Enuresis, Nocturnal, 1

Description

Nocturnal enuresis, or nightly bedwetting in children more than 7 years of age, affects about 10% of 7-year-old children, with a wide range of frequencies between populations. The affliction is often linked to major social maladjustments and occupies considerable time in general medical practice. From the age of 7, there is a spontaneous cure rate of 15% per year, such that few remain affected after the age of 16 years. There are 2 types of nocturnal enuresis: type I, the primary form (PNE), with at least 3 nightly episodes in children older than 7 years, where the child has always had the disorder, and type II, or secondary type, where the child has been dry for at least 6 months but enuresis has recurred (summary by Eiberg et al., 1995).

Genetic Heterogeneity of Nocturnal Enuresis

ENUR1 has been mapped to chromosome 13q, and ENUR2 has been mapped to chromosome 12q.

Inheritance

Eiberg et al. (1995) identified 17 families with nocturnal enuresis. In 11 of these families, type I nocturnal enuresis appeared to follow an autosomal dominant mode of inheritance with penetrance above 90%.

Muller (1997) observed a pair of 8-year-old monozygotic twins, only one of which suffered from nocturnal enuresis. The father, uncle, and grandfather of the twins also had nocturnal enuresis.

In a Swedish multicenter study, Arnell et al. (1997) ascertained 392 children with PNE and studied the inheritance pattern of the disorder in their families. Compatible with dominant inheritance, 168 (43%) of the children had an affected parent; 37 (9.4%) had an affected sib, taken to indicate autosomal recessive inheritance. The possibility of dominant inheritance with reduced penetrance was acknowledged. In 57 cases a more distant relative with PNE was found, and in 130 cases no family history of PNE was found.

Mapping

Eiberg et al. (1995) presented strong evidence of linkage of nocturnal enuresis with the DNA markers D13S291 (lod = 3.55 at theta = 0.07) and D13S263 (lod = 2.67 at theta = 0.08). Multipoint analysis indicated that these markers flanked the disease locus at 13q13-q14.3.

Arnell et al. (1997) studied sixteen 2- and 3-generation Swedish families showing a dominant pattern of inheritance of PNE. Suggestive linkage to the interval between D13S263 and D13S291 (Zmax = 2.1) was found in 3 families. Linkage to this region was excluded in 11 families. A positive 2-point lod score (Zmax = 4.2) was found in 6 families for D12S80 at theta = 0.05 (see 600808).