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PURPOSE OF REVIEW The last few years have seen the decoding of the genetic basis for atypical hemolytic uremic syndrome. RECENT FINDINGS Mutations in complement factor H were the first to be associated with atypical hemolytic uremic syndrome. These mutations cluster in the C-terminus of complement factor H. This year has seen the publication of a transgenic mouse model lacking the C-terminus of complement factor H, which spontaneously develops atypical hemolytic uremic syndrome. This mouse model regulated C3 activation in plasma but failed to bind to endothelial cells in an analogous manner to the mutations seen in atypical hemolytic uremic syndrome patients. This year has also seen the emergence of genotype-phenotype correlations in atypical hemolytic uremic syndrome. Patients with membrane cofactor protein mutations have a good prognosis and in those who do develop endstage renal disease, recurrence after transplantation is rare. By contrast, the outcome for patients with complement factor H and complement factor I mutations is poor and the rate of recurrence after transplantation is high. New complement genes associated with atypical hemolytic uremic syndrome have also been described in the past year including factor B, C3, C4b-binding protein, FHR1 and FHR3. SUMMARY Genetic screening is now providing prognostically significant information in predicting survival, renal recovery and transplant outcome. It paves the way for the use of complement inhibitors in the future.

The past decade has seen the identification of mutations in the genes for complement factor H ( CFH ) (1–6), membrane co-factor protein ( MCP ) (7–12), and factor I ( CFI ) (9,13–15) as predisposing factors for the development of atypical hemolytic uremic syndrome (aHUS). With this increased understanding of the genetic basis of aHUS and its implications for patient treatment, particularly transplantation, has come an increasing demand for genetic screening. A full analysis for mutations in all three of these complement proteins is expensive and time-consuming. A rational system is required to optimize the timely delivery of results and to reduce the cost of screening. We suggest some proposals that are based on our own experience with aHUS and our review of the relevant literature. The strategy that we propose (Figure 1) involves an initial screen that is based on protein levels (either serum levels or surface expression). This offers a rapid mechanism to identify the likely gene involved. In those in whom normal levels of complement regulators are found, we propose screening genes on the basis of their order of frequency of mutation detection ( CFH , approximately 30%; MCP , approximately 10%; CFI , 2 to 5%) (15). Furthermore, mutations cluster in certain exons of the genes that code for the protein (60% of CFH mutations cluster in complement control protein modules 19 and 20; 90% of MCP mutations in control protein modules 1 to 4; 60% of CFI mutations in the serine protease domain) (15). By screening these regions first, cost and detection time can be minimized. Figure 1. Flow diagram demonstrating screening strategy in atypical hemolytic uremic syndrome (aHUS). Our suggested screening strategy in aHUS involves a three-tier approach. Level 1 investigations provide a quantitative assessment of protein concentrations by radioimmunodiffusion assay (RIDA) or FACS. …

Atypical hemolytic uremic syndrome (aHUS) is a disease of hemolytic anemia, thrombocytopenia, and renal failure associated with defective alternative pathway (AP) complement control. Previously, we presented a database (www.FH-HUS.org) focusing on aHUS mutations in the Factor H gene (CFH). Here, new aHUS mutations are reported for the complement regulatory proteins Factor H (FH), Factor I (FI), and membrane cofactor protein (MCP). Additional mutations or polymorphisms within CFH have been associated with membranoproliferative glomerulonephritis (MPGN) and age-related macular degeneration (AMD). Accordingly, the database now includes substitutions that predispose to aHUS, MPGN, and AMD. For this, structural models for the domains in MCP and FI were developed using homology modeling. With this new database, patients with mutations in more than one gene can be displayed and interpreted in a coherent manner. The database also includes SNP polymorphisms in CFH, MCP, and IF. There are now a total of 167 genetic alterations, including 100 in CFH, 43 in MCP, and 24 in IF. The mutations characterize clinical outcomes that vary from several AMD-associated polymorphisms to those associated with aHUS, MPGN, or FI deficiency. A consensus short complement regulator (SCR) domain structure facilitated the interpretations of aHUS mutations. Specific locations within this consensus domain often correlate with the occurrence of clinical phenotypes. The AMD Tyr402His polymorphism is structurally located at a hotspot for several aHUS mutations. The database emphasizes the causative role of the alternative pathway of complement in disease and provides a repository of knowledge to assist future diagnosis and novel therapeutic approaches.

Objective Malnutrition is common in patients with chronic renal failure and should be screened for systematically. Subjective global assessment (SGA) is frequently used, but it is time-consuming. The aim of this study was to assess the sensitivity of SGA as a screening tool for malnutrition compared with the measurement of body mass index (BMI) and serum albumin combined with a history of unintentional weight loss. Design This was a cross-sectional study. Setting The study was undertaken in two hospital hemodialysis units. Patients and Intervention A total of 141 patients on hemodialysis were studied. Nutritional assessment was undertaken with a seven-point SGA, measurement of height, weight and serum albumin, and a record of unintentional weight loss. Outcomes Patients were considered to be at risk of malnutrition if any of the following three criteria were met: a serum albumin less than 35 g/L, a BMI less than 18.5, and unintentional weight loss of edema free weight greater than 10% in the past 6 months. A diagnosis of malnutrition was made if the SGA score was between 1 and 5. Results A total of 41 patients had either a serum albumin less than 35 g/L or a BMI less than 18.5 or unintentional weight loss of edema free weight of more than 10% in the past 6 months. Of these 41 patients, 29 had a serum albumin less than 35 g/L, 9 had a BMI less than 18.5, and 15 had unintentional loss of edema free weight greater than 10% in the past 6 months. Thirteen patients were judged by SGA to be mild to moderately malnourished. All 13 were identified by serum albumin, BMI, or weight loss. Conclusions In this study, measurement of SGA did not diagnose malnutrition in any patients in whom this had not already been potentially identified by measurement of serum albumin, BMI, and a history of weight loss. SGA did not therefore increase the sensitivity of nutritional screening in this cohort.

Mutations in complement regulatory proteins predispose to the development of aHUS. Approximately 50% of patients bear a mutation in one of three complement control proteins, factor H, factor I, or membrane cofactor protein (MCP; CD46). Another membrane regulator that is closely related to MCP, decay accelerating factor (DAF; CD55) thus far has shown no association with aHUS and continues to be investigated. The goal of this study was to compare the regulatory profile of MCP and DAF and to assess how alterations in MCP predispose to complement dysregulation. We employed a model system of complement activation on Chinese hamster ovary (CHO) cell transfectants. The four regularly expressed isoforms of MCP and DAF inhibited C3b deposition by the alternative pathway. DAF, but not MCP, inhibited the classical pathway. Most patients with MCP-aHUS are heterozygous and express only 25–50 % of the wild-type protein. We, therefore, analyzed the effect of reduced levels of wild-type MCP and found that cells with lowered expression levels were less efficient in inhibiting alternative pathway activation. Further, a dysfunctional MCP mutant, expressed at normal levels and identified in five patients with aHUS (S206P), failed to protect against C3b amplification on CHO cells, even if expression levels were increased 10-fold. Our results add new information relative to the necessity for appropriate expression levels of MCP and further implicate the alternative pathway in disease processes such as aHUS.

