Eculizumab Rescue Therapy in Patients With Recurrent Atypical Hemolytic Uremic Syndrome After Kidney Transplantation.

Introduction: Since 2016, kidney transplantation in patients with atypical hemolytic uremic syndrome (aHUS) in the Netherlands is performed without eculizumab prophylaxis. Eculizumab is given in case of posttransplant aHUS recurrence. Eculizumab therapy is monitored in the CUREiHUS study. Methods: All participating kidney transplant patients who received eculizumab therapy for a suspected posttransplant aHUS recurrence were evaluated. Overall recurrence rate was monitored prospectively at Radboud University Medical Center. Results: In the period from January 2016 until October 2020, we included 15 (12 females, 3 males; median age 42 years, range 24-66 years) patients with suspected aHUS recurrence after kidney transplantation in this study. The time interval to recurrence showed a bimodal distribution. Seven patients presented early after transplantation (median 3 months, range 0.3-8.8 months), with typical aHUS features: rapid loss of estimated glomerular filtration rate (eGFR) and laboratory signs of thrombotic microangiopathy (TMA). Eight patients presented late (median 46 months, range 18-69 months) after transplantation. Of these, only 3 patients had systemic TMA, whereas 5 patients presented with slowly deteriorating eGFR without systemic TMA. Treatment with eculizumab resulted in improvement or stabilization of eGFR in 14 patients. Eculizumab discontinuation was tried in 7 patients; however, it was successful only in 3. At the end of the follow-up (median 29 months, range 3-54 months after start of eculizumab), 6 patients had eGFR <30 ml/min per 1.73 m2. Graft loss had occurred in 3 of them. Overall, aHUS recurrence rate without eculizumab prophylaxis was 23%. Conclusions: Rescue treatment of posttransplant aHUS recurrence is effective; however, some patients suffer from irreversible loss of kidney function, likely caused by delayed diagnosis and treatment and/or too aggressive discontinuation of eculizumab. Physicians should be aware that recurrence of aHUS can present without evidence of systemic TMA.

REducing STEroids in Relapsing Nephrotic syndrome: the RESTERN study- protocol of a national, double-blind, randomised, placebo-controlled, non-inferiority intervention study.

INTRODUCTION: Oral corticosteroids are the first-line treatment for idiopathic childhood nephrotic syndrome. Most children experience several relapses, needing repeated courses of corticosteroid therapy. This exposes them to side effects and long-term complications. For most patients, long-term prognosis is for complete resolution of the disease over time and maintenance of normal kidney function. Therefore, it is vital to focus on minimising adverse events of the disease and its therapy. Unfortunately, no randomised controlled trials are available to determine the optimal corticosteroid treatment of an infrequent relapse of nephrotic syndrome. Recent studies show that treatment schedules for the first episode can safely be shortened to 2 months. The hypothesis of the REducing STEroids in Relapsing Nephrotic syndrome (RESTERN) study is that a 4-week reduction of alternate-day steroids after inducing remission is effective and safe, reduces steroid exposure by 35% on average and is therefore preferable. METHODS AND ANALYSIS: The RESTERN study is a nationwide, double-blind, randomised, placebo-controlled, non-inferiority intervention study. Children aged 1-18 years with a relapse of steroid-sensitive nephrotic syndrome are eligible for this study. Study subjects (n=144) will be randomly assigned to either current standard therapy in the Netherlands or a reduced prednisolone schedule. The primary outcome of the RESTERN study is the time to first relapse after the final prednisolone dose. The secondary outcomes are the number or relapses, progression to frequent relapsing or steroid dependent nephrotic syndrome and the cumulative dosage of prednisolone during the study period. ETHICS AND DISSEMINATION: This non-inferiority trial will be performed in accordance with the Declaration of Helsinki and has been approved by the medical ethical committee of Arnhem-Nijmegen and the Dutch Competent Authority (Central Committee on Research Involving Human Subjects, CCMO). After completion of this study, results will be published in national and international peer-reviewed scientific journals. Papers will be published according to CCMO guidelines. The final report will be made available to trial participants. TRIAL REGISTRATION NUMBER: NTR5670, EudraCT no 2016-002430-76.

