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PBC risk increases among relatives of diagnosed patients

A population-based study in Iceland showed that first-, second- and third-degree relatives of patients with primary biliary cholangitis have a significantly increased risk for the disease.

“The results substantially extend previous observations on the familiality of PBC, by showing that an increased risk of disease extends significantly to both second- and third-degree relatives,” the researchers wrote. “This supports a strong role of genetics in the pathogenesis of PBC and provides a further rationale for utilizing genetic research methods to uncover novel genetic factors associated with development of the disease.”

The researchers accessed the Icelandic genealogical database and identified 222 patients diagnosed with PBC between 1991 and 2015. Median patient age was 62 years and 182 were women. Investigators also included 10,000 matched controls for each patient with PBC.

First-degree relatives of patients with PBC were significantly more likely to receive a diagnosis of PBC than the general population (RR = 9.13; 95% CI, 4.17-16.76). The estimated prevalence of the disease among this cohort was 37.3 per 10,000.

Second-degree relatives (RR = 3.61; 95% CI, 1.48-8.92) and third-degree relatives (RR = 2.59; 95% CI, 1.35-4.67) of patients with PBC also had significantly increased risks for diagnosis of the disease. The prevalence of PBC was 14.8 per 10,000 among second-degree relatives and 10.6 per 10,000 among third-degree relatives.

Although the results were not significant, the researchers observed an increased trend for diagnosis of PBC among fourth- and fifth-degree relatives of patients with PBC.

The relative risks were similar for both men and women at each degree of relation.

Patients with PBC were significantly more interrelated than the control subjects based on a kinship coefficient value (21.34 x 10^-5 vs. 9.56 x 10^-5; P < .0001).

“Contrary to many other liver diseases, strong associations between PBC and specific environmental factors have not been identified, although smoking, urinary tract infections, and hormonal factors have been reported to affect risk,” the researchers concluded. “Epigenetic changes have also been implicated in the pathogenesis of the disease. It therefore seems likely that an interplay between genetic and environmental components is necessary for the development of the disease.” – by Talitha Bennett

Disclosure: The authors report no relevant financial disclosures.