Julian P. Midgley

The 2014 International Workshop on Alport Syndrome.

Alport syndrome, historically referred to as hereditary glomerulonephritis with sensorineural deafness and anterior lenticonus, is a genetic disease of collagen α3α4α5(IV) resulting in renal failure. The collagen α3α4α5(IV) heterotrimer forms a network that is a major component of the kidney glomerular basement membrane (GBM) and basement membranes in the cochlea and eye. Alport syndrome, estimated to affect 1 in 5000–10,000 individuals, is caused by mutations in any one of the three genes that encode the α chain components of the collagen α3α4α5(IV) heterotrimer: COL4A3, COL4A4, and COL4A5. Although angiotensin-converting enzyme inhibition is effective in Alport syndrome patients for slowing progression to end-stage renal disease, it is neither a cure nor an adequate long-term protector. The 2014 International Workshop on Alport Syndrome, held in Oxford, UK, from January 3–5, was organized by individuals and families living with Alport syndrome, in concert with international experts in the clinical, genetic, and basic science aspects of the disease. Stakeholders from diverse communities—patient families, physicians, geneticists, researchers, Pharma, and funding organizations—were brought together so that they could meet and learn from each other and establish strategies and collaborations for the future, with the overall aim of discovering much needed new treatments to prolong kidney function.

Outcomes of kidney transplantation in children with nephronophthisis: An analysis of the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) Registry

Abstract:  NPHP is an autosomal recessive chronic tubulointerstitial nephropathy that progresses to ESRD. In the 2006 NAPRTCS report, NPHP was the primary diagnosis in 2.8% of all renal transplant patients. At our pediatric center, that covers a population in which the NPHP1 gene is prevalent, 24% of transplant recipients had a primary diagnosis of NPHP. Since no previous literature reports have documented kidney transplant outcomes in patients with NPHP, a review of the 2006 NAPRTCS database was performed. The results of this review illustrate that patients with NPHP as their underlying kidney disease have a significantly better overall graft survival when compared with all other patients registered in the NAPRTCS database. Sub‐analysis demonstrated that this benefit is statistically significant only for LD kidney transplant recipients. CrCl was better in NPHP at all time points from transplant up to five‐yr follow‐up. Moreover, in NPHP LD transplant recipients the decline of CrCl over five yr was slower compared with non‐NPHP LD transplant recipients. Rates of thrombosis, acute, and chronic rejection as well as causes of graft failure were similar in NPHP patients and all other patients. This review demonstrates that NPHP transplant recipients have excellent outcomes that are shown to be better compared with the general pediatric transplant population.

Meckel syndrome in the Hutterite population is actually a Joubert-related cerebello-oculo-renal syndrome.

Meckel syndrome (MKS) is a rare lethal autosomal recessive disorder characterized by the presence of occipital encephalocele, cystic kidneys, fibrotic changes of the liver and polydactyly. Joubert syndrome (JS)‐related disorders (JSRDs) or cerebello‐oculo‐renal syndromes (CORS) are a group of recessively inherited conditions characterized by a molar tooth sign (MTS) on cranial MRI, a set of core clinical features (developmental delay/mental retardation, hypotonia, ataxia, episodic breathing abnormalities, abnormal eye movements) and variable involvement of other systems including renal, ocular, central nervous system, craniofacial, hepatic, and skeletal. A significant clinical overlap between MKS and JSRD/CORS has been recognized in the literature. We describe a group of 10 Hutterite patients, of which 7 had been previously diagnosed with MKS, with a JSRD. Clinical features include variable early mortality, cognitive handicap, a characteristic dysmorphic facial appearance, hypotonia, ataxia, abnormal breathing pattern, nystagmus, and MTS on MRI. Additional features include occipital encephalocele, posterior fossa fluid collections resembling Dandy–Walker malformation, hydrocephalus, coloboma, and renal disease. This JSRD is a recognizable dysmorphic syndrome characterized by hypertelorism, deep‐set eyes, down‐slanting palpebral fissures, ptosis, arched eyebrows with medial sparseness, square nasal tip, short philtrum with tented upper lip, open mouth with down‐turned corners, and posteriorly rotated low‐set ears. Renal disease is present in 70% of patients and is characterized by cystic kidneys, abnormalities in renal function and hypertension. Homozygous deletions of NPHP1 and the known loci for JS/JSRD and MKS were excluded by identity‐by‐descent mapping studies suggesting that this condition in the Hutterites represents yet another locus for a JSRD.

Controversies and research agenda in nephropathic cystinosis: conclusions from a “Kidney Disease: Improving Global Outcomes” (KDIGO) Controversies Conference

Nephropathic cystinosis is an autosomal recessive metabolic, lifelong disease characterized by lysosomal cystine accumulation throughout the body that commonly presents in infancy with a renal Fanconi syndrome and, if untreated, leads to end-stage kidney disease (ESKD) in the later childhood years. The molecular basis is due to mutations in CTNS, the gene encoding for the lysosomal cystine-proton cotransporter, cystinosin. During adolescence and adulthood, extrarenal manifestations of cystinosis develop and require multidisciplinary care. Despite substantial improvement in prognosis due to cystine-depleting therapy with cysteamine, no cure of the disease is currently available. Kidney Disease: Improving Global Outcomes (KDIGO) convened a Controversies Conference on cystinosis to review the state-of-the-art knowledge and to address areas of controversies in pathophysiology, diagnostics, monitoring, and treatment in different age groups. More importantly, promising areas of investigation that may lead to optimal outcomes for patients afflicted with this lifelong, systemic disease were discussed with a research agenda proposed for the future.

