PT  - JOURNAL ARTICLE
AU  - A Sverrild
AU  - V Backer
AU  - K O Kyvik
AU  - J Kaprio
AU  - N Milman
AU  - C B Svendsen
AU  - S F Thomsen
TI  - Heredity in sarcoidosis: a registry-based twin study
AID  - 10.1136/thx.2007.094060
DP  - 2008 Oct 01
TA  - Thorax
PG  - 894--896
VI  - 63
IP  - 10
4099  - http://thorax.bmj.com/content/63/10/894.short
4100  - http://thorax.bmj.com/content/63/10/894.full
SO  - Thorax2008 Oct 01; 63
AB  - Background: Sarcoidosis is a multiorgan granulomatous inflammatory disease of unknown aetiology. Familial clustering of cases and ethnic variation in the epidemiology suggests a genetic influence on susceptibility to the disease. This paper reports twin concordance and heritability estimates of sarcoidosis in order to assess the overall contribution of genetic factors to the disease susceptibility.Methods: Monozygotic and dizygotic twins enrolled in the Danish and the Finnish population-based national twin cohorts (61 662 pairs in total) were linked to diagnostic information on sarcoidosis obtained from the Danish National Patient Registry or the Social Insurance Institution, Finland registry of reimbursed medication using the 8th and 10th editions of the International Classification of Diseases. The Fisher exact test was used to compare probandwise concordance rates in different zygosity groups. Heritability was estimated based on a multifactorial threshold liability model.Results: A total of 210 twin pairs with at least one proband with a diagnosis of sarcoidosis were identified. The probandwise concordance rate was higher in monozygotic than in dizygotic twins (0.148 vs 0.012). Compared with the general population there was an 80-fold increased risk of developing sarcoidosis in co-twins of affected monozygotic brothers or sisters. The increased risk in dizygotic twins was only 7-fold. Aetiological model fitting gave a heritability of sarcoidosis of 0.66 (95% CI 0.45 to 0.80).Conclusions: This study suggests that genetic factors play an important role in the susceptibility to sarcoidosis. This result should encourage the search for molecular genetic markers of susceptibility to the disease.