Immune recognition is coupled to powerful proinflammatory effector pathways that must be tightly regulated. The ancient alternative pathway of complement activation is one such proinflammatory pathway. Genetic susceptibility factors have been identified in both regulators and activating components of the alternative pathway that are associated with thrombotic microangiopathies, glomerulonephritides, and chronic conditions featuring debris deposition. These observations indicate that excessive alternative pathway activation promotes thrombosis in the microvasculature and tissue damage during debris accumulation. Intriguingly, distinct genetic changes in factor H (FH), a key regulator of the alternative pathway, are associated with hemolytic uremic syndrome (HUS), membranoproliferative glomerulonephritis (dense deposit disease), or age-related macular degeneration (AMD). A mouse model of HUS designed to mirror human mutations in FH has now been developed, providing new understanding of the molecular pathogenesis of complement-related endothelial disorders.

The hemolytic uremic syndrome is characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia and acute renal failure. There are two general types. One occurs in epidemic form and is diarrheal associated (D+HUS). It has a good prognosis. The second is a rare form known as atypical (aHUS), which may be familial or sporadic, and has a poor prognosis. aHUS is increasingly recognized to be a disease of defective complement regulation, particularly cofactor activity. Mutations in membrane cofactor protein (MCP; CD46) that predispose to the development of aHUS were first identified in 2003. MCP is a membrane-bound complement regulator that acts as a cofactor for the factor I-mediated cleavage of C3b and C4b deposited on host cells. More than 20 different mutations in MCP have now been identified in patients with aHUS. Many of these mutants have been functionally characterized and have helped to define the pathogenic mechanisms leading to aHUS development. Over 75% of the reported mutations cause a reduction in MCP expression, due to homozygous, compound heterozygous or heterozygous mutations. This deficiency of MCP leads to inadequate control of complement activation on endothelial cells after an initiating injury. The remaining MCP mutants are expressed, but demonstrate reduced ligand (C3b/C4b) binding capacity and cofactor activity of MCP. MCP mutations in aHUS demonstrate incomplete penetrance, indicating that additional genetic and environmental factors are required to manifest disease. MCP mutants as a cause of aHUS have a favorable clinical outcome in comparison to patients with factor H (CFH) or factor I (IF) mutations. In 90% of the renal transplants performed in patients with MCP-HUS, there has been no recurrence of the primary disease, whilst >50% of factor I or factor H deficient patients have had a prompt recurrence. This highlights the importance of defining and characterizing the underlying genetic defects in patients with aHUS.

Introduction Thrombotic microangiopathies are a group of diseases presenting as microangiopathic hemolytic anemia, thrombocytopenia and end-organ dysfunction. As the role of the complement system was elucidated in atypical hemolytic uremic syndrome pathogenesis, eculizumab was successfully introduced into clinical practice. We present a large pedigree with multiple individuals carrying a functionally significant novel factor H mutation. We describe the proband’s presentation following a presumed infectious trigger requiring plasma exchange and hemodialysis. Case presentation A 32-year-old Caucasian woman presented with pyrexia and headache lasting one week to our Emergency Department. She gave no history of diarrhea or other symptoms to account for her high temperature. She was not taking any medication. She was pyrexial (38°C), tachycardic (110bpm) and hypertensive (160/110mmHg). Her fundoscopy revealed grade IV hypertensive retinopathy. She had mild pretibial and periorbital edema, with oliguria (450mL/day). She had a pregnancy one year previously, during which she had hypertension, proteinuria and edema, with successful delivery at term. Her mother had died in her early 30s with a clinical picture consistent with thrombotic microangiopathy. Her laboratory evaluation showed microangiopathic hemolytic anemia. After 22 sessions of plasma exchange, her lactate dehydrogenase levels started to climb. As a result, she was classified as plasma resistant and eculizumab therapy was instituted. Her lactate dehydrogenase level and platelet count normalized, and her renal function recovered after three months of dialysis. Conclusions We demonstrate that, even in patients with atypical hemolytic uremic syndrome and prolonged dialysis dependence, recovery of renal function can be seen with eculizumab treatment. We suggest a treatment regime of at least three months prior to evaluation of efficacy.

Age-related macular degeneration (AMD; OMIM #603075) is the most frequent cause of visual impairment in the elderly population, with severe disease affecting nearly 10% of individuals of European descent over the age of 75 years. It is a complex disease in which genetic and environmental factors contribute to susceptibility. Complement factor H (CFH) has recently been identified as a major AMD susceptibility gene, and the Y402H polymorphism has been proposed as the likely causative factor. We genotyped polymorphisms spanning the cluster of CFH and five CFH-related genes on chromosome 1q23 in 173 individuals with severe neovascular AMD and 170 elderly controls with no signs of AMD. Detailed analysis showed a common haplotype associated with decreased risk of AMD that was present on 20% of chromosomes of controls and 8% of chromosomes of individuals with AMD. We found that this haplotype carried a deletion of CFHR1 and CFHR3, and the proteins encoded by these genes were absent in serum of homozygotes. The protective effect of the deletion haplotype cannot be attributed to linkage disequilibrium with Y402H and was replicated in an independent sample.

Familial hemolytic uremic syndrome (HUS) was first described in 1956; both autosomal dominant and recessive forms of inheritance have been reported. The chapter discusses three pieces of evidence which suggested that complement genes apart from the gene for factor H were involved in the pathogenesis of atypical HUS. Structurally, membrane cofactor protein (MCP) consists of four alternatively spliced isoforms that coexist on most cells. The extracellular domain is composed of four control protein modules (CCPs). Western blot, flow cytometry, cell surface labeling, and pulse-chase analysis all showed that the mutant protein was retained intracellularly. Noris et al. described a family in which two siblings were affected by HUS. Mutation screening in both revealed a heterozygous 2-bp deletion in MCP exon 7, which encodes CCP4. The functional effect of this mutation is similar to the deletion mutation and results in half of the normal level of cell surface expression of MCP. The two techniques most frequently used for mutation scanning are denaturing high-performance liquid chromatography (DHPLC) and single-strand conformation polymorphism (SSCP). DHPLC is based on heteroduplex analysis in which mutant and wild-type sequences present in a PCR product are heated and allowed to reanneal slowly. This results in the formation of two heteroduplexes and two homoduplexes. MLPA (multiplex ligationdependent probe amplification) is a relatively new method for detecting deletions and duplications in a simple two-stage procedure and gives dosage information for up to 45 exons in one test.

