Identification of single-gene causes of steroid-resistant nephrotic syndrome (SRNS) has furthered the understanding of the pathogenesis of this disease. Here, using a combination of homozygosity mapping and whole human exome resequencing, we identified mutations in the aarF domain containing kinase 4 (ADCK4) gene in 15 individuals with SRNS from 8 unrelated families. ADCK4 was highly similar to ADCK3, which has been shown to participate in coenzyme Q 10 (CoQ 10 ) biosynthesis. Mutations in ADCK4 resulted in reduced CoQ 10 levels and reduced mitochondrial respiratory enzyme activity in cells isolated from individuals with SRNS and transformed lymphoblasts. Knockdown of adck4 in zebrafish and Drosophila recapitulated nephrotic syndrome-associated phenotypes. Furthermore, ADCK4 was expressed in glomerular podocytes and partially localized to podocyte mitochondria and foot processes in rat kidneys and cultured human podocytes. In human podocytes, ADCK4 interacted with members of the CoQ 10 biosynthesis pathway, including COQ6, which has been linked with SRNS and COQ7. Knockdown of ADCK4 in podocytes resulted in decreased migration, which was reversed by CoQ 10 addition. Interestingly, a patient with SRNS with a homozygous ADCK4 frameshift mutation had partial remission following CoQ 10 treatment. These data indicate that individuals with SRNS with mutations in ADCK4 or other genes that participate in CoQ 10 biosynthesis may be treatable with CoQ 10 .

OBJECTIVETo assess the proportion of youth with type 1 diabetes under the care of pediatric endocrinologists in the United States meeting targets for HbA1c, blood pressure (BP), BMI, and lipids.RESEARCH DESIGN AND METHODSData were evaluated for 13,316 participants in the T1D Exchange clinic registry younger than 20 years old with type 1 diabetes for ≥1 year.RESULTSAmerican Diabetes Association HbA1c targets of <8.5% for those younger than 6 years, <8.0% for those 6 to younger than 13 years old, and <7.5% for those 13 to younger than 20 years old were met by 64, 43, and 21% of participants, respectively. The majority met targets for BP and lipids, and two-thirds met the BMI goal of <85th percentile.CONCLUSIONSMost children with type 1 diabetes have HbA1c values above target levels. Achieving American Diabetes Association goals remains a significant challenge for the majority of youth in the T1D Exchange registry.

Helmsley Charitable Trust.

Abbreviations: NPHS2: nephrosis 2, steroid-resistant ; SRNS: steroid-resistant nephrotic syndrome Introductory paragraphNephrotic syndrome is the consequence of damage to the glomerular filtration barrier, and it refers to the clinical symptoms of heavy proteinuria, hypoalbuminemia, edema and hyperlipidemia. The steroidresistant form of nephrotic syndrome (SRNS) has a poor prognosis, as it often leads to endstage renal disease (ESRD) 1,2 . Mutations in more than 20 genes have been identified in monogenic forms of SRNS, most of which encode podocyte proteins3-5. NPHS2, encoding podocin, is the most frequently mutated of these genes and is responsible for 12-18% of SRNS cases 3,6,7 . Podocin accumulates in dimeric or oligomeric forms in lipid raft microdomains at the podocyte slit diaphragm, which is the key component of the glomerular filtration barrier. On the basis of its predicted structure, podocin belongs to the stomatin protein family, with a hairpin-like intramembrane loop and intracellular N and C termini. The C-terminal portions of both stomatin and podocin are responsible for dimerization 6,[8][9][10][11][12] .Individuals with NPHS2 mutations typically develop SRNS before 6 years of age and progress to ESRD during their first decade of life6. The phenotype can be less severe in the setting of a trans association of an NPHS2 mutation and the polymorphism c.686G>A (p.Arg229Gln, rs61747728), a genotype we hereafter denote as p.[Arg229Gln];[mut] that causes SRNS with a median age at diagnosis of 13 years (range, 0-39 years) and progression to ESRD by 26 years (range, 10-50 years) 7,[13][14][15][16][17][18] . Nevertheless, the p.Arg229Gln variant in the homozygous state does not cause SRNS 19,20 .On the basis of the 15× higher allele frequency of p.Arg229Gln (357/13,006, 2.7%) than the cumulative allele frequency of the known disease-causing variants 13-18,21-43 (24/13,006, 0.18%)

