Beata Bieniaś

Acute renal failure due to bilateral xanthine urolithiasis in a boy with Lesch-Nyhan syndrome.

Lesch-Nyhan syndrome is a very rare X-linked recessive disorder caused by mutation in the gene encoding enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). A complete deficiency of HPRT leads to severe purine overproduction and to uric acid renal lithiasis as a consequence. This may be effectively prevented by administration of allopurinol; however, its overdosage may result in xanthinuria and xanthine urolithiasis. We report on a 9-year-old boy with Lesch-Nyhan syndrome who developed acute renal failure due to bilateral staghorn xanthine urolithiasis resulting from long-term treatment with excessive doses of allopurinol. To the best of our knowledge, the presented case is the first one in the literature.

Retrospective cohort study of familial hypomagnesaemia with hypercalciuria and nephrocalcinosis due to CLDN16 mutations

BACKGROUND Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare autosomal recessive tubular disorder exhibiting a high risk for progressive chronic kidney disease (CKD). METHODS This is a retrospective multicentre study of 25 paediatric cases with FHHNC in Poland. Median age at diagnosis was 4 years and median follow-up time was 4.8 years. RESULTS All cases of FHHNC carried recessive mutations in CLDN16. The founder mutation in CLDN16, Leu151Phe, was the most frequent cause of FHHNC in Polish patients, with 13 (52%) cases being homozygous and 5 (20%) carrying Leu151Phe allele in compound heterozygosity. All cases showed nephrocalcinosis, increased urinary fractional excretion of magnesium and hypercalciuria. Other disease features included hypomagnesaemia (76%), hyperparathyroidism (76%), hyperuricaemia (56%) and hypocitraturia (60%). Treatment with thiazides effectively reduced hypercalciuria in most cases. During follow-up, renal function declined in 60% of patients; 12% of patients reached CKD stage 3 or 4 and one patient developed end-stage renal failure. CONCLUSIONS We report one of the largest cohorts of FHHNC cases caused by CLDN16 mutations. A missense variant of CLDN16, Leu151Phe, is the most common mutation responsible for FHHNC in Poland. Additionally, we found that normomagnesaemia does not exclude FHHNC and the calculation of fractional excretion of Mg can be diagnostic in the setting of normomagnesaemia. We also demonstrate the efficacy of a treatment with thiazides in terms of hypercalciuria in the majority of patients.

Erratum to: Relationship between serum IgA/C3 ratio and severity of histological lesions using the Oxford classification in children with IgA nephropathy

Background The aim of this study was to evaluate the usefulness of serum immunoglobulin A/complement factor 3 (IgA/C3) ratio for predicting histological severity of kidney lesions in children with IgA nephropathy (IgAN) based on World Health Organization (WHO) and the Oxford classification (OC).

Early Markers of Tubulointerstitial Fibrosis in Children With Idiopathic Nephrotic Syndrome: Preliminary Report.

Abstract Tubulointerstitial fibrosis and tubular atrophy play a crucial role in the pathogenesis of chronic kidney disease (CKD). They are also major determinants in chronic kidney disease development and progression in patients with primary renal diseases characterized by persistent or recurrent proteinuria. The purpose of the study was to assess urinary excretion of alpha-glutathione S-transferase (alpha-GST), pi-glutathione S-transferase (pi-GST), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and serum NGAL level in children with idiopathic nephrotic syndrome (INS). Patients and methods: the study group comprised of 39 children with INS and the control group consisted of 20 healthy children. A total of 23 patients were affected with steroid-dependent nephrotic syndrome (SDNS) and 16 with steroid-resistant nephrotic syndrome (SRNS). In the majority of patients, a histopathologic examination revealed minimal change disease (MCD)—25 (64%). Focal segmental glomerulosclerosis (FSGS), mesangioproliferative glomerulonephritis (MesPGN), membranoproliferative glomerulonephritis (MPGN), and membranous glomerulonephritis (MGN) were diagnosed in 4 (10.3 %), 6 (15.5%), 2 (5.1%), and 2 (5.1%) children, respectively. Urinary alpha-GST, urinary pi-GST, urinary KIM-1, and urinary and serum NGAL concentrations were measured using specific enzyme-linked immunosorbent assay. The urinary results were expressed in nanograms per milligram of creatinine (ng/mg). Results: The authors observed significantly higher levels of urinary alpha-GST/creatinine ratio (P = 0.03), urinary KIM-1/creatinine ratio (P < 0.02), serum NGAL level (P < 0.01), and urinary NGAL/creatinine ratio (P = 0.02) in children with INS compared with controls. The median values of urinary pi-GST/creatinine ratio in children with INS and controls did not differ significantly. In children with SRNS, the median values of urinary NGAL/creatinine ratio (P = 0.02) and urinary KIM-1/creatinine ratio (P = 0.02) were significantly higher compared with children with SDNS. The authors noted significant positive correlation between KIM-1/creatinine ratio and proteinuria (r = 0.56, P < 0.05). The analysis of alpha-GST/creatinine ratio, pi-GST/creatinine ratio, sNGAL, and uNGAL/creatinine ratio concerning the histopathologic examination, the duration of the disease, and number of relapses did not show any significant differences. Conclusions: 1. Both children with SDNS and those with SRNS were characterized by increased tubular injury marker levels. 2. Patients with SRNS and higher proteinuria are more susceptible to early kidney damage.