Mutations in the genes for three complement regulators-complement factor H (CFH), membrane cofactor protein (MCP), and factor I (IF)-have now been described in patients with atypical HUS. The functional effects of these mutations have been studied in detail and have been shown to affect secretion, expression, and regulatory function. Genotype-phenotype correlations have shown that the majority of patients with CFH, MCP, and FI mutations develop end-stage renal failure. The outcome of transplantation is poor in patients known to have either a CFH or FI mutation, with approximately 80% of patients losing the graft to recurrent disease within 2 years. In contrast, patients known to have only an MCP mutation have a satisfactory transplantation outcome. This is expected because MCP is a transmembrane regulator and allografts will therefore be protected by wild-type MCP. Combined liver/kidney transplantation for patients known to have a CFH mutation has not been successful to date. There is optimism that in the future, targeted complement inhibitors will be of major therapeutic benefit in this condition.

● Hemolytic uremic syndrome not associated with diarrhea (diarrhea negative, atypical) is less common than the diarrhea-positive typical form, but frequently results in end-stage renal failure. Although there are anecdotal cases of successful treatment with fresh frozen plasma alone, the value of this treatment compared with plasma exchange (PE) is difficult to assess. We describe monozygotic female twins who presented at 5 years of age with factor H‐related (c.3572 > T; Ser1191Leu) atypical hemolytic uremic syndrome within months of each other. In the first twin to present, 10 sessions of PE with fresh frozen plasma replacement (40 mL/kg) resulted in resolution of hemolysis and improvement in plasma creatinine level (1.9 to 1.5 mg/dL [166 to 137 mol/L]). Subsequently, 17 infusions of fresh frozen plasma were administered during a 4-month period for recurrent thrombocytopenia. However, within 4 months, plasma creatinine level increased to 5.1 mg/dL (450 mol/L), necessitating peritoneal dialysis. When the second twin presented with the same disease, an extended PE regimen was instituted. After 10 daily sessions, PE was continued once every 2 weeks. Two recurrences were treated successfully with daily PE for 7 days. After 44 months of follow-up, kidney function is normal (plasma creatinine, 0.6 mg/dL [53 mol/L]; creatinine clearance, 119 mL/min/1.73 m 2 [1.98 mL/s/1.73 m 2 ]) on maintenance PE therapy. In conclusion, the response to treatment of these monozygotic twins suggests that long-term PE may have benefits over plasma infusion alone. Am J Kidney Dis 47:E27-E30. © 2005 by the National Kidney Foundation, Inc.

Mutations in the plasma complement regulator factor H (CFH) and the transmembrane complement regulator membrane co-factor protein (MCP) have been shown to predispose to atypical hemolytic uremic syndrome (HUS). Both of these proteins act as co-factors for complement factor I (IF). IF is a highly specific serine protease that cleaves the alpha-chains of C3b and C4b and thus downregulates activation of both the classical and the alternative complement pathways. This study looked for IF mutations in a panel of 76 patients with HUS. Mutations were detected in two patients, both of whom had reduced serum IF levels. A heterozygous bp change, c.463 GA, which results in a premature stop codon (W127X), was found in one, and in the other, a heterozygous single base pair deletion in exon 7 (del 922C) was detected. Both patients had a history of recurrent HUS after transplantation. This is in accordance with the high rate of recurrence in patients with CFH mutations. Patients who are reported to have mutations in MCP, by contrast, do not have recurrence after transplantation. As with CFH- and MCP-associated HUS, there was incomplete penetrance in the family of one of the affected individuals. This study provides further evidence that atypical HUS is a disease of complement dysregulation.

Background: In both familial and sporadic atypical haemolytic-uraemic syndrome (aHUS), mutations have been reported in regulators of the alternative complement pathway including factor H (CFH), membrane cofactor protein (MCP), and the serine protease factor I (IF). A characteristic feature of both MCP and CFH associated HUS is reduced penetrance and variable inheritance; one possible explanation for this is that functional changes in complement proteins act as modifiers. Objective: To examine single nucleotide polymorphisms in both CFH and MCP genes in two large cohorts of HUS patients (Newcastle and Paris). Results: In both cohorts there was an association with HUS for both CFH and MCP alleles. CFH and MCP haplotypes were also significantly different in HUS patients compared with controls. Conclusions: This study suggests that there are naturally occurring susceptibility factors in CFH and MCP for the development of atypical HUS.

Background The anabolic effects of insulin are well recognized but the mechanism by which insulin decreases muscle protein degradation in human is unclear. However, in a variety of catabolic conditions it is believed to be changes in the activity of the ATP-dependent ubiquitin proteolytic pathway that are responsible for changes in protein degradation in skeletal muscle. The aim of this study was to test the hypothesis that insulin regulates the ATP-dependent ubiquitin proteolytic pathway in human muscle. Material and methods The effects of insulin and acidosis on protein degradation were measured in human myocytes using L-[14C]phenylalanine. The effect of insulin on the activity of the ATP-dependent ubiquitin pathway was assessed from the mRNA expression of ubiquitin and the ubiquitin-conjugating enzyme E214k in human myocytes. Results and conclusions Coincubation of human myocytes with 100 nM of insulin was associated with a significant reduction in protein degradation. Metabolic acidosis is known to increase skeletal muscle protein degradation rates, and in our experiments protein degradation at a pH of 7·0 was significantly higher than pH 7·35. Eight-hour exposure to 100 nM of insulin resulted in a significant reduction in the expression of E214k but no change in the expression of ubiquitin. Conclusions In human muscle we have demonstrated regulation by insulin of the ATP-dependent ubiquitin pathway at the level of ubiquitin conjugation.

Tremendous advances in our understanding of the thrombotic microangiopathies (TMAs) have revealed distinct disease mechanisms within this heterogeneous group of diseases. As a direct result of this knowledge, both children and adults with complement-mediated TMA now enjoy higher expectations for long-term health. In this update on atypical hemolytic uremic syndrome, we review the clinical characteristics; the genetic and acquired drivers of disease; the broad spectrum of environmental triggers; and current diagnosis and treatment options. Many questions remain to be addressed if additional improvements in patient care and outcome are to be achieved in the coming decade.

Effects of feeding on albumin synthesis in hypoalbuminemic hemodialysis patients.BackgroundHypoalbuminemia is a powerful predictor of morbidity and mortality in hemodialysis (HD) patients and results from a reduction in albumin synthesis. It is not known if this is associated with any impairment of the normal response to feeding.MethodsProtein turnover and albumin synthesis were measured in the fasting and fed state using a primed constant infusion of L-[1-13C]leucine in seven hypoalbuminemic (albumin ≤ 36 g/L) HD patients (HHD), seven normoalbuminemic (albumin ≥ 40 g/L) HD patients (NHD) and nine age-matched normal controls.ResultsThe increase in albumin synthesis on feeding was impaired in HHD patients (fasting 15.0 ± 1.5 vs. fed 17.7 ± 2.9%, P = NS) compared to NHD (fasting 13.7 ± 0.9 vs. fed 17.4 ± 1.0%, P < 0.05) and controls (fasting 12.9 ± 0.6 vs. fed 15.2 ± 0.6%, P < 0.05). In addition, body mass index and percent body fat were significantly (P < 0.05) lower in HHD (20.8 ± 1.3 kg/m2, 23.4 ± 2.0%) than NHD (26.7 ± 1.3 kg/m2, 33.1 ± 3.2%) or controls (26.2 ± 1.1 kg/m2, 32.6 ± 1.8%). There was no difference in dietary protein or energy intake in the three groups.ConclusionsThere are differences of body composition and protein metabolism in HHD patients that may be related to an impaired metabolic response to feeding.

