Medical Health Encyclopedia

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.

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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.