1999 Volume 65 Issue 6 Pages 297-310
The aim of this study was to clarify the genetic and environmental roles in nocturnal enuresis in childhood. The subjects aged 3 to 10 years were 916 twin pairs, consisting of 609 monozygotic (MZ), 272 dizygotic (DZ) and 35 unknown in zygosity. Covariance structure analysis was performed for the 881 twin pairs of known zygosity using program packages PRELIS2 and LISLEL8. The results demonstrated that (1) the prevalence of nocturnal enuresis was higher in males than in females for all ages, suggesting sex difference, (2) the concordance rates were higher in MZ than in DZ pairs for all ages, suggesting the existence of genetic factors, (3) directly, sex-limitation models, which estimate sex differences, fit in all cases, and heritability was higher in males for 3-4 years of age and in females for 5-8 years of age, implying importance of considering genetic factors for females whose enuresis continues, (4) the influence of environmental factors was estimated to be about 50%, supporting the effectiveness of an interventional approach for environmental factors. It is concluded that sex and age difference and genetic contribution should simultaneously be considered in the management of nocturnal enuresis in childhood.