Background In chronic renal failure, metabolic acidosis is associated with increased whole body protein degradation. In rats this effect of acidosis occurs in skeletal muscle and is associated with increased ubiquitin mRNA expression. This has not been demonstrated in humans. Materials and methods Six patients with chronic renal failure and acidosis underwent muscle biopsy before and after 1 month's treatment with sodium bicarbonate. RNA was extracted from the biopsy, and the expression of the genes for ubiquitin and the proteasome component, C2, were measured by Northern blotting. Results and conclusions There was no significant difference in the expression of ubiquitin or C2 after bicarbonate treatment. This is contrast with results from animal models of acidosis and some other catabolic conditions in humans. This may reflect the complexity of the ubiquitin-dependent pathway, and it may be that changes in ubiquitin expression are only seen with more severe and/or acute changes in pH.

Solitary functioning kidney and diverse genital tract malformations associated with hepatocyte nuclear factor-1β mutations. Background Renal tract malformations are, on occasion, associated with uterine malformations. The transcription factor hepatocyte nuclear factor (HNF)-1β is expressed from the earliest stages of development of the Wolffian duct, the mesonephros and metanephros, and the Mullerian ducts in the mouse. In adult mice HNF-1β is expressed in the kidney tubules, collecting ducts, and in the oviducts and uterus in the female (Mullerian duct derivatives) and in the epididymis, vas deferens and seminal vesicles (Wolffian duct derivatives) in the male. HNF-1β mutations have been reported in two families where affected members have renal abnormalities, female genital tract malformations and early-onset diabetes. Renal and uterine abnormalities have not been described in families without early-onset diabetes. Methods We sequenced the HNF-1β gene in nine subjects with renal abnormalities and a personal or family history of female genital tract malformations, but no history of diabetes. Results Two families were identified with novel HNF-1β mutations: a missense mutation in exon 2 with conversion of serine to proline at codon 151 (S151P) and a frameshift mutation in exon 3 with a 1 base pair deletion at codon 243 (Q243fsdelC). The S151P mutation proband has cystic kidneys and uterus didelphys. Her affected second son has renal cysts and hypospadias. The Q243fsdelC proband has a single functioning kidney and her two children have renal dysplasia. Histology in one child shows cystic dysplasia with a lack of glomeruli. The proband's sister is a mutation carrier and has a bicornuate uterus. Diabetes is not a feature in either family. Conclusions This study confirms an association between HNF-1β mutations and renal and Mullerian anomalies. The hypospadias may be coincidental. This study describes the first HNF-1β mutations that are associated with a single functioning kidney and the absence of diabetes. This study further reinforces the variability of the renal and non-renal phenotypes associated with HNF-1β mutations.

Muscle wasting is a common and prominent feature of advanced cancer, including lung cancer. Evidence from animal experiments suggests that accelerated proteolysis via the ubiquitin-proteasome pathway is the primary cause of cancer-related cachexia. However, there are few data on the role of this pathway in determining muscle wasting in human cancer. The present study was designed to measure whether skeletal muscle gene expression of components of the ubiquitin-proteasome pathway and/or the lysosomal proteolytic pathway was increased in patients with early lung cancer. A total of 36 patients with lung cancer referred for curative resection and 10 control subjects had biopsies of latissimus dorsi muscle taken at operation. mRNA levels of four components of the ubiquitin-proteasome pathway, i.e. polyubiquitin, C2α proteasome subunit, 14kDa ubiquitin-carrier protein and ubiquitin-activating protein, and of two lysosomal proteolytic enzymes, i.e. cathepsin B and cathepsin D, were measured using quantitative Northern blotting. mRNA levels for cathepsin B, but not for components of the ubiquitin-proteasome pathway, were higher in patients with cancer compared with controls (P = 0.01). Among lung cancer patients, cathepsin B mRNA levels correlated with fat-free mass index (r =-0.57, P = 0.003) and tumour stage (rs = 0.45, P = 0.03), and were higher in smokers (P = 0.04). Thus gene expression of the lysosomal protease cathepsin B is increased in the skeletal muscle of patients with early lung cancer, and the strong inverse relationship with fat-free mass suggests that cathepsin B may have a role in inducing muscle wasting in the early stages of lung cancer.

Inherited abnormalities of complement are found in ∼60% of patients with atypical haemolytic uraemic syndrome (aHUS). Such abnormalities are not fully penetrant. In this study, we have estimated the penetrance of the disease in three families with a CFH mutation (c.3643CG; p. Arg1215Gly) in whom a common lineage is probable. 25 individuals have been affected with aHUS with three peaks of incidence-early childhood (n=6), early adulthood (n=11) and late adulthood (n=8). Eighteen individuals who have not developed aHUS carry the mutation.We estimated penetrance at the ages of 4, 27, 60 and 70 years as both a binary and a survival trait using MLINK and Mendel. We genotyped susceptibility factors in CFH, CD46 and CFHR1 in affected and unaffected carriers.We found that the estimates of penetrance at the age of 4 years ranged from0.01 to 0.10, at the age of 27 years from 0.16 to 0.29, at the age of 60 years from 0.39 to 0.51 and at the age of 70 years from 0.44 to 0.64. We found that the CFH haplotype on the allele not carrying the CFH mutation had a significant effect on disease penetrance. In this family, we did not find that the CD46 haplotypes had a significant effect on penetrance.

In order to understand how acidosis might predispose to loss of lean body mass it is important to recognise that body protein is in a dynamic state with a daily turnover of approximately 300 g of protein in a 60 kg man. This is significantly greater than the daily protein intake at a level of 1 g.kg-1.day-1. Loss of lean body mass occurs when the balance between whole body protein synthesis and breakdown is negative. Measurement of whole body protein turnover is possible using either boluses or primed constant infusions of isotopically labelled amino acids. Previously, a variety of in vitro and in vivo animal studies have shown that acidosis increases protein degradation and amino acid oxidation. Several research groups including our own have used amino acid tracer techniques to examine whether protein degradation is increased in vivo in human subjects with acidosis and chronic renal failure. The results from these studies have shown a remarkable concordance with increased protein degradation in all groups of patients studied. However, the results for protein synthesis have been more difficult to interpret, with only a few studies directly measuring the effects of acidosis on amino acid incorporation into protein.

