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Autoimmune hepatitis risk low among first-degree relatives

Results from a large Danish-population study showed that first-degree relatives of patients with autoimmune hepatitis had an increased risk for the disease, although the risk was very low.

“Numerous genetic risk factors for [autoimmune hepatitis (AIH)] have been suggested, but genome-wide association studies indicate that genetics plays only a minor role,” Lisbet Grønbæk, MD, from the Aarhus University Hospital in Denmark, and colleagues wrote. “Our study demonstrates that AIH family accumulation is very uncommon, but at the same time indicates that genetic susceptibility does play a role in the complex etiology of AIH.”

Grønbæk and colleagues conducted a nationwide population-based study to determine the cumulative risk for AIH in first- and second-degree relatives of patients from patient’s index diagnosis. The study comprised 8,582 first-degree relatives and 9,230 second-degree relatives of 2,458 patients.

The researchers observed six incident cases of AIH, all among first-degree parent-child relatives, during 64,020 years of follow-up. The standardized incidence ratio was 4.9 (95% CI, 1.8-10.7) and the 10-year cumulative risk for AIH from patient index date was 0.1% (95% CI, 0.04-0.23).

No second-degree relatives developed AIH during the study period.

The study also included a subgroup of 64 twin pairs diagnosed with AIH. Among the twins, the researchers observed one incident of AIH between a monozygotic twin pair for a standardized incidence ratio in all twin pairs of 53.9 (95% CI, 1.5-300.4).

“This nationwide family and twin cohort study showed that the incidence of AIH in first-degree relatives of patients with AIH was fivefold increased,” the researchers wrote. “Our study supports the existence of familial clustering of AIH, but the absolute risk is very low.” – by Talitha Bennett

Disclosure: The authors report no relevant financial disclosures.