Adult-onset congenital thrombotic thrombocytopenic purpura caused by a novel compound heterozygous mutation of the ADAMTS13 gene.

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease, characterized by microangiopathic hemolytic anaemia and thrombocytopenia, resulting in neurologic and/or renal abnormalities. We report a 49-year-old patient with a history of thrombotic events, renal failure, and thrombocytopenia. Blood analysis demonstrated no ADAMTS13 activity in the absence of antibodies against ADAMTS13. The complete ADAMTS13 gene was sequenced, and two mutations were identified: one mutation on exon 24 (Arg1060Asp), which had previously been described, and a mutation on exon 27 (Met1260IlefsX34), which has not been reported. For these mutations, compound heterozygosity appears to be necessary to cause TTP, as family members of the patient display only one of the mutations and all displayed normal ADAMTS13 activity.

Natural disease course and genotype-phenotype correlations in Complex I deficiency caused by nuclear gene defects: what we learned from 130 cases.

Mitochondrial complex I is the largest multi-protein enzyme complex of the oxidative phosphorylation system. Seven subunits of this complex are encoded by the mitochondrial and the remainder by the nuclear genome. We review the natural disease course and signs and symptoms of 130 patients (four new cases and 126 from literature) with mutations in nuclear genes encoding structural complex I proteins or those involved in its assembly. Complex I deficiency caused by a nuclear gene defect is usually a non-dysmorphic syndrome, characterized by severe multi-system organ involvement and a poor prognosis. Age at presentation may vary, but is generally within the first year of life. The most prevalent symptoms include hypotonia, nystagmus, respiratory abnormalities, pyramidal signs, dystonia, psychomotor retardation or regression, failure to thrive, and feeding problems. Characteristic symptoms include brainstem involvement, optic atrophy and Leigh syndrome on MRI, either or not in combination with internal organ involvement and lactic acidemia. Virtually all children ultimately develop Leigh syndrome or leukoencephalopathy. Twenty-five percent of the patients died before the age of six months, more than half before the age of two and 75 % before the age of ten years. Some patients showed recovery of certain skills or are still alive in their thirties . No clinical, biochemical, or genetic parameters indicating longer survival were found. No clear genotype-phenotype correlations were observed, however defects in some genes seem to be associated with a better or poorer prognosis, cardiomyopathy, Leigh syndrome or brainstem lesions.

Normal biochemical analysis of the oxidative phosphorylation (OXPHOS) system in a child with POLG mutations: a cautionary note.

We report a 5-year-old child carrying polymerase gamma (POLG1) mutations, but strikingly normal oxidative phosphorylation analysis in muscle, fibroblasts and liver. Mutations in POLG1 have so far been described in children with severe combined oxidative phosphorylation (OXPHOS) deficiencies and with the classical Alpers-Huttenlocher syndrome. The patient presented with a delayed psychomotor development and ataxia during the first two years of life. From the third year of life he developed epilepsy and regression in development, together with symptoms of visual impairment and sensorineuronal deafness. Cerebrospinal fluid showed elevated lactic acid and protein concentrations. An elder brother had died due to combined OXPHOS deficiencies. Despite the clinical similarity with the elder brother, except for liver involvement, the OXPHOS system analysis in a frozen muscle biopsy was normal. For this reason a fresh muscle biopsy was performed, which has the advantage of the possibility of measuring the substrate oxidation rates and ATP production, part of the mitochondrial energy-generating system (MEGS). During the same session, biopsies of liver and fibroblasts were taken. These three tissues showed normal measurements of the MEGS capacity. Based on the phenotype of Alpers-Huttenlocher syndrome in the elder brother, we decided to screen the POLG1 gene. Mutation analysis showed compound heterozygosity with two known mutations, A467T and G848S. The normal MEGS capacity in this patient expands the already existing complexity and heterogeneity of the childhood POLG1 patients and, on the basis of the high frequency of POLG1 mutations in childhood, warrants a liberal strategy with respect to mutation analysis.