Background . Nutritional status is known to play an important role in determining outcome after many types of operations but its importance relative to nonnutritional indices in patients undergoing an operation for lung cancer is unclear. Methods . Detailed nutritional and nonnutritional assessment of 52 patients undergoing surgical resection of lung cancer was performed. The frequency of postoperative complications and length of intercostal drainage time were recorded, and the relation between preoperative indices and postoperative outcome was assessed. Results . Patients who died or needed reventilation had poorer nutritional status, worse lung function, and lower maximum expiratory pressures than those who did not. Using multiple logistic regression, the best model (R 2 = 0.39) to predict death combined operation type, preoperative carbon monoxide transfer factor (% predicted), and maximum expiratory pressure (% predicted). Operation type and the fat-free mass index (FFMI) alone were only slightly less informative (R 2 = 0.35). For reventilation the best model (R 2 = 0.80) combined operation type, body mass index (BMI), and maximum expiratory pressure (% predicted). Intercostal drainage time after lobectomy was significantly related only to preoperative lymphocyte count ( p = 0.004) and subjective global assessment score ( p = 0.02). Conclusions . Impaired nutrition is an important predictor of death and the need for reventilation after an operation for lung cancer, and the selection of patients for lung resection might be improved by measuring simple nutritional indices such as BMI and the FFMI.

Sirs, The oldest of three sisters, two of whom are monozygous twins, presenting all with atypical hemolytic uremic syndrome (aHUS) associated with a CFH mutation, was referred at the age of 3 years to the Emma Children’s Hospital/Academic Medical Centre of Amsterdam (Fig. 1) [1, 2]. She never recovered renal function and commenced peritoneal dialysis. Bilateral nephrectomy was performed 1 year later because of hypertension. She lost two transplants by recurrence, one immediately posttransplantation and the other one 2 months posttransplant despite preventive plasma exchanges (PEs) contemporary to frequency reduction of PE. From the age of 15 years, she began to experience transient sensory and motor symptoms on both sides of her body associated with low blood pressure (BP) during hemodialysis. Magnetic resonance angiogram (MRA) showed severe stenoses of both middle and both anterior cerebral arteries (Fig. 2a) (partial report in [3]). She did not present any additional risk factors for developing arteriosclerosis (such as long-duration hypertension, diabetes, uncontrolled hyperparathyroidism). No arterial calcification and no left ventricular hypertrophy were shown. Fig. 1 Clinical course in patient and her twin sisters Fig. 2 Three-Tesla magnetic resonance images (MRIs) of patient 2 (a, b) and her sister (c). Coronal 3D time-of flight (TOF) MRA maximum intensity projection (MIP) (a) image of patient at the age of 15 years demonstrates (near) occlusion of the M1 segment of ... At the age of 17 years, the patient was transplanted for the third time under pre- and postoperative prophylactic PEs [1, 2]. Postoperatively, she developed infarcts in the right frontal and frontoparietal regions (Fig. 2b). She recovered almost completely. Ten months after transplantation, the child developed bronchospasm and hypotension during PE. For this reason, she was switched to eculizumab [2]. Under this treatment, she presented no HUS recurrence, and renal function remained stable (plasma creatinine 120 μmol/L) 16 months after PE discontinuation. The first of her twin sisters (twin 1) developed aHUS at the age of 5.3 years. She required chronic dialysis despite initial daily PE for 10 days and three intermittent courses of fresh frozen plasma (FFP) infusions. Two years later, she received a cadaver renal transplant under PE prophylaxis. At 7.5 years follow-up, the graft function is satisfactory (serum creatinine 137 μmol). The second twin (twin 2) presented aHUS at the age of 5.8 years (Fig. 1) [1]. She was treated immediately with daily PE and, following remission, with one PE every 2 weeks to this time. At 9.5 years after HUS onset, native renal function (serum creatinine 49 μmol/L) was normal. MRA showed normal cerebral vasculature in both twins at age 14 years (Fig. 2c). Contrary to their older sister with cerebral artery stenoses who was treated by prophylactic PE for 2 months only, the twin sisters received prophylactic PE without interruption for, respectively, 7.5 (twin 1) and 9 (twin 2) years. Although brain ischemia sometimes resulting in cerebral infarct is observed in aHUS, stenosis of large vessels has been reported in aHUS only once—in a child presenting with a Lys350Asp gain of function CFB mutation [4]. Of note, this patient, as ours, was dialyzed for long periods from the age of 4 months. At the age of 10 years, she started having episodes of bilateral hemiparesis during hemodialysis in relation with multiple stenoses of cerebral arteries. Stenoses of large arteries have never been reported as a complication of renal replacement therapy (RRT) in children [5]. Chronic continuous complement dysregulation might contribute to vascular lesions. Indeed complement activation occurs both in human and experimental atherosclerosis, and the deposition of C5b-9 correlates with disease state [6]. Our patient and the patient reported recently by Loirat et al. [4] suggest that aHUS with complement dysregulation, a disease of microvascularization, may also involve large arteries, especially when patients have to face long periods of dialysis when plasma therapy is not used. The latter reports also raise the question of preventing vascular lesions by avoiding complement system disorders. This emphasizes the importance of including patients at an early stage in specific programs of kidney transplantation using preventive plasma therapy or combined liver transplantation. Inhibition of the complement system by anti-C5 antibody that is actually under investigation might be valuable for this purpose in the future [2].

Primary vesicoureteric reflux (VUR) affects 1%-2% of whites, and reflux nephropathy (RN) causes up to 15% of end-stage renal failure in children and adults. There is a 30-50-fold increased incidence of WR in first-degree relatives of probands, compared with the general population. We report the results of the first genomewide search of VUR and RN; we studied seven European families whose members exhibit apparently dominant inheritance. We initially typed 387 polymorphic markers spaced, on average, at 10 cM throughout the genome; we used the GENEHUNTER program to provide parametric and nonparametric linkage analyses of affected individuals. The most positive locus spanned 20 cM on 1p13 between GATA176C01 and D1S1653 and had a nonparametric LOD score (NPL) of 5.76 (P = .0002) and a parametric LOD score of 3.16. Saturation with markers at 1-cM intervals increased the NPL to 5.94 (P = .00009). Hence, WR maps to a locus on chromosome 1. There was evidence of genetic heterogeneity at the chromosome 1 locus, and 12 additional loci were identified genomewide, with P < .05. No significant linkage was found to Gp, where a renal and ureteric malformation locus has been reported, or to PAX2, mutations of which cause WR in renal-coloboma syndrome. Our results support the hypothesis that WR is a genetic disorder.

