2 New Mutations Appear to Trigger aHUS in Woman After Kidney Transplant

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by Patricia Inacio PhD |

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Two newly reported mutations in a complement-related gene appear to have triggered atypical hemolytic uremic syndrome (aHUS) in a woman within months of a kidney transplant, according to a case report.

The report, “A novel Atypical hemolytic uremic Syndrome–Associated CFH gene in a renal transplant recipient complicated with ileum perforation,” was published as a letter to the editor in the Asian Journal of Surgery.

aHUS is characterized by the abnormal activity of the complement system, part of the body’s immune system. It belongs to a larger group of disorders called thrombotic microangiopathies (TMAs), which are characterized by the formation of blood clots in small blood vessels, leading to organ damage.

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While genetic factors alone do not cause aHUS, mutations in certain complement-associated genes, such as the CFH gene, can increase the risk of aHUS. The kidneys are commonly affected, often leading to kidney failure and the need for a transplant.

A 37-year-old woman in Taiwan with a history of kidney disease developed TMA within five months of undergoing a kidney transplant. Her TMA was complicated by a perforation of the ileum, the final and longest segment of the small intestine.

The woman was hospitalized with fever, vomiting, abdominal pain, tiredness, and graft problems with her transplanted kidney.

Clinical examination found destruction of red blood cells. But levels of an enzyme involved in blood clotting, called ADAMTS13, were normal, leading physicians to discard thrombotic thrombocytopenic purpura, another TMA, as a possible diagnosis.

She received plasma exchange therapy and, after four sessions, improved: her lab tests stabilized and the kidney transplant was salvaged.

One month later, a high fever and abdominal pain returned. An examination found the perforated ileum and she underwent an end-ileostomy, an abdominal surgery to remove that part of the intestine.

Analysis of the ileum tissue showed signs of scarring over small blood vessels, consistent with a TMA diagnosis. An analysis of the 22 genes associated with aHUS followed, revealing the presence of two newly reported mutations in the CFH gene.

No further episodes of the disease were noted in subsequent examinations, and the patient had no need for dialysis.

“Our experience suggests that these novel genomic aberrations affecting the genes encoding compliment factor H (CFH) is associated with post-transplant hemolytic-uremic syndrome,” the scientists wrote.

“The incidence of post-transplant de novo aHUS is likely underestimated, because the tissue diagnosis and confirmatory genetic results are usually not available at the time of presentation,” they noted.