PMC7381106_01
Evolution of hematological parameters and renal activity. Graphics show the blood test determinations since the day of admission (10-Oct-2014) to the day of discharge (15-Oct-2014) and then of the successive routine controls in the following years. Dotted lines represent the upper or minimum value of each parameter from which it is considered pathogenic (hemoglobin > 11.5 g/dl; platelets < 150/ml; LDH > 220 U/L; urine protein/creatinine > 20 mug/mumol; creatinine > 61 mumol/l; C3 < 85 mg/dl).
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F1
Eight hours later, hemoglobin decreased to 10 g/dl and platelets to 28,900/mul; lactate dehydrogenase (LDH) was determined to be 1,657 U/L (<220 U/L) (Figure 1). He was discharged on the sixth day with hemoglobin of 10.8 g/dl, platelets of 201,000/mul, LDH of 639 U/L, creatinine of 65 mumol/L, and UPr/UCr of 34 mug/mumol (Figure 1). However, decreased C3 levels (46-62 mg/dl) (Figure 1) persisted, and subsequent analysis of factor B plasma levels revealed that they were in the lower part of the normal range (85-170 mug/ml) (Figure 2).
C3S179P is a novel de novo gain-of-function mutations that impairs regulation by MCP. (A) Pedigree depicting the segregation of CFH and MCP polymorphisms organized in haplotype blocks. Single nucleotide polymorphisms are identified by their "rs" numbers. In black are the haplotypes inherited by the patient, identified by a solid square. Asterisk identifies the CFH-H3 aHUS risk haplotype. Plasma levels of C3 and factor B (FB) are indicated for each individual. The patient is the only member of the pedigree carrying the C3S179P mutation. (B) C3 purified from the plasma-ethylenediaminetetraacetic acid (EDTA) of the patient activates normally to C3b by factor B (FB) and factor D (FD). Briefly, C3 was purified using a combination of sodium sulfate precipitation, lysine-sepharose chromatography, DEAE-Sepharose anion exchange chromatography, and Mono S HR 5/5 cation exchange chromatography as previously described. (C) C3b generated from the patient's C3 shows a marked resistant to inactivation by factor I in the presence of MCP. Differences between slopes were tested with a general linear model (GLM), with "time" as an integer variable and "strain" as a nominal one. The time x strain interaction was considered as the estimator of the differences between slopes. MCP (p < 10-8). FH (p = 0.002).
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F2
However, decreased C3 levels (46-62 mg/dl) (Figure 1) persisted, and subsequent analysis of factor B plasma levels revealed that they were in the lower part of the normal range (85-170 mug/ml) (Figure 2). Interestingly, none of his parents present this C3 variation (Figure 2A). The patient carries the CFH-H3 aHUS risk polymorphism in heterozygosis, inherited from his father (Figure 2A). Briefly, when purified C3 from the patient was incubated with FB and FD, it completely activated to C3b, suggesting that C3S179P is normally activated by the AP C3 convertase (Figure 2B). When the patient C3b was tested for inactivation by FI in the presence of FH or MCP, we found that it was resistant to inactivation by FI in the presence of both cofactors, but much more resistant when MCP was the cofactor (Figure 2C).