the first, aVected individuals, particularly siblings usually residing in regions geographically related to outBackground. In a recent study of three families we have found that inherited haemolytic uraemic syn- breaks of HUS, suVer disease within days or weeks of each other and temporally related to the outbreak. It drome (HUS ) maps to a region of chromosome 1q containing the gene for complement factor H. In one is likely that an infectious agent is responsible. The second familial form of HUS occurs at diVerent times of these families and also in a case of sporadic DHUS, we have identified mutations in the factor H implying an inherited predisposition. In this form prognosis is poor, mortality is high (often over 50%) gene. A further family with inherited HUS has therefore been investigated. and recurrence is not uncommon. In a recent study of three families, we have found that inherited HUS maps Methods. DNA extracted from the family members and DNA extracted from archival post-mortem mat- to a region of chromosome 1q containing the gene for complement factor H. In one of these families, and erial from a deceased family member, was studied. Review of renal biopsies and study of complement also in a case of sporadic D-HUS, we have identified mutations in the factor H gene [2]. components was also undertaken. Results. This family demonstrates an inherited defi- We now present a further family in which an inherited deficiency of complement factor H is associated ciency of complement factor H. Non-diarrhoeal HUS has aVected at least two family members with half with HUS. normal levels of factor H. Conclusion. These findings represent further evidence of the association between factor H dysfunction and Family pedigrees and case histories (Figure 1) HUS. II-4 (Index case)

Genetic studies into inherited and sporadic hemolytic uremic syndrome. Hemolytic uremic syndrome (HUS) in adults carries a high morbidity and mortality, and its cause remains unknown despite many theories. Although familial HUS is rare, it affords a unique opportunity to elucidate underlying mechanisms that may have relevance to acquired HUS. We have undertaken a genetic linkage study based on a candidate gene approach. A common area bounded by the markers D1S212 and D1S306, a distance of 26 cM located at 1q32 segregated with the disease (Z max 3.94). We demonstrate that the gene for factor H lies within the region. Subsequent mutation analysis of the factor H gene has revealed two mutations in patients with HUS. In an individual with the sporadic/relapsing form of the disease we have found a mutation comprising a deletion, subsequent frame shift and premature stop codon leading to half normal levels of serum factor H. In one of the three families there is a point mutation in exon 20 causing an arginine to glycine change, which is likely to alter structure and hence function of the factor H protein. Factor H is a major plasma protein that plays a critical regulatory role in the alternative pathway of complement activation. In light of these findings and previous reports of HUS in patients with factor H deficiency, we postulate that abnormalities of factor H may be involved in the etiology of HUS.

Correction of acidosis in hemodialysis patients increases the sensitivity of the parathyroid glands to calcium. In this study, the parathyroid response to the correction of acidosis in eight hemodialysis patients was determined by performing dynamic assessment of parathyroid function before and after the correction of acidosis. The parathyroid response to intravenous calcitriol before and after the correction of acidosis was also assessed. After optimal correction of acidosis, there were no significant changes in blood pH, ionized calcium, phosphate, or alkaline phosphatase values, but the level of venous total CO2 increased significantly. Parathyroid hormone/ionized calcium curves were displaced downward after correction of acidosis, but not after the administration of intravenous calcitriol. The correction of metabolic acidosis in hemodialysis patients with secondary hyperparathyroidism can suppress parathyroid hormone secretion by increasing the sensitivity of the parathyroid glands to ionized calcium.

Correction of acidosis in hemodialysis (HD) decreases protein degradation. The effect of the correction of chronic metabolic acidosis in chronic renal failure patients treated with HD was determined from the kinetics of infused L-[1-(13)C]leucine. Six HD patients were studied before (acid) and after (bicarbonate) correction of acidosis (pH: acid 7.36 +/- 0.01, bicarbonate 7.40 +/- 0.01, P0.005). Leucine appearance from body protein (PD) and leucine disappearance into body protein (PS) decreased significantly with correction of acidosis (PD: acid 180.6 +/- 7.3, bicarbonate 130.9 +/- 7.2 mumol.kg-1.h-1, P0.005; PS: acid 172.3 +/- 6.8, bicarbonate 122.0 +/- 6.8 mumol.kg-1.h-1, P0.005). There was no significant change in leucine oxidation or plasma amino acid concentrations. These results demonstrate that optimal correction of acidosis in HD is beneficial in terms of protein turnover and may improve long-term nutritional status in HD.

Summary Hemolytic uremic syndrome (HUS) is a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. The atypical form of HUS is a disease characterized by complement overactivation. Inherited defects in complement genes and acquired autoantibodies against complement regulatory proteins have been described. Incomplete penetrance of mutations in all predisposing genes is reported, suggesting that a precipitating event or trigger is required to unmask the complement regulatory deficiency. The underlying genetic defect predicts the prognosis both in native kidneys and after renal transplantation. The successful trials of the complement inhibitor eculizumab in the treatment of atypical HUS will revolutionize disease management.

Item does not contain fulltext BACKGROUND: Atypical hemolytic-uremic syndrome is a genetic, life-threatening, chronic disease of complement-mediated thrombotic microangiopathy. Plasma exchange or infusion may transiently maintain normal levels of hematologic measures but does not treat the underlying systemic disease. METHODS: We conducted two prospective phase 2 trials in which patients with atypical hemolytic-uremic syndrome who were 12 years of age or older received eculizumab for 26 weeks and during long-term extension phases. Patients with low platelet counts and renal damage (in trial 1) and those with renal damage but no decrease in the platelet count of more than 25% for at least 8 weeks during plasma exchange or infusion (in trial 2) were recruited. The primary end points included a change in the platelet count (in trial 1) and thrombotic microangiopathy event-free status (no decrease in the platelet count of >25%, no plasma exchange or infusion, and no initiation of dialysis) (in trial 2). RESULTS: A total of 37 patients (17 in trial 1 and 20 in trial 2) received eculizumab for a median of 64 and 62 weeks, respectively. Eculizumab resulted in increases in the platelet count; in trial 1, the mean increase in the count from baseline to week 26 was 73x10(9) per liter (P

In normal humans and in patients with chronic renal failure (CRF), acidosis increases whole-body protein degradation. Correction of acidosis reduces protein degradation. The mechanisms underlying these changes in protein metabolism are unclear. However, one possibility is that dietary protein intake is reduced in acidosis and that this causes increased protein degradation. This possibility has not been tested. In this study the effects of acidosis on protein intake in patients with CRF have been assessed using 7-day weighed dietary inventories in the acidotic state (venous bicarbonate 15.6 +/- 1.0 mmol/L) and following treatment with oral sodium bicarbonate (venous bicarbonate 21.0 +/- 1.4 mmol/L). Protein intake was also derived from urinary nitrogen excretion. There was no significant difference in protein intake calculated from dietary records (1.0 +/- 0.09 g/kg/d v 1.06 +/- 0.1 g/ kg/d) or calculated from urinary nitrogen (1.13 +/- 0.07 g/kg/d v 1.06 +/- 0.06 g/kg/d) between the untreated and bicarbonate-treated states in eight patients with CRF. We conclude that acidosis in CRF patients does not affect dietary protein intake and that dietary changes therefore do not contribute significantly to the changes in protein metabolism seen in acidosis.

