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Published on: December 31, 2015
Renal-Limited Thrombotic Microangiopathy in Infants: A Case Series
Haiyan Wang1,2, Shuting Luo1, Sijin Wang1
1Department of Pediatrics, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Rationale & Objective:
Thrombotic microangiopathy (TMA), an intractable disease, can present in a renal-limited mode. Data on infantile-onset renal-limited TMA (RL-TMA) is lacking. This study describes 5 cases of RL-TMA in infants.
Study Design:
Case series.
Setting & Participants:
Five patients with infantile-onset RL-TMA who were admitted and/or followed up at Nanfang Hospital, Southern Medical University, from January 2024 to June 2025.
Analytical Approach:
Clinical data of 5 patients were collected. Amino acid conservation was analyzed by Clustal Omega, the secondary structure of the mutants was predicted by PolyPhen-2 and PHYRE2, and tertiary structure was predicted by AlphaFold3 and ChimeraX.
Results:
All patients presented with acute nephritic syndrome with hematuria and proteinuria with onset in infancy, but without hemolytic anemia or thrombocytopenia. Corticosteroid treatment was attempted in 3 patients with no response. Renal pathology revealed microthrombi; segmental endothelial cells that swelled with widening of the subendothelial gap and/or mesangiolysis were observed. C3 heterozygous missense variant (c.2184 C>T, p.Cys728X), CD46 homozygous variant c.614A>G (p.Glu205Gly), and CFI heterozygous variant c.610A>G (p.Met204Val) were detected in 3 patients, respectively. Possible activation of alternative complement pathway (AP) was indicated in all 4 tested patients. Complete remission was achieved in 2 patients, and partial response was observed in another 2 patients who received eculizumab therapy. The patient who harbored the CFI variation and did not receive eculizumab therapy progressed to kidney failure at 11 months of age.
Limitations:
Functional verification of genetic variants of C3, CD46 and CFI in this study were not implemented. AP activation-related factors were not checked in patient 5.
Conclusions:
RL-TMA can occur in infancy, which has not been reported previously. Activation of the AP may be the common cause of infantile-onset RL-TMA. Its diagnosis and therapy are challenging. Promising outcomes can be achieved with eculizumab therapy.
