Biallelic loss-of-function variants in KCNJ16 presenting with hypokalemic metabolic acidosis.

KCNJ16 encodes Kir5.1 and acts in combination with Kir4.1, encoded by KCNJ10, to form an inwardly rectifying K+ channel expressed at the basolateral membrane of epithelial cells in the distal nephron. This Kir4.1/Kir5.1 channel is critical for controlling basolateral membrane potential and K+ recycling, the latter coupled to Na-K-ATPase activity, which determines renal Na+ handling. Previous work has shown that Kcnj16-/- mice and SSKcnj16-/- rats demonstrate hypokalemic, hyperchloremic metabolic acidosis. Here, we present the first report of a patient identified to have biallelic loss-of-function variants in KCNJ16 by whole exome sequencing who presented with chronic metabolic acidosis with exacerbations triggered by minor infections.

Can transition to adult care for transplant recipients be improved by intensified services while patients are still in pediatrics?

Context-Transferring out of pediatrics is a vulnerable time for transplant recipients. Use of a transition coordinator before and after transfer improves outcomes, although it is unclear whether placing a transition coordinator in pediatrics alone is beneficial. Objective-To determine if incorporating a transition coordinator in pediatrics only is associated with stable outcomes for kidney transplant recipients. Design-A retrospective chart review was conducted on outcomes for kidney transplant recipients who shifted service location between 2008 and 2012. Setting-A pediatric and adult transplant unit. Patients-Twenty-two patients transferred during the study period. Intervention-Twelve patients received more intensified preparation from the team's social worker, whose role was aligned with a transition coordinator position; 10 patients received standard care. Main Outcome Measures-The primary outcome was medication adherence, using a validated measure, standard deviations of tacrolimus blood levels. A standard deviation greater than 2.5 has been established as a threshold associated with poor outcomes such as rejection. Standard deviation of tacrolimus levels was compared for 1 year before and 1 year after transfer. Results-Medication adherence worsened from 1 year before (2.03 [SD, 0.75]) to 1 year after transfer (2.95 [SD, 1.38]; t = -;3.07, P = .007). A repeated-measures analysis of variance indicated that this pattern was the same for patients who did and patients who did not receive intensified services in pediatrics (F1,16 = 1.07, P = .32).

Epstein-Barr virus-associated smooth muscle tumors in children following solid organ transplantation: a review.

EBV-SMT are a rare entity following organ transplantation. Given the rarity of the tumor, there is no standard approach to diagnosis and treatment. A literature search identified 28 reported cases of EBV-SMT in addition to our own experience with one case. The aim of this review is to summarize the existing data regarding pathogenesis, diagnosis, and treatment.

Growth in children with chronic kidney disease: a report from the Chronic Kidney Disease in Children Study.

BACKGROUND: Growth failure is common among children with chronic kidney disease (CKD). We examined the relationship of growth parameters with glomerular filtration rate (GFR), CKD diagnosis, sex and laboratory results in children with CKD. METHODS: Baseline data from 799 children (median age 11.0 years, median GFR 49.9 mL/min/1.73 m(2)) participating in the Chronic Kidney Disease in Children Study were examined. Growth was quantified by age-sex-specific height, weight, body mass index (BMI-age), and height-age-sex-specific BMI (BMI-height-age) standard deviation scores (SDS). RESULTS: Median height and weight SDS were -0.55 [interquartile range (IQR) -1.35 to 0.19] and 0.03 (IQR -0.82 to 0.97), respectively. Girls with non-glomerular CKD were the shortest (median height SDS -0.83; IQR -1.62 to -0.02). Compared to those with a serum bicarbonate (CO2) level of ≥ 22 mEq/L, children with CO2 of <18 mEq/L had a height SDS that was on average 0.67 lower [95 % confidence interval (CI) -0.31 to -1.03]. Only 23 % of children with a height SDS of ≤-1.88 were prescribed growth hormone therapy. Forty-six percent of children with glomerular CKD were overweight or obese (BMI-height-age ≥ 85th percentile). CONCLUSIONS: Growth outcomes in a contemporary cohort of children with CKD remain suboptimal. Interventions targeting metabolic acidosis and overcoming barriers to recombinant human growth hormone usage may improve growth in this population.

Treatment of recurrent focal segmental glomerulosclerosis in pediatric kidney transplant recipients: effect of rituximab.

Recurrence of focal segmental glomerulosclerosis (FSGS) after renal transplantation is a complication that often leads to graft loss. There is no consensus on the optimal treatment of recurrent FSGS. Rituximab, a monoclonal antibody to CD20, may be a useful treatment of this complication. Methods. We report four pediatric cases of recurrent FSGS treated with rituximab and plasmapheresis. Results. Four children (2M/2F), age 15.3 ± 2.6, with recurrent FSGS posttransplant were identified. Four doses of rituximab were administered 171 ± 180 days posttransplant and 114 ± 169 days after the start of plasmapheresis. Three children responded with complete remission, one of whom relapsed after four months. One child had a partial response with a decrease in proteinuria that was not sustained. No adverse side effects were reported during treatment or followup (mean 22.5 months). Conclusions. Rituximab is a safe and well-tolerated ancillary treatment for recurrent FSGS in pediatric patients in conjunction with plasmapheresis.