Background. Termination of renal replacement therapy (RRT) is common in North America and Australia but is considered to be rare in Europe. Methods. In order to review the phenomenon of RRT termination in all patients treated in Newcastle upon Tyne between 1964 and 1993 a retrospective study of clinical case notes was undertaken. In all RRT patients sex, age at start of RRT, renal diagnosis and history of RRT were recorded. In addition, mortality data and marital and residential status were recorded in all patients who died, and Karnofsky index, bodyweight, complications, history of bereavement, place of death, overall survival, survival after withdrawal of treatment, other medical problems, higher mental function and surgical history in all patients stopping treatment. Results. 1639 patients started RRT between 1964 and September 1993 inclusive. Eighty-eight patients were identified in whom death was a result of treatment being stopped (17% of all deaths). The first was in 1985. In these patients, age was greater (62 vs 47 years, P

Atypical haemolytic uraemic syndrome (aHUS) is caused by dysregulated complement activation. A humanised anti-C5 monoclonal antibody has recently become available for treatment of this conditionWe present the first description of an infant with an activating mutation of complement factor B successfully treated with eculizumab. On standard doses she had evidence of ongoing C5 cleavage despite a good clinical response.Eculizumab is effective therapy for aHUS associated with factor B mutations, but recommended doses may not be adequate for all patients.

We present three cases of organ transplantation for atypical haemolytic uraemic syndrome secondary to complement factor H mutation: one isolated renal transplant; one previously reported isolated liver transplant; and one combined liver and kidney transplant. All three patients were treated prior to the licensing of eculizumab for this condition, and all have had favourable outcomes with maintenance of graft function for years following transplantation. We discuss the evolution of transplantation therapy for aHUS over the last two decades. Transplantation decision-making in aHUS has evolved over this time with expanding knowledge of pathophysiology and genetics, alongside refined plasma exchange and anticoagulation protocols and improved centre experience. Our cases demonstrate how individual patient factors within this heterogeneous condition also underlie transplantation decisions and outcomes. Whilst our cases demonstrate that transplantation in aHUS can be a successful long-term treatment providing good quality of life, worldwide experience has proven that most curative treatment for aHUS strategies represents significant risks. Whether new pharmacotherapies such as eculizumab will alter this risk is yet to be determined.

A questionnaire-based survey of the practice of renal dietitians in the UK has been undertaken. The questionnaire was designed to examine three areas: nutritional practice, nutritional assessment and nutritional support. There was a response rate of 86% (61/71). Staffing levels ranged from 0 to 3.0 (median 1.0) whole time equivalents (WTE). The ratio of dialysis patients to dietitians ranged from 39 to 244 per WTE (median 134). Nutrition was perceived to be of low priority in four units, of medium priority in 25 and of high priority in 32. Dietary prescription was specified in three ways: by medical staff (33/61), as per unit policy (16/61) and as decided by the dietitian (54/61). Dietary protein prescription ranged from 0.5 to 1.0 g/kg/day (mean 0.71) in pre-dialysis patients, from 1.0 to 1.4 g/kg/day (mean 1.08) in haemodialysis (HD) patients and from 1.0 to 1.5 g/kg/day (mean 1.3) in CAPD. The prevalence of malnutrition in all three groups of patients was estimated to be less than 30% by the majority of dietitians. Weight and height (56/61), body mass index (53/61) and serum albumin (58/61) were used most frequently to assess nutritional status. Urea kinetic modelling was used infrequently (HD 21, CAPD 4, pre-dialysis 1). Nutritional audit was performed in only 14 units. This study suggests that the identification and treatment of malnutrition in UK renal units is of a low priority at present. This needs to be reversed and dietitian's should be responsible for this role.

Highlights ► Hypothesis tested: common sequence variants in complement are associated with aHUS. ► SNPs in complement genes were genotyped in two independent aHUS cohorts. ► Only SNPs within CFH, CD46 and the CFHRs showed a replicable association with aHUS. ► Complement regulators variability has the main role in determining the disease., It is well established that common genetic variants in CFH, CD46 and the CFHRs are additional risk factors for the development of aHUS. To examine the hypothesis that common variants in other complement genes have a similar effect we genotyped 501 SNPs in 47 complement genes in 94 aHUS patients from Newcastle, 126 aHUS patients from Paris, 374 UK controls and 165 French controls. We replicated the associations in CFH, CD46 and the CFHRs but found no association with any other complement gene. The strongest associations replicated in both cohorts were found for four SNPs within CD46 (p-value

An in vivo cross-over study has investigated plasma and cellular levels of IL-1 (IL-1 alpha IL-1 beta and IL-1Ra) when using Cuprophan (C) and cellulose triacetate (CTA) membranes to assess the roles of complement activation and dialysate endotoxin content in the induction of cytokines during the dialysis procedure. The mean C5a level during Cuprophan dialysis was 29.9 +/- 0.63 ng/ml (Mean +/- SEM), while for the cellulose triacetate dialysis was 3.09 +/- 0.7 ng/ml. The endotoxin content of the dialysate was 0.31 +/- 0.34 EU/ml and 0.68 +/- 1.39 EU/ml. These two factors failed to produce measurable changes in plasma or cellular IL-1 alpha and IL-1 beta levels during treatment. The plasma IL-1Ra levels predialysis were similar to those for normal controls (CTA 769 +/- 156 ng/ml, C739 +/- 93, normal controls 635 +/- 33) with a considerable day to day variation. A membrane independent fall in plasma IL-1Ra at 15 minutes was noted (CTA 420 +/- 92 ng/ml, C 503 +/- 139) with a return to pre-dialysis levels by the end of treatment. Cellular IL-1Ra levels pre-dialysis were similar to the normal group--(CTA 1904 +/- 291 ng/ml, C 1564 +/- 292 and normal control 1971 +/- 368). However, on average, the values when using cellulose triacetate were 655 +/- 623 pg/ml higher than for Cuprophan (p = 0.03). These findings indicate that the measurement of plasma cytokine levels is of limited use in the study of cytokine induction by the haemodialysis procedure and that IL-1Ra may be a better indicator of the host response to cytokine stimuli during treatment. However, a considerable inter-patient and intra-treatment variation is present and further studies are required to elucidate the factors involved.