Angiotensinogen M235T genotype predicts progression in chronic renal allograft dysfunction

Background. Genotypes of the renin-angiotensin system have been implicated in essential hypertension and in progression of native kidney diseases, but gene effects on progression in chronic renal allograft dysfunction are unclear. Methods. To examine gene effects on long-term renal allograft function, we conducted a prospective cohort study of 210 nondiabetic renal allograft recipients younger than 36 years of age who underwent transplantation between 1980 and 1993 and were followed up through 1999. All grafts survived more than 1 year and all subjects received cyclosporine-based immunosuppression. DNA was analyzed by polymerase chain reaction for the angiotensin-converting enzyme insertion/deletion and angiotensinogen (AGT) M235T polymorphisms. Linear regression multivariate modeling of the slope of the inverse creatinine-versus-time, survival analyses for time-to-sustained doubling of baseline serum creatinine, time-to-graft loss, and a composite endpoint including patient death were performed. Results. Mean follow-up time was 8.4±3 years. Genotype frequencies for each marker system did not deviate significantly from the Hardy-Weinberg equilibrium. The slope of the inverse creatinine-versus-time for AGT 235T/T and M/T was significantly increased compared with M/M (P <0.0001). The AGT 235T/T genotype was also associated with a shorter time-to-sustained doubling of serum creatinine (P =0.001). When subjects were divided into quartiles based on slope magnitude, the frequency of the AGT 235T/T genotype was overrepresented in the fastest progressing group compared with the slowest (P =0.001). The AGT 235T/T genotype was also associated with shorter time-to-graft loss (P =0.007) and the composite endpoint (P =0.001). Conclusion. The AGT 235 T allele independently influences long-term decline in renal allograft function.

Natural history of adolescent-onset cystinosis

Cystinosis is a rare autosomal recessive disease caused by mutations of the CTNS gene in which cystine accumulates throughout the body as a result of a defective efflux of cystine from lysosomes. Three phenotypic forms have been described according to the age of onset and the severity of the clinical symptoms: infantile, intermediate, and ocular non-nephropathic cystinosis. Here we report the natural history of cystinosis in a 55-year-old man with intermediate nephropathic cystinosis diagnosed at 9 years of age. Although tubulopathy was unnoticed in the early years, he required transplantation at age 16. Sequencing analysis of all the CTNS exons revealed that the proband is homozygous for a 21-bp in-frame deletion in exon 5 (c. 198_218del21), resulting in an in-frame deletion of 7 amino acids from the N-terminal domain of the cystinosin protein. Our patient has had relatively mild extra-renal disease despite lack of early cysteamine therapy. He has been able to attend university and pursue a professional career into the 6th decade.

Seizures in children after kidney transplantation: has the risk changed and can we predict who is at greatest risk?

Abstract:  Children undergoing kidney transplantation are at increased risk for symptomatic seizures with a previously reported incidence of approximately 20%. Little data exist to help predict which children may be at risk. We retrospectively reviewed all children who underwent kidney transplantation evaluation at our center between October 1993 and August 2007 and identified 41 children who had an EEG prior to transplant. Demographic data as well as the following were collected: immunosuppressive medications, developmental status, history of seizures, family history of seizures, post‐transplant seizures and EEG results. EEGs were classified as normal or abnormal. Prior to transplantation, one child had a history of febrile seizures and six experienced afebrile seizures. Nine (22%) children identified had an abnormal EEG prior to transplant. In eight cases the EEG was non‐epileptiform and in one case was epileptiform. Abnormal EEGs did not correlate with a family history of seizures. Delayed development was noted in seven children and was not associated with an epileptiform EEG. Following kidney transplantation, no child experienced a seizure. Our single center study suggests that current rates of seizures following kidney transplantation are lower than previously reported and that routine EEG as part of the pretransplant evaluation in these children is of limited use to predict those at risk.

ALG9-CDG: New clinical case and review of the literature.

Congenital disorders of glycosylation (CDG) are a group of metabolic diseases resulting from defects in glycan synthesis or processing. The number of subgroups and their phenotypic spectrums continue to expand with most related to deficiencies of N-glycosylation. ALG9-CDG (previously CDG-IL) is the result of a mutation in ALG9. This gene encodes the enzyme alpha-1,2-mannosyltransferase. To date, a total of 10 patients from 6 different families have been reported with one of four ALG9 mutations. Seven of these patients had a similar phenotype with failure to thrive, dysmorphic features, seizures, hepatic and/or renal cysts; the other three patients died in utero from a lethal skeletal dysplasia. This report describes an additional patient with ALG9-CDG who has a milder phenotype. This patient is a term female born to Caucasian, Canadian, non-consanguineous parents of Scottish decent. Prenatally, dysmorphic features, numerous renal cysts and minor cardiac malformations were detected. Post-natally, dysmorphic features included shallow orbits, micrognathia, hypoplastic nipples, talipes equinovarus, lipodystrophy and cutis marmorata. She developed failure to thrive and seizures. The metabolic work-up included analysis of a transferrin isoelectric focusing, which showed a type 1 pattern. This was confirmed by glycan profiling, which identified ahomozygous mutation in ALG9, c.860A > G (p.Tyr287Cys) (NM_1234567890). This had been previously published as a pathogenic mutation in two Canadian patients. Our goal is to contribute to the growing body of knowledge for this disorder by describing the phenotypic spectrum and providing further insight on prognosis.