title: Familial Transmission of Hospital-Treated Varicose Veins in Adoptees: A Swedish Family Study.
abstract: Varicose veins (VVs) cluster in families, but the familial risk of VVs has not been determined among adoptees. The aim was to estimate whether the familial transmission of VVs is related to disease in biological and/or adoptive parents.
  
  
  
  The Swedish Multi-Generation Register and the Swedish Patient Register were used to follow all Swedish-born adoptees (born 1932 through 2004) that could be linked to both their biological and their adoptive parents (n = 80,214; 50% females). The risk of VVs was estimated in adoptees with at least 1 biological parent with VVs, but no adoptive parent with VVs (n = 187) compared with adoptees without a biological or adoptive parent with VVs (n = 1,758). The risk of VVs was also determined in adoptees with at least 1 adoptive parent, but no biological parent with VVs (n = 87), and in adoptees with both biological and adoptive parents affected (n = 21).
  
  
  
  Adoptees from an affected biological parent, but no adoptive parent, were more likely to have VVs than adoptees from an unaffected biological or adoptive parent (standard incidence ratio [SIR] = 2.21; 95% CI, 1.91-2.55). The familial SIR for adoptees with both an affected biological parent and an adoptive parent was 4.58 (95% CI, 2.83-7.01). Adoptees with an affected adoptive parent but no biological parent were not at increased risk of VVs (SIR = 1.15; 95% CI, 0.92-1.42).
  
  
  
  These novel findings suggest that genetic factors make a strong contribution to the familial transmission of VVs from parents to offspring, although familial environmental factors might contribute.
authors.affiliation: Department of Dermatology, Faculty of Medicine, Shimane University, Izumo, Japan; Center for Community-Based Health Research and Education (CoHRE), Organization for the Promotion of Project Research, Shimane University, Izumo, Japan. Electronic address: nine_kk@med.shimane-u.ac.jp.
authors.forename: Kunie
authors.initials: K
authors.lastname: Kohno
authors.affiliation: Department of Dermatology, Faculty of Medicine, Shimane University, Izumo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Niihara
authors.affiliation: Center for Primary Health Care Research, Lund University, Malmö, Sweden.
authors.forename: Xinjun
authors.initials: X
authors.lastname: Li
authors.affiliation: Center for Community-Based Health Research and Education (CoHRE), Organization for the Promotion of Project Research, Shimane University, Izumo, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Hamano
authors.affiliation: Center for Community-Based Health Research and Education (CoHRE), Organization for the Promotion of Project Research, Shimane University, Izumo, Japan; Department of Functional Pathology, Shimane University, Izumo, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Nabika
authors.affiliation: Department of Environmental and Preventive Medicine, Shimane University, Izumo, Japan.
authors.forename: Kuninori
authors.initials: K
authors.lastname: Shiwaku
authors.affiliation: Department of Functional Pathology, Shimane University, Izumo, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Isomura
authors.affiliation: Department of Dermatology, Faculty of Medicine, Shimane University, Izumo, Japan.
authors.forename: Eishin
authors.initials: E
authors.lastname: Morita
authors.affiliation: Center for Primary Health Care Research, Lund University, Malmö, Sweden; Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, CA.
authors.forename: Kristina
authors.initials: K
authors.lastname: Sundquist
authors.affiliation: Center for Primary Health Care Research, Lund University, Malmö, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Zöller
mesh_terms: D000300:Adoption; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010290:Parents; D012307:Risk Factors; D012959:Socioeconomic Factors; D013548:Sweden / Q000453:epidemiology; D014648:Varicose Veins / Q000453:epidemiology* / Q000235:genetics* / Q000628:therapy