Aim of study: Few studies have evaluated the incidence of familial vesicoureteral reflux (VUR) among multiple gestation births. The purpose of this study was to determine the incidence and characteristics of VUR in twins in a large cohort of families with VUR.
Methods: Between 1998 and 2010, data were collected on 251 families (538 children) with at least 2 siblings who had VUR. The incidence of affected twins among the families was analysed. Data were assessed for age at presentation, gender, grading of VUR, laterality of affectation and renal scarring. VUR was diagnosed by voiding cystourethrography (VCUG) and dimercaptosuccinic acid (DMSA) scans were used to assess renal scarring.
Results: There were 12 families (4.8%) in which twins were affected with VUR. There were 12 index cases (7 males/5 females), and 12 siblings (1 male/11 females). All index cases presented with urinary tract infection (UTIs), whereas 2 siblings had UTIs and 10 were screened. All cases presented between 3 months and 2 years. Among the index cases, three had unilateral and nine had bilateral VUR. Among the siblings, four had unilateral and eight had bilateral VUR. Thirty-seven (90%) of the 41 affected renal refluxing units had high-grade VUR. Three index cases had renal scarring. No scarring was seen in the siblings.
Conclusions: The vast majority of twins with VUR are females who have high grade VUR and a low incidence of renal scarring. Twins with VUR may represent a genetically different subgroup with female preponderance and severe reflux.