Ewa Elenberg

Feeding problems in cystinosis

Abstract. Nephropathic cystinosis, a rare autosomal recessive storage disease characterized by intracellular storage of free cystine due to a defect in lysosomal cystine transport, is the most common cause of Fanconi syndrome in childhood. Although manifestations of extrarenal organ involvement during the course of the disease are diverse, the spectrum of gastrointestinal (GI) problems has not yet been examined. In responses to a questionnaire from 70 (35%) of the 200 registered members of the Cystinosis Foundation, we found that GI symptoms are more common, more diverse, and occur at a younger age in patients with cystinosis than previously recognized. Ninety-three percent of interviewed subjects had GI symptoms at initial presentation, and the overall lifetime prevalence of GI problems in this group was 100%. Thirty percent have received gastric/jejunal tube feedings, and 7% required continuous or intermittent total parenteral nutrition. Fifty percent have been formally tested for GI abnormalities, and among these 77% have documented functional abnormalities (reflux/dysmotility, pseudo-obstruction, swallowing dysfunction). Early recognition and aggressive therapy of GI problems in cystinotic patients may ameliorate or prevent the development of disabling symptoms.

Quality of Life is Improved and Kidney Function Preserved in Patients with Nephropathic Cystinosis Treated for 2 Years with Delayed-Release Cysteamine Bitartrate *

Objectives To determine the long-term effects of delayed-release cysteamine bitartrate (DR-CYS) based on our previous work that established the short-term noninferiority of DR-CYS every 12 hours compared with immediate-release cysteamine bitartrate every 6 hours. Study design We conducted a prospective, controlled, open label, single-arm study of DR-CYS for 2 years in 40 patients to assess efficacy in depletion of cystine in peripheral white blood cells, to assess the dose required to maintain white blood cell content of cystine <1 nmol ½ cystine/mg protein, to measure quality of life using the Pediatric Quality of Life Inventory, change in estimated glomerular filtration rate, and change in height Z-score. Results Through 24 months of study, the mean white blood cell content of cystine was always <1 nmol ½ cystine/mg protein, and the dose of DR-CYS decreased from 43.5-40.1 mg/kg/d (P = .05), and the significant improvement in social function, school function, and in total function scores on the Pediatric Quality of Life Inventory remained. The estimated glomerular filtration rate was maintained and growth velocity was maintained at 24 months compared with the baseline height Z-score. Conclusions The use of a DR-CYS administered every 12 hours to patients with cystinosis is of great benefit to their quality of life and to important biomarkers of disease control, when studied in a prospective, controlled fashion. We suggest that DR-CYS should be considered for substrate depletion in patients with cystinosis.

Whole-exome sequencing in the molecular diagnosis of individuals with congenital anomalies of the kidney and urinary tract and identification of a new causative gene

Purpose:To investigate the utility of whole-exome sequencing (WES) to define a molecular diagnosis for patients clinically diagnosed with congenital anomalies of kidney and urinary tract (CAKUT).Methods:WES was performed in 62 families with CAKUT. WES data were analyzed for single-nucleotide variants (SNVs) in 35 known CAKUT genes, putatively deleterious sequence changes in new candidate genes, and potentially disease-associated copy-number variants (CNVs).Results:In approximately 5% of families, pathogenic SNVs were identified in PAX2, HNF1B, and EYA1. Observed phenotypes in these families expand the current understanding about the role of these genes in CAKUT. Four pathogenic CNVs were also identified using two CNV detection tools. In addition, we found one deleterious de novo SNV in FOXP1 among the 62 families with CAKUT. The clinical database of the Baylor Miraca Genetics laboratory was queried and seven additional unrelated individuals with novel de novo SNVs in FOXP1 were identified. Six of these eight individuals with FOXP1 SNVs have syndromic urinary tract defects, implicating this gene in urinary tract development.Conclusion:We conclude that WES can be used to identify molecular etiology (SNVs, CNVs) in a subset of individuals with CAKUT. WES can also help identify novel CAKUT genes.Genet Med 19 4, 412–420.

Potocki-Shaffer syndrome: comprehensive clinical assessment, review of the literature, and proposals for medical management.

