A genetic discovery by researchers at Children’s and Brigham and Women’s Hospital brings new hope for a mysterious, devastating kidney disease called focal segmental glomerulosclerosis (FSGS). It’s the second leading cause of kidney failure in children and forces patients onto dialysis and, all too often, kidney transplant – only to recur in the transplanted kidney, sometimes within hours.
The research team, led by Elizabeth Brown, MD, of Children’s Division of Nephrology, performed a genetic linkage analysis in two large families with FSGS and identified a variety of mutations in a gene known as INF2. They then sequenced INF2 in 91 additional families. In all, they found INF2 mutations in 11 of 93 families, as reported online in Nature Genetics on December 20.
Other genes have been linked with FSGS, but Brown and colleagues think INF2 is an important find, as it seems to affect a larger number of families. The discovery may also shed some light on why the disease occurs.
INF2 encodes a protein that regulates actin, a protein vital to creating and maintaining the architecture of cells. Both actin and INF2 are abundant in podocytes, the kidney cells that are crucial in filtering toxins. The researchers thus believe the cause of FSGS may be disruption of podocytes’ structure and, therefore, function.
Right now treatments for FSGS are only guesses, because no one’s understood its underlying cause, says William Harmon, MD, chief of Children’s Division of Nephrology. Patients are mainly treated with steroids, which are only partially effective and have harsh side effects.
“FSGS is a frustrating disease for clinicians, as we have little understanding of the biology and poor treatment options,” says Brown. “We hope that further scientific work on INF2 will lead to better options.”
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