Introduction

In the present study enuresis is defined as repeated involuntary micturition after the fourth year of life, when not attributable to any gross organic lesion (cp. Chapter 4 ) . Enuresis is a rather frequent disorder in children, the morbidity risk in the general population being approximately 13 % among boys and 9 % among girls, of whom the great majority, about 90 %, suffer from nocturnal enuresis-cp. Hallgren (1956 a). It is not a serious disorder in the sense of disabling the affected individual physically. However, enuresis often causes great mental suffering to enuretic children and their parents. During the course of the years a large number of publications has appeared dealing with the aetiology and treatment of enuresis. As to the aetiology, the main interest has been directed towards the possible r61e played by various mental disturbances and by disorders of the urinary tract. The investigations indicate that urinary tract disorders are of minor importance as a direct cause of enuresis. On the other hand, a relationship obviously exists between enuresis and emotional disturbances. Since the problem has not been systematically studied in representative series, it is still a moot point to what extent the relationship may be causal. Comprehensive bibliographies are found in the papers by inter alia Zappert (1920), Anderson (19301, Rauchfuss (19391, Lechler (1949), and Hallgren (1956 b) . Several reports have been published describing enuresis occurring in different members of a single family. Some workers have interpreted these observations in genetic terms. Others have argued against such an interpretation, pointing out the possibility of unfavourable environmental factors being responsible for a familial occurrence. These divergent opinions may be explained by the fact that in the literature regarding enuresis, there are no unobjectionable genetic studies which also consider the possible influence of non-genetic factors. A survey of previous investigations of the familial occurrence and heredity of enuresis will be given in Chapter 1. The main purpose of the present study is to contribute, through a combined clinical and genetic analysis, to our knowledge of the aetiology of enuresis. The principal objects of the study are the following :