Systemic lupus erythematosus (SLE), a complex polygenic autoimmune disease, is associated with increased complement activation. Variants of genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) within the chromosome 1q32 locus linked to SLE, have been associated with multiple human diseases and may contribute to dysregulated complement activation predisposing to SLE. We assessed 60 SNPs covering the CFH-CFHRs region for association with SLE in 15,864 case-control subjects derived from four ethnic groups. Significant allelic associations with SLE were detected in European Americans (EA) and African Americans (AA), which could be attributed to an intronic CFH SNP (rs6677604, in intron 11, P meta = 6.6×10−8, OR = 1.18) and an intergenic SNP between CFHR1 and CFHR4 (rs16840639, P meta = 2.9×10−7, OR = 1.17) rather than to previously identified disease-associated CFH exonic SNPs, including I62V, Y402H, A474A, and D936E. In addition, allelic association of rs6677604 with SLE was subsequently confirmed in Asians (AS). Haplotype analysis revealed that the underlying causal variant, tagged by rs6677604 and rs16840639, was localized to a ∼146 kb block extending from intron 9 of CFH to downstream of CFHR1. Within this block, the deletion of CFHR3 and CFHR1 (CFHR3-1Δ), a likely causal variant measured using multiplex ligation-dependent probe amplification, was tagged by rs6677604 in EA and AS and rs16840639 in AA, respectively. Deduced from genotypic associations of tag SNPs in EA, AA, and AS, homozygous deletion of CFHR3-1Δ (P meta = 3.2×10−7, OR = 1.47) conferred a higher risk of SLE than heterozygous deletion (P meta = 3.5×10−4, OR = 1.14). These results suggested that the CFHR3-1Δ deletion within the SLE-associated block, but not the previously described exonic SNPs of CFH, might contribute to the development of SLE in EA, AA, and AS, providing new insights into the role of complement regulators in the pathogenesis of SLE., Author Summary Systemic lupus erythematosus (SLE) is a complex autoimmune disease, associated with increased complement activation. Previous studies have provided evidence for the presence of SLE susceptibility gene(s) in the chromosome 1q31-32 locus. Within 1q32, genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) may contribute to the development of SLE, because genetic variants of these genes impair complement regulation and predispose to various human diseases. In this study, we tested association of genetic variants in the region containing CFH and CFHRs with SLE. We identified genetic variants predisposing to SLE in European American, African American, and Asian populations, which might be attributed to the deletion of CFHR3 and CFHR1 genes but not previously identified disease-associated exonic variants of CFH. This study provides the first evidence for consistent association between CFH/CFHRs and SLE across multi-ancestral SLE datasets, providing new insights into the role of complement regulators in the pathogenesis of SLE.

Atypical haemolytic uraemic syndrome (aHUS) is frequently associated with mutations in the gene encoding complement factor H (CFH). The clinical response to plasma therapy in aHUS is variable. We present here our experience of plasma therapy in three aHUS patients with CFH mutations. Three children presented aged 4, 22 and 6 months (patients 1–3 respectively) in acute kidney injury requiring dialysis. Plasma therapy consisting of plasma filtration (patient 1) or plasma exchange (PEX; patients 2 and 3) was commenced early following presentation. This resulted in aHUS remission and cessation of dialysis after 2 weeks, 9 days and 2 weeks respectively. Relapses were common and associated with increasing the interval between PEX, but all responded to intensification of PEX therapy. Patient 1 recovered 50% of renal function after first presentation. She had four relapses and started peritoneal dialysis 41 months after presentation. Mutation screening of CFH showed a missense mutation (c.3546 G > T, p.Arg1182Ser) in exon 23. PEX in patient 2 was slowly tapered over 4 months to fortnightly sessions, but she relapsed when PEX was extended to every 4 weeks. Renal function remained normal 12 months post-presentation. Mutation screening of CFH showed a mutation in exon 23 (c.3590 T > C, p.Val1197Ala) and two additional sequence variants in exons 3 and 4. Patient 3 had two relapses associated with intercurrent illnesses concurrent with reducing PEX to weekly doses. Renal function was normal 5 months post-presentation. All three patients showed a good response to PEX with improved renal function both initially and following a relapse. Further research is necessary to determine the best maintenance strategy to delay or prevent end-stage kidney disease.

Genomic disorders affecting the genes encoding factor H (fH) and the 5 factor H related proteins have been described in association with atypical hemolytic uremic syndrome. These include deletions of CFHR3, CFHR1, and CFHR4 in association with fH autoantibodies and the formation of a hybrid CFH/CFHR1 gene. These occur through nonallelic homologous recombination secondary to the presence of large segmental duplications (macrohomology) in this region. Using multiplex ligation-dependent probe amplification to screen for such genomic disorders, we have identified a large atypical hemolytic uremic syndrome family where a deletion has occurred through microhomology-mediated end joining rather than nonallelic homologous recombination. In the 3 affected persons of this family, we have shown that the deletion results in formation of a CFH/CFHR3 gene. We have shown that the protein product of this is a 24 SCR protein that is secreted with normal fluid-phase activity but marked loss of complement regulation at cell surfaces despite increased heparin binding. In this study, we have therefore shown that microhomology in this area of chromosome 1 predisposes to disease associated genomic disorders and that the complement regulatory function of fH at the cell surface is critically dependent on the structural integrity of the whole molecule.

Atypical haemolytic uraemic syndrome (aHUS) is a disease characterized by complement overactivation in which inherited defects in complement genes and acquired autoantibodies against complement regulatory proteins have been described. Identification of the underlying defect can both predict disease outcome and guide treatment. The ability to remove inhibitory autoantibodies and hyper-active complement components in addition to its ability to replace defective complement regulators means that plasma exchange is currently first-line therapy. In those with factor H and factor I mutations who do progress to end-stage renal failure, renal transplantation usually fails due to recurrent HUS. In this situation, combined liver-kidney transplantation has been suggested to correct the underlying genetic defect. Newer agents, such as the complement inhibitor eculizumab, may herald a new era in the treatment of aHUS.

Atypical hemolytic uremic syndrome was diagnosed in a 62-year-old man. Sequencing of the CFH gene, which encodes complement factor H, revealed a heterozygous adenine to guanine mutation at nucleotide 3550 of the complementary DNA, leading to a predicted substitution of alanine for threonine at amino acid position 1184 in the protein (c.3550A>G, p.Thr1184Ala). Three years later, he received a simultaneous liver-kidney transplant with plasmapheresis and intratransplant plasma infusion. The postoperative course was complicated by an anastomotic biliary stricture that was treated successfully using endoscopic stenting. One year later, he has excellent function of both transplants, emphasizing that simultaneous liver-kidney transplant is a valuable treatment option in the management of adult patients with atypical hemolytic uremic syndrome.

A 38-year-old lady (III.1 in Figure 1) was referred to the nephrology services with an increase in her plasma creatinine from 108 μmol/l [normal range (NR) 49–90 μmol/l] to 147 μmol/l over a 5-year period. She had previously been seen by a nephrologist at the age of 19 years when an abdominal ultrasound scan (USS) had shown a dysplastic left kidney as an incidental finding. At that time, an isotope renogram showed preserved function of the right kidney, while the left kidney contributed only 24% of total renal function. There was no history of urinary infection, she was normotensive and 24-h protein excretion was 11.1 mmol/l) at 2 h. She was also affected by congenital combined growth hormone (GH) and gonadotrophin hormone deficiencies, with a small pituitary on MR imaging. Abdominal USS at the age of 19 demonstrated an infantile uterus, and unidentifiable ovaries, consistent with her prepubertal status at the time. Figure 1. Pedigree, clinical characteristics and genotype of family. Age in years of diagnosis of diabetes, where known. Asterisk indicates HNF1A mutation P291fsinsC identified. Key: shading top left (diabetes), top right (renal dysplasia), bottom right (growth hormone deficiency), bottom left (hypothyroid). On clinical review, there was no evidence of diabetic retinopathy or neuropathy. Medications included …