The gene is the second to be linked to the rare and potentially fatal disease, called urofacial syndrome (UFS), and both genes were identified by scientists at the University of Manchester's Centre for Genetic Medicine.
'We estimate that around 80 percent of all cases of UFS are attributable to one of the two genes that we've now identified', Dr Bill Newman, the leader of both studies, comments.
UFS is typified by two apparently incongruous characteristics. The first of these is a malfunctioning bladder which fails to fully expel urine, sending it back to the kidneys and damaging them. The second is a grimacing facial expression when smiling or laughing. UFS affects less than one in a million people worldwide.
In 2010, working with scientists in other international centres, Dr Newman's team pinpointed mutations in the HPSE2 gene as the cause of the syndrome in six families. In the current study, the researchers performed DNA analysis on a further three families - two Turkish and one Spanish - and identified mutations in the LRIG2 gene as being behind the condition in those cases.
The paper notes that there were 'no consistent clinical differences' between patients with changes in the LRIG2 or HPSE2 genes. Dr Newman says that future work will investigate the function of the LRIG2 gene. However, initial studies indicate that both genes are important in nerve development in the bladder.
With both genes involved in such an important biological pathway it seems likely they may be implicated in other conditions and Dr Newman's team are investigating this. Of particular interest are the estimated one percent of children who suffer from vesicoureteral reflux (VUR), when urine flows back toward the kidneys from the bladder.
'The appearance and behaviour of the bladder in VUR shows some similarities to what you see in UFS', says Dr Newman. 'We have already shown that changes in LRIG2 are present in some cases of unexplained bladder and reflux dysfunction. So UFS might be one of these rare conditions that gives us insight into a much more common health problem'.
Knowledge of the genes responsible in bladder dysfunction would in turn help with earlier diagnosis and could prevent kidney damage occurring. There may even be an impact on the kind of drug therapy used in those cases.
'Heparanase inhibitors are drugs that act in a similar way to the HSPE2 gene and have been studied in cancer treatment,' Dr Newman explains. 'If it turns out that HSPE2 is implicated in VUR then these drugs may be useful there. We're already looking at looking doing some studies to see if this could be the case'.
The study is published in the American Journal of Human Genetics and is a National Institute for Health Research Clinical Research Network portfolio study.