[From gene to disease; the haemolytic uraemic syndrome can be caused by mutations in regulating factors of the alternative route of the complement system]. / Van gen naar ziekte; het hemolytisch-uremisch syndroom als gevolg van mutaties in de regulatie van de alternatieve route van het complementsysteem.

Defective control of the alternative route of the complement system is an important cause of the non-diarrhoea haemolytic uraemic syndrome (HUS). On the endothelial surface, mutations in HF1, MCP and IF predispose to development ofHUS. Uncontrolled complement activation on the surface of endothelial cells will damage these cells extensively. Plasmapheresis can be an effective, although temporary, treatment for mutations in HF1 and IF. HUS frequently recurs after renal transplantation in patients with HF1 or IF mutations but not in patients with a mutation of MCP. These genetic defects can be detected by routine diagnostics.

Selection and characterization of a unique phage display-derived antibody against dermatan sulfate.

Dermatan sulfate (DS) is a member of the glycosaminoglycan (GAG) family and is primarily located in the extracellular matrix. Using a modified phage display procedure, we selected 2 different antibodies against DS of which one antibody, LKN1, was specific for DS. LKN1 was especially reactive with 4/2,4-di-O-sulfated DS, and did not react with other classes of GAGs including chondroitin sulfate and heparan sulfate. Immunohistochemical analysis of kidney, skin and tendon showed a typical fibrillar staining pattern, co-localizing with type I collagen. Staining was abolished by specific enzymatic digestion of DS. Immunoelectron microscopy confirmed the association of the DS epitope with collagen fibrils. The location of DS did not follow the main banding period of collagen, which is in line with the current concept that the core protein rather than the DS moiety of DS-proteoglycans specifically binds to collagen fibrils. This unique anti-DS antibody and the availability of its coding DNA may be instrumental in studies of the structure and function of DS.

Distal spinal muscular atrophy as a major feature in adult-onset ataxia telangiectasia.

The authors report four adult-onset ataxia telangiectasia (AT) patients belonging to two families lacking pronounced cerebellar ataxia but displaying distal spinal muscular atrophy. AT was proven by genetic studies showing ATM mutations and a reduced level of ATM. ATM activity, as measured by phosphorylation of p53, was close to normal, indicating that the p53 response is not the only factor in preventing neural damage in anterior horn cells in AT.

[A genetic childhood disease with consequences in adult life: the Denys-Drash syndrome]. / Een genetische kinderziekte met gevolgen op de volwassen leeftijd: Denys-Drash-syndroom.

In a 17-year-old woman with absent sexual development and a congenital nephrotic syndrome leading to renal failure, the Denys-Drash syndrome was diagnosed after development of an ovarian dysgerminoma. The Denys-Drash syndrome is characterised by the triad: progressive nephropathy due to diffuse mesangial sclerosis, male pseudo-hermaphroditism (XY karyotype with ambiguous or female genital organs) and an increased risk of developing Wilms' tumour and gonadoblastoma. The syndrome is generally caused by a genetic defect in the Wilms' tumour suppressor 1 gene (WT1 gene). A WT1 mutation and XY karyotype were also found in this patient. The WT1 gene encodes a transcription factor playing an important role in renal and genital development. The diagnosis of Denys-Drash syndrome had important consequences for the follow-up and treatment of the patient. The second gonad and the native kidneys were removed due to the increased risk of malignancy. Moreover, the finding of a XY karyotype could result in serious psychic problems. Physicians responsible for the health of adults are confronted more and more often with the consequences of childhood diseases. This case illustrates the necessity to inform such physicians about previously untreatable genetic diseases of childhood so that the adequate medical management of these patients can be guaranteed.

