Some types of nephrotic syndrome can be treated with steroids or other drugs, but steroid-resistant forms of the disease as a rule do not respond to treatment. Untreated nephrotic syndrome often causes severe scarring and a condition called focal segmental glomerulosclerosis (FSGS), which progresses about 50 percent of the time to end-stage kidney disease and renal failure.
PLCE1 is the seventh gene scientists have found to be involved in different types of steroid-resistant nephrotic syndrome, and the second gene that is expressed in podocytes ?specialized cells with octopus-like tentacles surrounding the glomerulus.
Podocytes are currently under intensive study, because scientists believe they play a vital role in the blood filtration process. Identifying genes and proteins that are active in podocytes will help scientists understand how they work.
"We found that PLCE1 is expressed in developing and mature podocytes," says Hildebrandt. "Most of the PLCE1 mutations we identified apparently prevented podocytes from developing normally in the embryo, so defects were present at birth. A milder mutation seemed to interfere with repair mechanisms in the glomerulus, so defects didn't show up until later in life."
U-M scientists used DNA microarrays to analyze blood samples from 26 families around the world who had children diagnosed with steroid-resistant nephrotic syndrome. After eliminating known mutations, the study team was left with DNA from 12 children with the disease. All 12 had inherited recessive mutations in PLCE1 from both parents. None of the seven different PLCE1 mutations were present in the 138 control subjects in the study.
All 12 children developed symptoms of nephrotic syndrome before age four. Five children progressed to end-stage re
Source:University of Michigan Health System