Proliferative glomerulonephritis with monoclonal IgG deposits in an adolescent successfully treated with daratumumab.

There is no specific treatment for proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID), a disease that is very rare in the pediatric population. We report the case of a 15-year-old boy who presented with mildly reduced kidney function and nephrotic syndrome. Kidney biopsy revealed PGNMID with monoclonal deposits of IgG3 with kappa light chain restriction. Flow cytometry showed a significant CD38 plasma cell population in the peripheral blood in the absence of other signs of hematological malignancy. The patient was treated with a 6-month course of daratumumab, a monoclonal antibody targeting CD38. There was a significant reduction in proteinuria and normalization of kidney function. Based on positive experience with adults, daratumumab should also be studied in children with PGNMID.

Kidney volume and function of low-birth-weight children at 5 years: impact of singleton and twin birth.

BACKGROUND: Many studies have demonstrated the association between low birth weight (LBW) and chronic kidney disease, estimated glomerular filtration rate (eGFR) and kidney volume (KV). However, studies on twins and those investigating numerous perinatal factors beyond LBW, and their associations with various kidney parameters are scarce. METHODS: A two-center cross-sectional study on five-year-old LBW children was conducted between 2021 and 2023. 110 children were enrolled (8 LBW, 58 very LBW (VLBW), 44 extremely LBW (ELBW)); 56 were twins. We examined associations between birth weight (BW), various prenatal, perinatal and postnatal factors, and eGFR, KV, tubular abnormalities and kidney ultrasound abnormalities, both in singletons and twins. RESULTS: In children with ELBW, eGFR correlated with BW (r = 0.55, P = 0.0018), while in those with BW ≥ 1000 g, eGFR remained constant. Other factors associated with decreased eGFR were hypertensive disorder of pregnancy (93.86 vs. 87.26 ml/min/1.73m2, P = 0.0285) in singletons, decreased growth velocity (ß = 0.83, P = 0.0277) in twins, and lower total KV (tKV) and relative KV (rKV) in both singletons (r = 0.60, P < 0.0001 for tKV and r = 0.45, P = 0.0010 for rKV) and twins (ß = 0.34, P < 0.0001 for tKV and ß = 0.23, P = 0.0002 for rKV). Based on the multivariable models excluding KV, BW and gestational age were associated with eGFR in singletons, while male gender, BW, growth velocity, and coffee drinking during pregnancy were associated with eGFR in twins. However, in models that included KV, BW, gestational age and growth velocity were no longer significant. Total KV was associated with BW (r = 0.39, P = 0.0050 for singletons; ß = 2.85, P < 0.0001 for twins), body mass index (r = 0.34, P = 0.0145 for singletons; ß = 8.44, P < 0.0001 for twins), and growth velocity (ß = 1.43, P = 0.0078). Twins born small for gestational age had lower tKV (70.88 vs 89.20 ml, P < 0.0001). Relative KV showed similar associations. Relative kidney volumes were significantly lower for both kidneys compared to the reference population (55.02 vs 65.42 ml/m2, P < 0.0001 for right kidney and 61.12 vs 66.25 ml/m2, P = 0.0015 for left kidney); however, only 8.6% of children had rKV below 10th percentile. CONCLUSION: Many factors affect eGFR and KV, some of them differ between twins and singletons. Based on multivariable models, eGFR seems to be better predicted by KV than by BW and gestational age in LBW children. Relative kidney volumes were significantly lower in our cohort compared to the reference population, but only 8.6% of rKV were below 10th percentile.

Low Birth Weight is Associated with More Severe Course of Steroid-Sensitive Nephrotic Syndrome in Children, Multicentric Study.

