COL4A gene variants are common in children with hematuria and a family history of kidney disease

BACKGROUND

Inherited kidney diseases are a common cause of chronic kidney disease (CKD) in children. Identification of a monogenic cause of CKD is more common in children than in adults. This study evaluated the diagnostic yield and phenotypic spectrum of children who received genetic testing through the KIDNEYCODE sponsored genetic testing program.

METHODS

Unrelated children < 18 years of age who received panel testing through the KIDNEYCODE sponsored genetic testing program from September 2019 through August 2021 were included (N = 832). Eligible children met at least one of the following clinician-reported criteria: estimated GFR ≤ 90 ml/min/1.73 m2, hematuria, a family history of kidney disease, or suspected or biopsy confirmed Alport syndrome or focal segmental glomerulosclerosis (FSGS) in the tested individual or family member.

RESULTS

A positive genetic diagnosis was observed in 234 children (28.1%, 95% CI [25.2-31.4%]) in genes associated with Alport syndrome (N = 213), FSGS (N = 9), or other disorders (N = 12). Among children with a family history of kidney disease, 30.8% had a positive genetic diagnosis. Among those with hematuria and a family history of CKD, the genetic diagnostic rate increased to 40.4%.

CONCLUSIONS

Children with hematuria and a family history of CKD have a high likelihood of being diagnosed with a monogenic cause of kidney disease, identified through KIDNEYCODE panel testing, particularly COL4A variants. Early genetic diagnosis can be valuable in targeting appropriate therapy and identification of other at-risk family members. A higher resolution version of the Graphical abstract is available as Supplementary information.

CMV-associated collapsing focal segmental glomerulosclerosis after kidney transplant in a pediatric patient

BACKGROUND

Cytomegalovirus (CMV) is a significant cause of morbidity among immunocompromised patients who have undergone kidney transplantation and is known to rarely induce collapsing focal segmental glomerulosclerosis (FSGS) among adults.

METHODS

We present the first reported case of CMV-induced collapsing FSGS in a pediatric patient after kidney transplant.

RESULTS

Our patient underwent a deceased donor kidney transplant due to end-stage renal disease secondary to lupus nephritis. Approximately 4 months after transplantation, he developed signs of worsening kidney function in the setting of CMV viremia and was found to have collapsing features of FSGS on kidney transplant biopsy. He was managed with a prompt escalation of antiviral therapy along with a reduction of immunosuppression and recovered without significant complication. At follow-up, he continued to have undetectable CMV titers, creatinine within normal limits, and no significant proteinuria.

CONCLUSION

This report demonstrates CMV as a cause of collapsing FSGS and should be considered among pediatric transplant recipients who present with acute kidney injury, as should early assessment of APOL1 genetic status in both donor and recipient.

The KIDNEYCODE Program: Diagnostic Yield and Clinical Features of Individuals with CKD

Background

Despite increasing recognition that CKD may have underlyi ng genetic causes, genetic testing remains limited. This study evaluated the diagnostic yield and phenotypic spectrum of CKD in individuals tested through the KIDNEYCODE sponsored genetic testing program.

Methods

Unrelated individuals who received panel testing (17 genes) through the KIDNEYCODE sponsored genetic testing program were included. Individuals had to meet at least one of the following eligibility criteria: eGFR ≤90 ml/min per 1.73m² and hematuria or a family history of kidney disease; or suspected/biopsy-confirmed Alport syndrome or FSGS in tested individuals or relatives.

Results

Among 859 individuals, 234 (27%) had molecular diagnoses in genes associated with Alport syndrome (n=209), FSGS (n=12), polycystic kidney disease (n=6), and other disorders (n=8). Among those with positive findings in a COL4A gene, the majority were in COL4A5 (n=157, 72 hemizygous male and 85 heterozygous female individuals). A positive family history of CKD, regardless of whether clinical features were reported, was more predictive of a positive finding than was the presence of clinical features alone. For the 248 individuals who had kidney biopsies, a molecular diagnosis was returned for 49 individuals (20%). Most (n=41) individuals had a molecular diagnosis in a COL4A gene, 25 of whom had a previous Alport syndrome clinical diagnosis, and the remaining 16 had previous clinical diagnoses including FSGS (n=2), thin basement membrane disease (n=9), and hematuria (n=1). In total, 491 individuals had a previous clinical diagnosis, 148 (30%) of whom received a molecular diagnosis, the majority (89%, n=131) of which were concordant.

