Scientists from Aarhus University have for the first time identified gene variants that increase the risk of bedwetting (nocturnal enuresis) in children and young people.
It has long been thought that bedwetting might have an inherited pattern, as nocturnal enuresis is commonly seen in families, where it is common in kids if either parent had it. However, until now, this association has not been confirmed.
Now, with the use of a large-scale genome-wide association study (GWAS) in Denmark, a new study published in The Lancet Child & Adolescent Health reveals novel insights into how gene variants might increase the risks of bedwetting.
"As many as sixteen per cent of all seven-year-olds suffer from nocturnal enuresis and although many of them grow out of it, one to two per cent of all young adults still have this problem. It is a serious condition, which can negatively affect children's self-esteem and well-being. For example, the children may be afraid of being bullied, and often opt out of events that involve overnight stays," said Jane Hvarregaard Christensen, who was one of the scientists behind the study, in a statement.
The study assessed 3,882 children and young people that had a diagnosis of nocturnal enuresis or were currently on medication for it. The control group consisted of 31,073 children and young people that didn't have the condition, and the scientists could therefore compare the genomic differences between the two groups.
"We identified two locations in the genome where specific genetic variants increase the risk of bedwetting. The potential causal genes which we point to play roles in relation to ensuring that our brain develops the ability to keep urine production down at night, that the bladder's activity is regulated and registered, and that we sleep in an appropriate way, among other things," Cecilie Siggaard Jørgensen, first author of the study explained.
Additionally, the study also showed that those with nocturnal enuresis had common genetic variants found in everyone, with between 23.9 and 30.4% variance, explaining the genetic risk of up to one-third of bedwetting. However, it depends on how these common variants combine in an individual and other factors which ultimately result in bedwetting, not the variants alone if they are present.
"But you can still also have all the variants without wetting the bed at night, because there are other risk factors in play that we haven't mapped yet – both genetic and environmental. So it's clear that this is very complex and that it's not possible to talk about a single gene that causes nocturnal enuresis." Christensen explains.
Furthermore, the scientists also discovered that the same variants they identified that put individuals at risk for bedwetting are also commonly found in individuals with ADHD, hinting at a potential genetic link.
"Our findings don't mean that ADHD causes bedwetting in a child, or vice versa, but just that the two conditions have common genetic causes. More research in this area will be able to clarify the details in the biological differences and similarities between the two disorders," Christensen clarifies.
To make sure that the findings of the first-ever study on the genetic risk of bedwetting held true, and that it was not a coincidental discovery, the researchers also revealed they saw the same genetic variants in another GWAS group of 5,500 people they assessed in Iceland. They saw the same variants increased the risks of having nocturnal enuresis in the Icelandic group, suggesting a lower likelihood of it being coincidental.
"At present we still can't use a child's genetic profile to predict, for example, whether the child will grow out of its condition or whether a particular treatment works. Perhaps this will be possible in the future when more detailed studies have been conducted," Jane Hvarregaard Christensen concluded.