Study: genetics may cause balance disorders

BAR HARBOR – Researchers say a genetic defect that causes a severe immune deficiency in humans may also be to blame for certain balance disorders.

Research scientist David Bergstrom of the Jackson Laboratory in Bar Harbor said Monday that the findings, based on mouse studies at the Jackson Laboratory, the University of Iowa and East Carolina University, could guide future diagnosis and treatment of disorders related to balance and dizziness in humans.

Scientists examined a specialized strain of Jackson Lab mice that lacks production of a protein called p22phox. The absence of that protein causes the body to produce a faulty enzyme, leading to severe immune deficiency. Now researchers know it is also responsible for certain inner ear disorders as well, at least in mice.

Bergstrom said the enzyme can be likened to a multipurpose automotive tool – a wrench, for example, that can be used both to tighten a nut in the engine and to adjust the driver’s seat. The two operations are unrelated, but without the right wrench, neither can be accomplished.

In the lab mice, Bergstrom said, balance problems caused by the inner ear condition were evident, while researchers had to work to uncover the co-existing immunological condition caused by the same defective enzyme.

In humans affected by the defective enzyme, on the other hand, the inability to defend against infection is all too readily apparent.

“What we don’t know for sure, but suspect, is that they’re likely to have the balance problem as well,” Bergstrom said.

Bergstrom said that the research has already advanced understanding of the genetic basis of the two linked disorders and has implications for improving their diagnosis and treatment in humans.

The study was funded in part by grants from the National Institutes of Health and published online Friday in the Journal of Clinical Investigation.

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The Associated Press contributed to this story.