Study Finds Evidence That Bed-Wetting Is Hereditary
Researchers are close to isolating a defective gene responsible for a childhood problem that aggravates parents and embarrasses children--bed-wetting.
An estimated 5 million to 7 million American children over the age of 6 wet their beds at least once a week, and some researchers believe more than half of those cases are genetic in origin rather than psychological.
A team from the Danish Centre for Genome Research in Copenhagen reports today in the journal Nature Genetics that a study of 11 families with a history of the disorder has allowed them to localize the gene to a small segment on chromosome 13, one of the 23 pairs of chromosomes that make up the human genetic blueprint.
Although there may be as many as 10 genes in the segment, one--a brain chemical receptor called HTR-2--appears to be a good candidate as the cause of bed-wetting, according to biochemist Hans Eiberg, who led the team.
The localization will provide a genetic test for bed-wetting that could be valuable in treating the disorder: Preliminary evidence suggests that children whose bed-wetting is genetic in origin are the most responsive to drugs designed to halt the problem.
The discovery should also provide reassurance to parents who fear that the bed-wetting results from their own child-rearing practices, from emotional trauma in their children or from simple rebellion.
“A child who wets the bed does not do so on purpose,” Eiberg said. “Many cases of bed-wetting are caused by genetic factors beyond a child’s and parent’s control.”
The discovery was unexpected by many pediatricians. “It comes as a surprise to many because . . . there are so many different things that can cause [bed-wetting],” said Dr. Paul Horowitz of Childrens Hospital Los Angeles.
“While we suspected [bed-wetting] was hereditary, this is the first time a direct genetic link has been identified,” said Dr. Marc Cendron of the Dartmouth-Hitchcock Medical Center in New Hampshire. “This is a significant development in the evaluation and treatment of a condition that affects many children.”
It is significant, he added, because “bed-wetting has been swept under the carpet for a long while. People felt it was not a big deal, but we still see a lot of patients who have significant emotional problems because of it. Now we have something we can hang our hat on . . . that it has a biological basis, not a behavioral one.”
Bed-wetting, formally called enuresis, is common in very young children and is not considered a problem until about the age of 7. An estimated 8% of 7-year-olds suffer from enuresis, which comes in two forms, primary and secondary.
Primary enuresis, about 75% of cases, affects children who have never had a significant period of being dry at night. Secondary enuresis, the remaining 25%, describes those children who have been dry for at least six months and then revert to wetting the bed.
Researchers now believe that most cases of primary enuresis are genetic in origin, while secondary enuresis is caused by emotional trauma--such as the first day of school, birth of a sibling or a family dispute--or a medical problem, such as a bladder infection.
Many physicians tell parents to do nothing and allow the child to grow out of it. But that is a mistake, many experts now say, because only about 15% of bed-wetters recover spontaneously each year. “Treating bed-wetting can improve a child’s confidence and self-esteem,” said Dr. William Cromie of the University of Chicago. “There are safe and effective treatments available.”
Eiberg and his colleagues studied families in which many of the children were bed-wetters. In one such family, seven of 11 children suffered the problem. The team discovered a particular set of genetic markers that localized the problem to a small area of chromosome 13, and they are now looking for the specific gene.
