Familial risks in urolithiasis in the population of Sweden

Objective To assess detailed familial risks for medically diagnosed urolithiasis ( UL , urinary tract stone disease) based on nationwide hospital and population records. Patients/Subjects and Methods Subjects were identified from the Swedish Multigeneration Register in which there were 211 718 patients with UL . Standardised incidence ratios ( SIR s) were calculated by comparison to individuals without a family history of UL . Results The highest familial SIR s were invariably found for the same (concordant) type of UL : 2.18 for kidney, 2.20 for ureter, and 1.93 for bladder. SIR s increased from 1.84, when one parent was affected, to 3.54 when both parents were affected, which was a multiplicative interaction. The SIR was 1.79 when one sibling was affected but it increased to 24.91 when two siblings were affected. Such excessive risks (5.2% of familial cases) are probably explained by high‐penetrant genes. A low SIR of 1.29 between spouses suggested a minor contribution by shared environmental factors on the familial risk. Conclusions The results point to underlying genetic causes for the observed familial clustering and establish the genetic landscape of UL . Family histories should be taken in UL diagnostics and prevention could follow guidelines recommended for recurrent UL .