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Study: Risk for systemic sclerosis increases if a relative has the disease
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Study findings in Taiwan suggest the risk for systemic sclerosis increases if a relative has the disease.
“We found that the prevalence of [systemic sclerosis] SSc in relatives of patients with the disease is significantly higher than the general population and that the familial transmission of SSc was 0.72,” Chang-Fu Kuo, MD, PhD, in the Division of Rheumatology at Chang Gung Memorial Hospital in Taiwan, and colleagues wrote.
They added, “Our study provides several lines of evidence supporting the importance of familial factors, including both genes and environment, in the susceptibility of SSc.”
In the United States the prevalence of SSc is 24.2 per 100,000 adults. It is 5.6 per 100,000 in Taiwan, the researchers wrote. While researchers found an increased risk for SSc in those with a family history of lupus and Sjögren’s syndrome, this risk had not been previously studied in those with a family history of SSc.
To assess the risk in this patient group, Kuo and colleagues identified 23,658,577 beneficiaries of Taiwan National Health Insurance in 2010. Of these, 1,891 individuals had SSc. There were 21,009,551 parent-child relationships and 17,168,340 sibling-sibling pairs. Afterward, the researchers estimated the familial risks and transmission rate for SSc as well as the familial risks for other autoimmune diseases.
Researchers found the prevalence of SSc was 0.008%. There were 3,801 people with at least one first-degree relative with SSc, of whom 0.08% had the disease. Having a sibling with SSc was associated with an increased risk for the disease (relative risk = 81.21). Having a first-degree relative with SSc was associated with an increased risk for idiopathic inflammatory myositis (relative risk = 8.05), systemic lupus erythematosus (relative risk = 6.51), Sjögren’s syndrome (relative risk = 2.77), rheumatoid arthritis (adjusted relative risk = 2.64) and psoriasis (relative risk = 1.52). The familial transmission rate of SSc was 0.72. However, 84.1% of those with the disease were considered sporadic cases. In addition, family factors explained more than two-thirds of phenotypic variance of the disease, the researchers wrote.
They concluded these findings may be useful in advising families of patients with SSc.
“An unselective screening for SSc and other autoimmune diseases in all asymptomatic family members of patients with SSc is not recommended given a low absolute risk of these conditions,” the researchers wrote. “On the contrary, a positive family history is an important hint for those suspected of having an autoimmune disease.” – by Will Offit
Disclosure: The researchers report no relevant financial disclosures.
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