Mitochondrial tRNALeu(UUR) mutation in a patient with steroid-resistant nephrotic syndrome and focal segmental glomerulosclerosis.

BACKGROUND: The heterogeneity of mitochondrial cytopathies is characteristic for this group of disorders, which preferentially affect the muscle and nerve system. The A3243G transition in the tRNA(Leu(UUR)) gene has been associated with slowly progressive forms of focal segmental glomerulosclerosis (FSGS). Here we present a patient who developed a severe nephrotic syndrome during her first pregnancy, which persisted after delivery, and proved resistant to immunosuppressive therapy. A sister of our patient had developed diabetes mellitus. We analysed the DNA for the presence of the mitochondrial DNA (mtDNA) A3243G transition. METHODS: DNA was isolated from peripheral blood leukocytes and urine sediments. Polymerase chain reaction was performed to amplify the mtDNA. Restriction enzyme analysis was used to detect the presence of the A3243G transition. Quantitative analysis of the A3243G mutation was done using the pyrosequencing technique. RESULTS: Quantitative analysis revealed a proportion of mutated mtDNA of 30% in the leukocytes and 68% in the urine sediments of the proband. On further analysis, we also found the transition in the mother, the diabetic sister and the daughter of the proband. CONCLUSION: MtDNA abnormalities can cause a steroid-resistant nephrotic syndrome, histologically characterized by FSGS. Physicians should be especially mindful of mitochondrial abnormalities when hearing loss, diabetes mellitus or neuromuscular disorders are present in the patient or family members.

Nijmegen breakage syndrome: a neuropathological study.

Nijmegen breakage syndrome (NBS) is an autosomal recessive disorder, due to defects in the NBS1 gene and belongs to the DNA repair disorders. We report neuropathological findings of the first ever recognised case of the about 60 described cases of NBS. This patient showed severe microcephaly with a simplified gyral pattern especially in the frontal lobes. There were no signs of a degenerative disease, or of a primary migration disorder. A bulge on top of the corpus callosum, most probably a very large remnant of the involuting striae longitudinales mediales et laterales, was found. This can be considered as an incomplete development of limbic structures. The severe diminishment of neocortical neurones suggests an important role for the NBS1 gene in corticogenesis in man, as suggested earlier in animal studies of other DNA-repair genes.

WT-1 and NPHS2 mutation analysis in patients with non-familial steroid-resistant focal-segmental glomerulosclerosis.

BACKGROUND: Familial forms of steroid-resistant nephrotic syndrome with the histologic findings of focal-segmental glomerulosclerosis have frequently a genetic basis. For the non-familial forms this is still unresolved. PATIENTS AND METHODS: Ten children with non-familial steroid-resistant nephrotic syndrome along with focal-segmental glomerulosclerosis were tested for mutations in the WT-1 and NPHS2 genes. RESULTS: In 1 patient, a mutation in intron 9 of the WT-1 gene and in 1 patient a heterozygous NPHS2 mutation could be detected. Both abnormalities are important for the treatment modalities and prognosis. CONCLUSION: Additional studies will have to provide a solid basis for the recommendation of mutation analysis in non-familial steroid-resistant focal-segmental glomerulosclerosis.

Clinical heterogeneity in patients with mutations in the NDUFS4 gene of mitochondrial complex I.

A comparison of the clinical presentation, disease course and results of laboratory and imaging studies of all patients so far published with a NDUFS4 mutation are presented. This reveals marked clinical heterogeneity, even in patients with the same genotype.

The human complex I NDUFS4 subunit: from gene structure to function and pathology.

Complex I is the first and largest enzyme of the oxidative phosphorylation system. It consists of at least 43 subunits. Recent studies have shown that the NDUFS4 subunit of complex I contributes to the activation of the complex through cAMP dependent phosphorylation of a conserved site (RVS) located at the C-terminal region of this protein. This report focuses on the NDUFS4 subunit. Summarized is the current knowledge of this subunit, from gene structure to function and pathology.