Potocki–Shaffer syndrome is a rare contiguous gene deletion syndrome due to haploinsufficiency of the 11p11.2p12 region and is characterized by craniofacial abnormalities, developmental delay, intellectual disability, multiple exostoses, and biparietal foramina. In this study, six patients with the Potocki–Shaffer syndrome were identified and evaluated using a multidisciplinary protocol that included assessments by a geneticist, ophthalmologist, otolaryngologist, orthopedist, nephrologist, audiologist, and neuropsychologist. Diagnostic studies included skeletal survey, magnetic resonance imaging of the brain, renal ultrasound, complete blood count, comprehensive metabolic panel, thyroid studies, and urinalysis. Using array comparative genomic hybridization, we further characterized the deletion in five of these patients. The results of these evaluations were combined with a comprehensive review of reported cases. Our data highlight the characteristic facial features, biparietal foramina, moderate‐to‐severe developmental delay and intellectual disability, myopia and strabismus, and multiple exostoses seen with this disorder. We also identify for the first time an association of Potocki–Shaffer syndrome with sensorineural hearing loss and autistic behaviors. Finally, we provide recommendations for the health maintenance of patients with Potocki–Shaffer syndrome.

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.

IgA nephropathy presenting with renal failure and pulmonary hemorrhage

Pulmonary renal syndromes are unusual, but frequently life-threatening manifestations of a distinct group of disorders in the pediatric age group. Although IgA nephropathy is a common cause of hematuria, it is an extremely rare cause of pulmonary renal syndrome, causing high mortality, and has mostly been reported in adult patients. We describe the youngest patient with this presentation reported to date, a 14-year-old male, who presented with end stage renal disease and pulmonary hemorrhage and was found to have IgA nephropathy by renal biopsy and pulmonary capillaritis by open lung biopsy. His lung disease was successfully treated with immunosuppressive medications. Despite this being a rare manifestation of IgA nephropathy, clinicians need to be aware of this presentation as it is potentially fatal, but amenable to aggressive immunosuppression.

A unique case of intraventricular hemorrhage associated with posterior reversible encephalopathy syndrome in an adolescent.

Intraventricular hemorrhage is a rare finding in patients with the posterior reversible encephalopathy syndrome and generally carries a poor prognosis. We report a unique case of an 18-year-old girl with glomerulonephritis who developed posterior reversible encephalopathy syndrome without hypertension but with a primary intraventricular hemorrhage and subarachnoid blood without demonstrable parenchymal blood. The normotensive presentation of posterior reversible encephalopathy syndrome and intraventricular hemorrhage in association with systemic vasculitis is rare. Our patient had a good initial outcome and was discharged with resolution of her symptoms and signs of raised intracranial pressure.

Deficiency of complement factor H-related proteins and autoantibody-positive hemolytic uremic syndrome in an infant with combined partial deficiencies and autoantibodies to complement factor H and ADAMTS13

ABSTRACT A 3-month-old male infant developed an extremely severe episode of atypical hemolytic uremic syndrome (aHUS) associated with partial deficiencies of full-length complement factor H (FH; ∼15% of infant normal) and a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) (39% of normal) and autoantibodies reactive with both proteins. His FH and ADAMTS13 genes were normal, indicating that the partial deficiencies were acquired, probably as the result of autoantibodies against full-length FH and ADAMTS13. The child also had a homozygous deletion of the complement factor H–related (CFHR)3–CFHR1 portion in the complement factor H (CFH) gene cluster. He therefore had deficiency of CFHR proteins and autoantibody-positive hemolytic uremic syndrome (DEAP-HUS) with an unusual early onset associated with a partial deficiency of ADAMTS13 and an anti-ADAMTS13 autoantibody. His clinical episode of aHUS responded to plasma infusion and subsequent treatment with mycophenolate and rituximab. We believe that this is the first report of DEAP-HUS in an infant with partial deficiencies in both ADAMTS13 and full-length FH acquired in association with autoantibodies to both proteins.

Intra‐procedural continuous dialysis to facilitate interventional catheterization in pediatric patients with severe renal failure

Interventional catheterization procedures may be needed for patients with severe renal failure who are dependent on dialysis. To avoid the risk of fluid overload and electrolyte derangement during complex procedures in this oliguric/anuric patient population, we performed intra‐procedural dialysis, either continuous renal replacement therapy (CRRT) or continous cycling peritoneal dialysis (CCPD).