aHUS Found in Boy With Rare, Severe Immune Deficiency Disorder

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by Patricia Inacio PhD |

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Atypical hemolytic uremic syndrome (aHUS) can co-exist with severe combined immunodeficiency (SCID), a rare genetic disorder characterized by a weakened immune system, a case report noted.

Prompt diagnosis is crucial to improving patient outcomes, its researchers wrote, especially as the two diseases “are considered to exacerbate each other.”

The report, “Atypical Hemolytic Uremic Syndrome (aHUS) andAdenosine Deaminase (ADA)-Deficient Severe Combined Immunodeficiency (SCID)—Two Diseases That Exacerbate Each Other: Case Report,” was published in the International Journal of Molecular Sciences.

aHUS and SCID are rare genetic disorders that can become life-threatening. Researchers in Poland described the case of a young boy with both conditions.

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At 9 months old, the boy came to their hospital with anuria — a condition in which the kidneys stop producing urine — accompanied by acute kidney injury, generalized swelling, and respiratory failure. The baby was admitted to the intensive care unit.

He had a clinical history of recurrent diarrhea from early infancy, low weight for his age, and potential delayed development. When he was 3 months old he had chickenpox (varicella), and at 9 months he also had herpes zoster infection (shingles).

Blood tests revealed signs of aHUS. The infant had high levels of reticulocytes (immature red blood cells), as well as high levels of bilirubin and creatinine, and increased lactate dehydrogenase (LDH) activity. His urine also had proteins and blood.

Peritoneal dialysis — given when kidneys fail to properly remove waste products from the blood — and blood transfusions were started due to aHUS being suspected.

Additional lab tests excluded other infections and thrombotic thrombocytopenic purpura (TTP), a rare disorder that can manifest in ways similar to aHUS.

Peritoneal dialysis continued for 29 days. However, the treatment, together with blood transfusions and medications, led to no significant improvements.

The boy was then given eight cycles of plasma exchange (plasmapheresis), a procedure that involves replacing plasma, the liquid part of blood, and he responded favorably. Soliris (eculizumab), an approved aHUS treatment, was not available to his doctors at the time, the report noted.

Multiple blood pressure medications were also prescribed, and the boy was released from the hospital and followed as an outpatient by the nephrology department.

“The obligatory combination of factors for aHUS to develop is believed to include infections, genetic disorders, and environmental susceptibility,” the investigators wrote. “Hence, herpes zoster infection, presented in this case, was considered the triggering factor of aHUS development.”

At 13 months old, he was again admitted with fever and severe dehydration. Blood tests showed high levels of inflammatory and liver disease markers.

In a clinical exam, doctors also noted he had an upper urinary tract infection, was producing less urine than normal, and had low blood levels of albumin — the most abundant protein found in plasma.

Treatment with antibiotics and albumin failed to elicit a good response. Later, the child developed seizures affecting his left side, and an abnormal posture, with his back extremely arched and stiff legs.

Since this is indicative of brain damage, he underwent a head CT scan and cerebral spinal fluid — the fluid surrounding the brain and spinal cord — was collected and analyzed. No damaging changes were found.

Over the next days, a pulmonary edema (excess fluid in the lungs) necessitated mechanical ventilation for six days together with peritoneal dialysis.

He soon developed pneumonia and became severely anemic; he was returned to intensive care after going into cardiac arrest during a blood transfusion.

Once his condition improved, a kidney biopsy was performed that showed evidence of kidney damage and blood vessel inflammation. A bone marrow analysis also revealed a lack of key immune cells, including B-cells, suggestive of immunodeficiency.

Genetic tests f0und a disease-causing mutation in the ADA gene, confirming a SCID diagnosis.

The boy died at 16 months old, after a severe respiratory infection progressed rapidly and led to multiple organ failure.

“In clinical practice, ADA-SCID patients should be carefully examined in terms of aHUS development possibilities. Furthermore, early treatment in this group of patients is essential, as both conditions, described as severe and life-threatening, are considered to exacerbate each other,” the researchers wrote.

“Various therapies are available and should be induced as soon as possible,” they added.