Low renal but high extrarenal phenotype variability in Schimke immuno-osseous dysplasia

Schimke immuno-osseous dysplasia (SIOD) is a rare multisystem disorder with early mortality and steroid-resistant nephrotic syndrome (SRNS) progressing to end-stage kidney disease. We hypothesized that next-generation gene panel sequencing may unsurface oligosymptomatic cases of SIOD with potentially milder disease courses. We analyzed the renal and extrarenal phenotypic spectrum and genotype-phenotype associations in 34 patients from 28 families, the largest SMARCAL1-associated nephropathy cohort to date. In 11 patients the diagnosis was made unsuspectedly through SRNS gene panel testing. Renal disease first manifested at median age 4.5 yrs, with focal segmental glmerulosclerosis or minimal change nephropathy on biopsy and rapid progression to end-stage kidney disease (ESKD) at median age 8.7 yrs. Whereas patients diagnosed by phenotype more frequently developed severe extrarenal complications (cerebral ischemic events, septicemia) and were more likely to die before age 10 years than patients identified by SRNS-gene panel screening (88 vs. 40%), the subgroups did not differ with respect to age at proteinuria onset and progression to ESKD. Also, 10 of 11 children diagnosed unsuspectedly by Next Generation Sequencing were small at diagnosis and all showed progressive growth failure. Severe phenotypes were usually associated with biallelic truncating mutations and milder phenotypes with biallelic missense mutations. However, no genotype-phenotype correlation was observed for the renal disease course. In conclusion, while short stature is a reliable clue to SIOD in children with SRNS, other systemic features are highly variable. Our findings support routine SMARCAL1 testing also in non-syndromic SRNS.

Do children with end-stage renal disease live shorter? Analysis of mortality on the basis of data from the Polish Registry of Renal Replacement Therapy in Children

PURPOSE The mortality of patients with end-stage renal disease (ESRD) is much higher than that of the general population. To date no data has been published on the mortality of children with ESRD in Poland. The aim of this study was to compare the risk of death for pediatric patients on renal replacement therapy (RRT) with that of the general pediatric population and to identify the risk factors of death. MATERIAL/METHODS Data of 779 children with ESRD registered in the Polish Registry of Children on RRT was analyzed. The relative risk of death was calculated as the ratio of the mortality rate in ESRD patients to the mortality rate in age-adjusted general population. RESULTS The mortality rate of children with ESRD was 74-fold higher than that of the age- and gender-adjusted general pediatric population (4.05 vs. 0.05/100 person-years). The highest mortality rate (4.53/100 patient-years) was found in the youngest age group. Younger age and duration of dialysis therapy were identified as mortality risk factors. The major causes of death in ESRD patients were infections and cardiovascular complications, whereas deaths in general child population were mainly due to accidents or congenital defects. CONCLUSIONS The mortality in Polish children with ESRD is 74-fold higher than that of the general pediatric population. Infections, followed by cardiovascular complications, constitute the main causes of mortality in children subjected to RRT. The risk of death is the highest among children who started RRT at a younger age and in those subjected to long-term dialysis treatment.

Potential Novel Biomarkers of Obstructive Nephropathy in Children with Hydronephrosis

Obstructive nephropathy (ON) secondary to the congenital hydronephrosis (HN) is one of the most common causes of chronic kidney disease in children. Neither currently used imaging techniques nor conventional laboratory parameters are sufficient to assess the onset and outcome of this condition; hence, there is a need to prove the usefulness of newly discovered biomarkers of kidney injury in this respect. The purpose of the study was to assess the urinary excretion of alpha-GST, pi-GST, NGAL, and KIM-1 and the serum level of NGAL in children with congenital unilateral hydronephrosis secondary to ureteropelvic junction obstruction. The results were evaluated in relation to severity of HN, the presence of ON, relative function of an obstructed kidney, and the presence of proteinuria. The study comprised 45 children with HN of different grades and 21 healthy controls. Urinary and serum concentrations of biomarkers were measured using specific ELISA kits. Urinary biomarker excretions were expressed as a biomarker/creatinine (Cr) ratio. Patients with the highest grades of HN showed significantly increased values of all measured biomarkers, whereas those with the lowest grades of HN displayed only significant elevation of urinary alpha-GST and the serum NGAL. Urinary NGAL positively correlated with percentage loss of relative function of an obstructed kidney in renal scintigraphy. In patients with proteinuria, significantly higher urinary alpha-GST excretion was revealed as compared to those without this symptom. The ROC curve analysis showed the best diagnostic profile for urinary alpha-GST/Cr and NGAL/Cr ratios in the detection of ON. In conclusion, the results of the study showed that urinary alpha-GST and NGAL are promising biomarkers of ON. Ambiguous results of the remaining biomarkers, i.e., urinary pi-GST and KIM-1, and serum NGAL level may be related to a relatively small study group. Their utility in an early diagnosis of ON should be reevaluated.