Background Fear of hypoglycemia is common in parents of young children with type 1 diabetes (T1D), but little is known about the specific fears that parents most often experience. Hypoglycemia fear has been associated with poorer glycemic control in older children, though not yet studied in a large cohort of very young children. Materials and Methods Parents of 549 children <7 years (mean 5.2 ± 1.2 years [19% <3 years]) with a mean diabetes duration of 2.4 ± 1.0 years (range 1‐6 years) and mean HbA1c 8.2% ± 1.1% (66 ± 12 mmol/mol) registered in the T1D Exchange completed the worry scale of the Hypoglycemia Fear Survey modified for parents (HFS‐P). Results Mean parental fear of hypoglycemia worry score was 36.1 ± 23.1 (possible range 0‐100), with most frequent worries related to the child having a low while asleep and the child not recognizing a low. The mean worry score was not associated with the child's age, glycemic control, or recent severe hypoglycemic event. Parental worries about lows while sleeping were significantly higher in pump users than non‐users (61% vs. 45%; P < .001), and tended to be higher in CGM users than non‐users (62% vs 51%; P = .02). Conclusions The greatest worries of parents of young children with T1D were related to hypoglycemia during sleep and other times/circumstances during which it would be difficult to detect hypoglycemia. Using advanced diabetes technologies may be an effort to temper fears about hypoglycemia during sleep, though the directionality of this relationship is undetermined. Additional studies can clarify this association and leverage use of diabetes technologies to improve glycemic control.

Context Use of continuous glucose monitoring (CGM) is increasing for insulin-requiring patients with diabetes. Although data on glycemic profiles of healthy, nondiabetic individuals exist for older sensors, assessment of glycemic metrics with new-generation CGM devices is lacking. Objective To establish reference sensor glucose ranges in healthy, nondiabetic individuals across different age groups using a current generation CGM sensor. Design Multicenter, prospective study. Setting Twelve centers within the T1D Exchange Clinic Network. Patients or Participants Nonpregnant, healthy, nondiabetic children and adults (age ≥6 years) with nonobese body mass index. Intervention Each participant wore a blinded Dexcom G6 CGM, with once-daily calibration, for up to 10 days. Main Outcome Measures CGM metrics of mean glucose, hyperglycemia, hypoglycemia, and glycemic variability. Results A total of 153 participants (age 7 to 80 years) were included in the analyses. Mean average glucose was 98 to 99 mg/dL (5.4 to 5.5 mmol/L) for all age groups except those over 60 years, in whom mean average glucose was 104 mg/dL (5.8 mmol/L). The median time between 70 to 140 mg/dL (3.9 to 7.8 mmol/L) was 96% (interquartile range, 93 to 98). Mean within-individual coefficient of variation was 17 ± 3%. Median time spent with glucose levels &gt;140 mg/dL was 2.1% (30 min/d), and median time spent with glucose levels &lt;70 mg/dL (3.9 mmol/L) was 1.1% (15 min/d). Conclusion By assessing across age groups in a healthy, nondiabetic population, normative sensor glucose data have been derived and will be useful as a benchmark for future research studies.

LMX1B encodes a homeodomain-containing transcription factor that is essential during development. Mutations in LMX1B cause nail-patella syndrome, characterized by dysplasia of the patellae, nails, and elbows and FSGS with specific ultrastructural lesions of the glomerular basement membrane (GBM). By linkage analysis and exome sequencing, we unexpectedly identified an LMX1B mutation segregating with disease in a pedigree of five patients with autosomal dominant FSGS but without either extrarenal features or ultrastructural abnormalities of the GBM suggestive of nail-patella-like renal disease. Subsequently, we screened 73 additional unrelated families with FSGS and found mutations involving the same amino acid (R246) in 2 families. An LMX1B in silico homology model suggested that the mutated residue plays an important role in strengthening the interaction between the LMX1B homeodomain and DNA; both identified mutations would be expected to diminish such interactions. In summary, these results suggest that isolated FSGS could result from mutations in genes that are also involved in syndromic forms of FSGS. This highlights the need to include these genes in all diagnostic approaches to FSGS that involve next-generation sequencing.

Several genes, mainly involved in podocyte cytoskeleton regulation, have been implicated in familial forms of primary FSGS. We identified a homozygous missense mutation (p.P209L) in the TTC21B gene in seven families with FSGS. Mutations in this ciliary gene were previously reported to cause nephronophthisis, a chronic tubulointerstitial nephropathy. Notably, tubular basement membrane thickening reminiscent of that observed in nephronophthisis was present in patients with FSGS and the p.P209L mutation. We demonstrated that the TTC21B gene product IFT139, an intraflagellar transport-A component, mainly localizes at the base of the primary cilium in developing podocytes from human fetal tissue and in undifferentiated cultured podocytes. In contrast, in nonciliated adult podocytes and differentiated cultured cells, IFT139 relocalized along the extended microtubule network. We further showed that knockdown of IFT139 in podocytes leads to primary cilia defects, abnormal cell migration, and cytoskeleton alterations, which can be partially rescued by p.P209L overexpression, indicating its hypomorphic effect. Our results demonstrate the involvement of a ciliary gene in a glomerular disorder and point to a critical function of IFT139 in podocytes. Altogether, these data suggest that this homozygous TTC21B p.P209L mutation leads to a novel hereditary kidney disorder with both glomerular and tubulointerstitial damages.