The association between abnormal birth history and growth in children with CKD.

BACKGROUND AND OBJECTIVES: Poor linear growth is a well described complication of chronic kidney disease (CKD). This study evaluated whether abnormal birth history defined by low birth weight (LBW; <2500 g), prematurity (gestational age <36 weeks), small for gestational age (SGA; birth weight <10th percentile for gestational age), or intensive care unit (ICU) at birth were risk factors for poor growth outcomes in children with CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Growth outcomes were quantified by age-sex-specific height and weight z-scores during 1393 visits from 426 participants of the Chronic Kidney Disease in Children Study, an observational cohort of children with CKD. Median baseline GFR was 42.9 ml/min per 1.73 m(2), 21% had a glomerular diagnosis, and 52% had CKD for ≥ 90% of their lifetime. RESULTS: A high prevalence of LBW (17%), SGA (14%), prematurity (12%), and ICU after delivery (40%) was observed. Multivariate analyses demonstrated a negative effect of LBW (-0.43 ± 0.14; P < 0.01 for height and -0.37 ± 0.16; P = 0.02 for weight) and of SGA (-0.29 ± 0.16; P = 0.07 for height and -0.41 ± 0.19; P = 0.03 for weight) on current height and weight. In children with glomerular versus nonglomerular diagnoses, the effect of SGA (-1.08 versus -0.18; P = 0.029) on attained weight was more pronounced in children with a glomerular diagnosis. CONCLUSIONS: LBW and SGA are novel risk factors for short stature and lower weight percentiles in children with mild to moderate CKD independent of kidney function.

Lactate dehydrogenase as a predictor of kidney involvement in patients with sickle cell anemia.

A retrospective chart review of 40 patients with sickle cell anemia (SCA) between the ages of 5-19 years who were seen within a 1-year period was performed to determine clinical and laboratory correlates for microalbuminuria and proteinuria. Age, sex, height, body mass index (BMI), serum creatinine [and estimated glomerular filtration rate (eGFR) by Schwartz and MDRD formulas], type of SCA, hemoglobin (Hb) level [total Hb and hemoglobin F percentage (HbF%)], lactate dehydrogenase (LDH) level, reticulocyte count, blood pressure, history of splenectomy, history of hydroxyurea use, and history of transfusions were correlated with microalbuminuria and proteinuria by univariate and multivariate regression analysis. The prevalence of microalbuminuria and proteinuria among these patients was 15 and 5%, respectively. Univariate analyses revealed a significant correlation between LDH level and microalbuminuria (Pearson r=0.47, p=0.04) and between LDH level and proteinuria (Pearson r=0.48, p=0.035). Multivariate analysis revealed a significant correlation between microalbuminuria and LDH level (p = 0.04) when controlled for age, sex, eGFR, Hb level, HbF%, type of SCA, BMI, history of transfusions, and reticulocyte count. In this pediatric SCA population, LDH was found to correlate with the presence of microalbuminuria and proteinuria. Further studies are needed to confirm LDH as an early marker for the risk of kidney involvement among SCA patients.

Differential expression of profibrotic and growth factors in chronic allograft nephropathy.

BACKGROUND: Chronic allograft nephropathy (CAN) is a multifactorial process, where both immunological and nonimmunological factors play roles. Microarrays detect thousands of genes simultaneously. METHODS: We have analyzed gene expression profiles of 16 kidney transplant biopsy samples with CAN by high-density oligonucleotide microarrays, comparing to six normal transplant biopsies. Eight CAN biopsies showed nodular arteriolar hyalinization and one was positive for C4d staining. RESULTS: Hierarchical clustering analysis of the 22 biopsies revealed differential gene expression patterns in CAN versus the control biopsies. However, microarray analysis did not reveal differential gene expression patterns in patients with or without arteriolar hyalinization. Fifty percent of the 100 genes with highest hybridization intensities in a C4d positive sample were related to cellular and humoral immune response. Although 212 genes were upregulated a minimum of 1.5-fold, 112 genes were downregulated in CAN samples. There was differential expression of profibrotic and growth factors that while transforming growth factor-beta induced factor, thrombospondin 1, and platelet derived growth factor-C were up-regulated, vascular endothelial growth factor, epidermal growth factor, and fibroblast growth factors 1 and 9 were downregulated. Selected differentially expressed genes were confirmed in microdissected samples by real-time quantitative PCR. Immunopathologic examination of biopsies revealed strong TGF-beta but decreased glomerular VEGF expression in CAN. CONCLUSION: Microarrays might be an important tool to uncover the mechanisms of multifactorial diseases, such as CAN.