Serum GDIgA1 levels in children with IgA nephropathy and Henoch-Schönlein nephritis

Introduction GDIgA1 (galactose deficient IgA1) plays a significant role in the pathogenesis of IgA nephropathy (IgAN) and Henoch-Schönlein nephritis (HSN). Aim of the study The aim of this study was to assess the relevance of serum GDIgA1 level as a prognostic marker in children with IgAN and HSN. Material and methods 41 children were included to the study group (15 IgAN, 26 HSN) and 22 to the control group. The following parameters were evaluated at baseline and endpoint: proteinuria, erythrocyturia, serum creatinine, serum IgA, GFR. A kidney biopsy was performed in all patients and evaluated according to the Oxford Classification (1 – present, 0 – absent: M – mesangial hypercellularity; E– endocapillary hypercellularity; S – segmental sclerosis/adhesion; T – tubular atrophy/interstitial fibrosis), and was calculated as the total score (sum of M, E, S, T). At the end of follow-up, the serum GDIgA1 concentration was measured. Results The serum GDIgA1 concentration in patients with IgAN and HSN was significantly higher than in the control group. No significant differences in mean proteinuria, erythrocyturia, GFR, MEST score, or GDIgA1 in serum, as well as the duration of follow-up between IgAN and HSN were observed. Baseline serum IgA concentration and time to kidney biopsy were significantly higher in children with IgAN than in children with HSN. We observed a positive correlation between GDIgA1 and IgA levels (r = 0.53), and GDIgA1 and serum creatinine levels (r = 0.5), as well as negative correlation between GDIgA1 and GFR (r = –0.37). Conclusions Serum GDIgA1 level may have a prognostic value in children with IgAN and HSN; however, to fully elucidate its clinical potential further studies performed in larger patient cohorts are required.

Nephrotic syndrome in the course of Schimke immuno-osseous dysplasia (SIOD) – case report

Zespół Schimke (SIOD – Schimke immunoosseous dysplasia) jest bardzo rzadkim, genetycznie uwarunkowanym schorzeniem, rozwijającym się w związku z mutacjami genu SMARCAL1. Charakteryzuje się wielonarządowymi zmianami, do których należą postępująca nefropatia, zaburzenia immunologiczne, hematologiczne, nieprawidłowości kostne oraz dysmorfia twarzy i zmiany skórne. W pracy przedstawiono przypadek chłopca z SIOD z początkowo skąpoobjawowym pozanerkowym fenotypem. U pacjenta w 3 r.ż. rozpoznano białkomocz z towarzyszącym nadciśnieniem tętniczym, w wieku 6 lat nastąpiła progresja nefropatii do pierwotnie steroidoopornego zespołu nerczycowego. Biopsja nerki wykazała zmianę minimalną, a terapia cysklosporyną A doprowadziła do remisji po 5 tygodniach leczenia. Podczas 6-letniej obserwacji nie występowały nawroty zespołu nerczycowego, obserwowane były natomiast epizody subnerczycowego białkomoczu przy prawidłowej funkcji nerek. Objawy pozanerkowe obejmowały opóźnione wzrastanie wewnątrzmaciczne, od 3 r.ż. leukopenię, natomiast niskorosłość, wyraźne cechy dysmorfii i ciemne plamki na skórze, charakterystyczne dla SIOD, obserwowano dopiero w kolejnych latach choroby. Wówczas ujawniono również typową dla tego zespołu dysplazję kręgowo-nasadową. Przeprowadzona diagnostyka genetyczna wykazała mutację genu SMARCAL1. Podsumowując, nefropatia w przebiegu zespołu Schimke może początkowo występować jako dominujący objaw choroby. Może rozwijać się jako zespół nerczycowy na podłożu zmiany minimalnej i ulegać remisji w wyniku leczenia cyklosporyną A przy zachowaniu prawidłowej funkcji nerek w kilkuletnim okresie obserwacji.

Congenital chloride diarrhea primary treated as Bartter syndrome – case report

1Klinika Nefrologii Dziecięcej, Uniwersytet Medyczny w Lublinie 2Klinika Patologii Noworodków i Niemowląt, Uniwersytet Medyczny w Lublinie 3Specjalistyczny Zakład Opieki Zdrowotnej nad Matką i Dzieckiem w Poznaniu 4Department of Pediatrics, Seoul National University Children’s Hospital, Seoul, Korea; Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea; Kidney Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea