Background/Aims: The heritability of end-stage renal disease (ESRD) among adoptees has not been examined so far. By studying adoptees and their biological and adoptive parents, it is possible to differentiate between the genetic causes and environmental causes of familial aggregation. This nationwide study aimed to disentangle the genetic and shared environmental contribution to the familial transmission of ESRD. Methods: We performed a family study for Swedish-born adoptees (born between 1945 until 1995) and their biological and adoptive parents. The Swedish Multi-Generation Register was linked to the National Patient Registry for the period 1964–2012. ESRD was defined as patients in active uremic care, that is, chronic dialysis or kidney transplantation. OR for ESRD was determined for adoptees with an affected biological parent with ESRD compared with adoptees without a biological parent with ESRD. The OR for ESRD was also calculated in adoptees with an adoptive parent with ESRD compared with adoptees with an adoptive parent without ESRD. Moreover, heritability for ESRD was estimated with Falconer’s regression. Results: A total of 111 adoptees, 463 adoptive parents, and 397 biological parents were affected by ESRD. The OR for ESRD was 6.41 in adoptees (95% CI 2.96–13.89) of biological parents diagnosed with ESRD. The OR for ESRD was 2.40 in adoptees (95% CI 0.76–7.60) of adoptive parents diagnosed with ESRD. The heritability of ESRD was 59.5 ± 18.2%. Conclusion: The family history of ESRD in a biological parent is an important risk factor for ESRD. The high heritability indicates that genetic factors play an important role in understanding the etiology of ESRD.

Background/Aims: The heritability of end-stage renal disease (ESRD) among adoptees has not been examined so far. By studying adoptees and their biological and adoptive parents, it is possible to differentiate between the genetic causes and environmental causes of familial aggregation. This nationwide study aimed to disentangle the genetic and shared environmental contribution to the familial transmission of ESRD. Methods: We performed a family study for Swedish-born adoptees (born between 1945 until 1995) and their biological and adoptive parents. The Swedish Multi-Generation Register was linked to the National Patient Registry for the period 1964–2012. ESRD was defined as patients in active uremic care, that is, chronic dialysis or kidney transplantation. OR for ESRD was determined for adoptees with an affected biological parent with ESRD compared with adoptees without a biological parent with ESRD. The OR for ESRD was also calculated in adoptees with an adoptive parent with ESRD compared with adoptees with an adoptive parent without ESRD. Moreover, heritability for ESRD was estimated with Falconer’s regression. Results: A total of 111 adoptees, 463 adoptive parents, and 397 biological parents were affected by ESRD. The OR for ESRD was 6.41 in adoptees (95% CI 2.96–13.89) of biological parents diagnosed with ESRD. The OR for ESRD was 2.40 in adoptees (95% CI 0.76–7.60) of adoptive parents diagnosed with ESRD. The heritability of ESRD was 59.5 ± 18.2%. Conclusion: The family history of ESRD in a biological parent is an important risk factor for ESRD. The high heritability indicates that genetic factors play an important role in understanding the etiology of ESRD.