The effects of transitioning from immediate release to extended release cysteamine therapy in Norwegian patients with nephropathic cystinosis: a retrospective study.

Background: Nephropathic cystinosis is a rare lysosomal storage disorder in which accumulation of cystine and formation of crystals particularly impair kidney function and gradually lead to multi-organ dysfunction. Lifelong therapy with the aminothiol cysteamine can delay the development of kidney failure and the need for transplant. The purpose of our long-term study was to explore the effects of transitioning from immediate release (IR) to extended release (ER) formulation in Norwegian patients in routine clinical care.

Focal segmental glomerulosclerosis and proteinuria associated with Myo1E mutations: novel variants and histological phenotype analysis.

Background: Pathogenic mutations in the non-muscle single-headed myosin, myosin 1E (Myo1e), are a rare cause of pediatric focal segmental glomerulosclerosis (FSGS). These mutations are biallelic, to date only reported as homozygous variants in consanguineous families. Myo1e regulates the actin cytoskeleton dynamics and cell adhesion, which are especially important for podocyte functions.

Accuracy of single intravenous access iohexol GFR in children is hampered by marker contamination.

Measurement of glomerular filtration rate (GFR) in children by iohexol injection and blood sampling from the contralateral arm is widely used. A single intravenous access for iohexol injection and subsequent blood sampling has the obvious advantages of being less painful and easier to perform. The purpose of our study was to determine if blood samples drawn from the injection access are feasible and accurate for iohexol GFR (iGFR) measurements.

Expanding the phenotypic spectrum of BCS1L-related mitochondrial disease.

Objective: To delineate the full phenotypic spectrum of BCS1L-related disease, provide better understanding of the genotype-phenotype correlations and identify reliable prognostic disease markers.

Methods: We performed a retrospective multinational cohort study of previously unpublished patients followed in 15 centres from 10 countries. Patients with confirmed biallelic pathogenic BCS1L variants were considered eligible.

Estimating glomerular filtration rate in children: evaluation of creatinine- and cystatin C-based equations.

Background: Glomerular filtration rate (GFR) estimated by creatinine- and/or cystatin C-based equations (eGFR) is widely used in daily practice. The purpose of our study was to compare new and old eGFR equations with measured GFR (mGFR) by iohexol clearance in a cohort of children with chronic kidney disease (CKD).

Methods: We examined 96 children (median age 9.

Iohexol plasma clearance in children: validation of multiple formulas and single-point sampling times.

Background: The non-ionic agent iohexol is increasingly used as the marker of choice for glomerular filtration rate (GFR) measurement. Estimates of GFR in children have low accuracy and limiting the number of blood-draws in this patient population is especially relevant. We have performed a study to evaluate different formulas for calculating measured GFR based on plasma iohexol clearance with blood sampling at only one time point (GFR1p) and to determine the optimal sampling time point.

Renal Function Influences Diagnostic Markers in Serum and Urine: A Study of Guanidinoacetate, Creatine, Human Epididymis Protein 4, and Neutrophil Gelatinase-Associated Lipocalin in Children.

Background: Impaired renal function may affect the level of diagnostic disease markers. The aim of the study was to investigate the effect of measured glomerular filtration rate (GFR) on 4 diagnostic markers in blood and urine-guanidinoacetate (GAA), creatine (CRE), human epididymis protein 4 (HE4), and neutrophil gelatinase-associated lipocalin (NGAL)-and how this could affect the decision and reference limits.

Methods: We examined 96 children (median age 9.

Iohexol plasma clearance in children: validation of multiple formulas and two-point sampling times.

Background: In children, estimated glomerular filtration rate (eGFR) methods are hampered by inaccuracy, hence there is an obvious need for safe, simplified, and accurate measured GFR (mGFR) methods. The aim of this study was to evaluate different formulas and determine the optimal sampling points for calculating mGFR based on iohexol clearance measurements on blood samples drawn at two time points (GFR2p).

Methods: The GFR of 96 children with different stages of chronic kidney disease (CKD) (median age 9.

Glomerular filtration rate measured by iohexol clearance: A comparison of venous samples and capillary blood spots.

Background: Glomerular filtration rate (GFR) measured by iohexol clearance using venous samples is widely used. Capillary sampling on filter paper is easier to perform, may be less painful and spares the blood volume. The purpose of the study was to validate a blood spot method for measuring GFR in children aged 6 years or younger suffering from chronic kidney disease (CKD).

NPHS2 mutations in steroid-resistant nephrotic syndrome: a mutation update and the associated phenotypic spectrum.

Mutations in the NPHS2 gene encoding podocin are implicated in an autosomal-recessive form of nonsyndromic steroid-resistant nephrotic syndrome in both pediatric and adult patients. Patients with homozygous or compound heterozygous mutations commonly present with steroid-resistant nephrotic syndrome before the age of 6 years and rapidly progress to end-stage kidney disease with a very low prevalence of recurrence after renal transplantation. Here, we reviewed all the NPHS2 mutations published between October 1999 and September 2013, and also all novel mutations identified in our personal cohort and in international genetic laboratories.

Familial diarrhea syndrome caused by an activating GUCY2C mutation.

Background: Familial diarrhea disorders are, in most cases, severe and caused by recessive mutations. We describe the cause of a novel dominant disease in 32 members of a Norwegian family. The affected members have chronic diarrhea that is of early onset, is relatively mild, and is associated with increased susceptibility to inflammatory bowel disease, small-bowel obstruction, and esophagitis.

Spectrum of mutations in the renin-angiotensin system genes in autosomal recessive renal tubular dysgenesis.

Autosomal recessive renal tubular dysgenesis (RTD) is a severe disorder of renal tubular development characterized by early onset and persistent fetal anuria leading to oligohydramnios and the Potter sequence, associated with skull ossification defects. Early death occurs in most cases from anuria, pulmonary hypoplasia, and refractory arterial hypotension. The disease is linked to mutations in the genes encoding several components of the renin-angiotensin system (RAS): AGT (angiotensinogen), REN (renin), ACE (angiotensin-converting enzyme), and AGTR1 (angiotensin II receptor type 1).

Ciliopathies with skeletal anomalies and renal insufficiency due to mutations in the IFT-A gene WDR19.

A subset of ciliopathies, including Sensenbrenner, Jeune, and short-rib polydactyly syndromes are characterized by skeletal anomalies accompanied by multiorgan defects such as chronic renal failure and retinitis pigmentosa. Through exome sequencing we identified compound heterozygous mutations in WDR19 in a Norwegian family with Sensenbrenner syndrome. In a Dutch family with the clinically overlapping Jeune syndrome, a homozygous missense mutation in the same gene was found.

Thrombotic microangiopathy mimicking membranoproliferative glomerulonephritis.

A 4-year-old boy presented with proteinuria and developed progressive renal failure over 6 years. In the patient's family, five individuals were affected with atypical haemolytic uraemic syndrome (aHUS) but not the patient. Renal biopsies (n = 3) showed glomerular basement membrane thickening with double contours, endothelial swelling and deposits of C3 and C1q.

Clinical aspects of a nationwide epidemic of severe haemolytic uremic syndrome (HUS) in children.

Background: Report a nationwide epidemic of Shiga toxin-producing E. coli (STEC) O103:H25 causing hemolytic uremic syndrome (D+HUS) in children.

Methods: Description of clinical presentation, complications and outcome in a nationwide outbreak.