainly are involved in the disparities in severity among ethnic groups, genetic factors also may affect population groups differently. Studies are finding for instance, that ethnic groups differ in the incidence of specific antibodies. Caucasians for instance have a higher rate of anti-centromere antibodies, which are associated with limited disease, and African American patients have higher rates of autoantibodies and genetic factors that are associated with a more severe condition.

Geography. There appears to be certain geographic clusters of scleroderma or specific variants of scleroderma related to geography. This may suggest an infectious or genetic factor at work, but the reasons for this are largely unknown. The following are some examples:

• Studies reported significantly higher than average scleroderma mortality rates in male patients (both African American and white) who live in two specific regions of the Southeast: one cluster around Coffee, Tennessee and two others near Northampton, North Carolina.
• A cluster of scleroderma cases has been observed in South Boston, Massachusetts.
• There is a higher incidence of scleroderma cases among Choctaw Native Americans in Oklahoma. In the case of the Choctaw Native Americans, the incidence appears to have a strong genetic component. In most cases of geographic clusters, however, the disease is unlikely to be inherited and family members of patients are not at higher risk.