BACKGROUND: Several previous studies have reported a more severe course of nephrotic syndrome in children with low birth weight. PATIENTS: Cohort of 223 children with idiopathic nephrotic syndrome. METHODS: We aimed to investigate the association between course of nephrotic syndrome and low birth weight. Data from seven paediatric nephrology centres were used. RESULTS: Children with low birth weight had 3.84 times higher odds for a more severe course of steroid-sensitive nephrotic syndrome (95% CI 1.20-17.22, P=0.041), and those with low birth weight and remission after 7 days had much higher odds for a more severe course of disease (OR 8.7). Low birth weight children had a longer time to remission (median 12 vs. 10 days, P=0.03). They had a higher need for steroid-sparing agents (OR for the same sex=3.26 [95% CI 1.17-11.62, P=0.039]), and the odds were even higher in females with low birth weight (OR 6.81). There was no evidence of an association either between low birth weight and focal segmental glomerulosclerosis or between low birth weight and steroid-resistant nephrotic syndrome. DISCUSSION: We conducted the first multicentric study confirming the worse outcomes of children with NS and LBW and we found additional risk factors. CONCLUSIONS: Low birth weight is associated with a more severe course of steroid-sensitive nephrotic syndrome, while being female and achieving remission after 7 days are additional risk factors.

Severe Acute Kidney Injury in Children as a Rare Complication of Paroxysmal Cold Hemoglobinuria.

Paroxysmal cold hemoglobinuria (PCH) is a rare condition in childhood characterized by complement-mediated premature destruction of red blood cells. PCH is associated with intravascular hemolysis causing hemoglobinuria, which may result in acute kidney injury of various severity. We aimed to retrospectively analyze clinical and laboratory features of children with PCH-associated acute kidney injury received at tertiary Pediatric Hematology and Nephrology Center, University Motol Hospital, Prague, Czech Republic during the period 2016 to 2022. We present here 3 children with PCH-associated acute kidney failure requiring renal replacement therapy. We highlight the association of PCH with kidney disease. Renal parameters and urine examination should be regularly tested in all children with PCH.

Abnormal kidney ultrasound and function in a five-year-old boy born prematurely with a birth weight of 370 grams.

It is known that prematurity and low birth weight are associated with chronic kidney disease and hypertension. A positive correlation between kidney volume and birth weight was also described. In our ongoing observational study in 5-year-old children, we perceived highly abnormal kidney ultrasound and functions of a male patient born weighing 370 grams. It was his first nephrology examination since discharge from the hospital. We believe that thorough follow up and timely diagnosis of developing renal insufficiency may help us to initiate proper treatment in high-risk children (Tab. 1, Fig. 1, Ref. 7). Text in PDF www.elis.sk Keywords: prematurity; extremely low birth weight; chronic kidney disease; renal ultrasound; renal function.

Structural basis of hereditary coproporphyria.

Hereditary coproporphyria is an autosomal dominant disorder resulting from the half-normal activity of coproporphyrinogen oxidase (CPO), a mitochondrial enzyme catalyzing the antepenultimate step in heme biosynthesis. The mechanism by which CPO catalyzes oxidative decarboxylation, in an extraordinary metal- and cofactor-independent manner, is poorly understood. Here, we report the crystal structure of human CPO at 1.58-A resolution. The structure reveals a previously uncharacterized tertiary topology comprising an unusually flat seven-stranded beta-sheet sandwiched by alpha-helices. In the biologically active dimer (K(D) = 5 x 10(-7) M), one monomer rotates relative to the second by approximately 40 degrees to create an intersubunit interface in close proximity to two independent enzymatic sites. The unexpected finding of citrate at the active site allows us to assign Ser-244, His-258, Asn-260, Arg-262, Asp-282, and Arg-332 as residues mediating substrate recognition and decarboxylation. We favor a mechanism in which oxygen serves as the immediate electron acceptor, and a substrate radical or a carbanion with substantial radical character participates in catalysis. Although several mutations in the CPO gene have been described, the molecular basis for how these alterations diminish enzyme activity is unknown. We show that deletion of residues (392-418) encoded by exon six disrupts dimerization. Conversely, harderoporphyria-causing K404E mutation precludes a type I beta-turn from retaining the substrate for the second decarboxylation cycle. Together, these findings resolve several questions regarding CPO catalysis and provide insights into hereditary coproporphyria.