Hereditary phenotypes in nocturnal enuresis

To identify phenotypic characteristics in three large families with autosomal dominant nocturnal enuresis (NE), and to elucidate whether such characteristics persist after cessation of symptoms.

From three unrelated NE kindreds (A-C) we included 98 living members of whom 34 either had active NE (>one wet night/month after the age of 5 years) or a history of NE. The family members were interviewed to identify NE type and severity. Subsequently, night-time urine production was recorded for 2 weeks at home and 4 days of frequency-volume charts were completed.

There was coexistence of both primary and secondary NE (family A), coexistence of monosymptomatic NE and incontinence (families A and C), pure monosymptomatic NE (family B) and pure day-time incontinence (family C). However, the NE phenotype of family A was characterized by nocturnal polyuria and normal bladder capacity, whereas family C was characterized by normal nocturnal urine production and reduced bladder capacity. Interestingly, there were no differences between former affected and unaffected family members in any of the families for night-time urine production, nocturia frequency, nocturia volumes, day-to-night ratios, or bladder capacity.

The clinical phenotype in three large families with hereditary severe NE was heterogeneous within and between families. However, the NE phenotype seemed to differ between two of the families for nocturnal urine production, bladder capacity, and response to desmopressin. These results indicate that the genes responsible for NE in these families are not related directly to the presence of primary vs secondary NE or coexisting day-time problems. However, there might be genetically determined differences in bladder capacity and/or nocturnal urine production.