It is one of the most challenging congenital kidney conditions pediatric nephrologists see. Called congenital nephrotic syndrome (CNS), it is an extremely rare genetic disease that affects the glomerular filtration system of the kidneys, leading to tremendous loss of protein through the urine. The result is extensive edema, skin breakdown and impaired respiration.
And that’s just the beginning, said Daniel Feig, M.D., Ph.D., the Margaret M. Porter Endowed Chair in Pediatric Nephology at Children’s of Alabama and the University of Alabama at Birmingham (UAB).“These kids are very susceptible to infections because so many immune chemicals are lost in the urine,” he said. They are also prone to blood clots because of low water volume and poor circulation, which can severely damage other organs, leading to bowel infarction and stroke. “They also become very malnourished because they can’t take in enough protein to keep up with the losses through the urine,” he said.
Symptoms usually appear by 2 months of age. “But because this is a structural problem in the kidney filters, there is no medicine that stops it,” he said. Early management involves trying to replace lost protein, “but that’s usually not enough.” Second-line management includes medications to slow kidney function, “but now we’re walking a tightrope of impaired kidney function to reduce protein losses.”
Eventually, the kidneys need to be removed so the child can receive enough nourishment. That means dialysis until they can receive a transplant.
“They’re a challenge,” he said. “But over the years, we’ve had very good success in moving down the pathway and getting them transplanted and they do well.” Because the condition is so rare, most pediatric nephrologists only see one or two patients their entire career. But word of Children’s program has spread, and today the team is treating patients from throughout the south.
“As a program we are happy to take care of these kids and share our expertise with other programs,” Feig said. One challenge has been reimbursement since health insurance may not cover out-of-state care. “We’re negotiating with other states and our own internal services to accept what we can get and then just take care of the kids, he said, adding, “A big shout out to the flexibility of the institution to allow us to do this.”
The goal is to build a center of excellence for children with CNS that demonstrates not only superior outcomes, he said, but cost savings.
Becoming a referral center also allows greater clinical research into the disease, Feig said. Clinical trials for new therapies are difficult to conduct because there are so few children with the disease. But Children’s is slowly building a repository of biometric information and tissue for future research. “We don’t have a faculty researcher right now who is focused on CNS, but as we continue to recruit faculty that’s an untapped opportunity.” All the challenges of caring for these kids, he said, is worth it once they get a transplant. “They grow and develop and play just like all other small children. It’s a boon to these families who go through this terrible neonatal course and then get their kids back.”