The similarity of mouse kidneys to human kidneys makes them extremely useful in scientific studies. For instance, researchers have gained a much better understanding of one of the most common forms of kidney disease by using genetically engineered mice as models for the disease. Affecting millions of people worldwide, IgA nephropathy, or Berger's disease, is a condition in which the kidneys cease to filter properly. The disease traditionally results in the need for dialysis or organ transplant. Thanks to researchers and their experimental mice, however, a far more convenient and safe option may soon be available.