Conclusions

Although skewed to identify individuals with Alport syndrome, these findings support the need to improve access to genetic testing for patients with CKD-particularly in the context of family history of kidney disease, hematuria, and hearing loss.

Eculizumab is a safe and effective treatment in pediatric patients with atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is caused by alternative complement pathway dysregulation, leading to systemic thrombotic microangiopathy (TMA) and severe end-organ damage. Based on 2 prospective studies in mostly adults and retrospective data in children, eculizumab, a terminal complement inhibitor, is approved for aHUS treatment. Here we prospectively evaluated efficacy and safety of weight-based dosing of eculizumab in eligible pediatric patients with aHUS in an open-label phase II study. The primary end point was complete TMA response by 26 weeks. Twenty-two patients (aged 5 months-17 years) were treated; 16 were newly diagnosed, 12 had no prior plasma exchange/infusion during current TMA symptomatology, 11 received baseline dialysis and 2 had prior renal transplants. By week 26, 14 achieved a complete TMA response, 18 achieved hematologic normalization, and 16 had 25% or better improvement in serum creatinine. Plasma exchange/infusion was discontinued in all, and 9 of the 11 patients who required dialysis at baseline discontinued, whereas none initiated new dialysis. Eculizumab was well tolerated; no deaths or meningococcal infections occurred. Bone marrow failure, wrist fracture, and acute respiratory failure were reported as unrelated severe adverse events. Thus, our findings establish the efficacy and safety of eculizumab for pediatric patients with aHUS and are consistent with proposed immediate eculizumab initiation following diagnosis in children.

Comparative value of urinalysis, urine cytology and urine sIL2R in the assessment of renal disease in patients with systemic lupus erythematosus (SLE)

Serial immunological testing has been recently proposed for monitoring patients with lupus nephritis as routine serological tests have shown sub-optimal correlation with clinical status. To assess the value of urine cytology and urine sIL2R in the evaluation of patients with SLE, in particular those with lupus nephritis, we conducted a prospective double-blind study of 31 patients with SLE, during an 18-month period. A comparison of routine urinalysis with urine cytology and urine sIL2R was performed in 84 samples: 15 from patients without a history of renal involvement and 69 from patients with a history of renal involvement. A high urine cytology score (> or = 6), particularly in the presence of lymphoblasts, plasma cells or monocytes, was significantly associated with lupus nephritis in relapse. Urine sIL2R levels were significantly elevated during all SLE relapses, unrelated to the presence of renal involvement. Fifteen urine specimens were obtained at the time of a kidney biopsy: 9 with active lesions and 6 with inactive renal disease. UC score was 2.0 +/- 1.89 for those with absent activity, 8.4 +/- 3.4 for mild activity and 11.0 +/- 2.4 for moderate/severe activity (p < 0.001 between active vs inactive disease). No urinalysis parameter alone permitted distinguishing the degree of renal disease activity. In the subgroup of patients with renal disease urinalysis was overall less accurate than urine cytology or urinary sIL2R levels for predicting renal disease activity defined by biopsy. Urine cytology and urine sIL2R proved to be reliable measures of lupus activity.

A randomized double-blind placebo-controlled trial of cyclosporine in steroid-resistant idiopathic focal segmental glomerulosclerosis in children

There is no generally accepted treatment for primary focal segmental glomerulosclerosis (FSGS). Steroids alone and steroids plus cyclophosphamide can be expected to induce a remission of the proteinuria in only 27% of patients. Probably the majority of FSGS patients will reach ESRD over the extended course of their disease. In addition to the work presented in this study, there have been many reports of the potential effectiveness of cyclosporine (CSA) on reducing the proteinuria of FSGS. This study was undertaken to test the efficacy and safety of a 6-month course of CSA in a double-blinded, prospectively randomized, placebo-controlled trial in children with corticosteroid-resistant FSGS. The potential inhibitory effect of hypercholesterolemia on the proteinuria-reducing actions of CSA was also assessed. Twenty-five patients with FSGS were randomized to receive either placebo or CSA for 6 months. Twelve of the 12 patients that received CSA experienced a diminution of their proteinuria as opposed to only two of the 12 placebo-treated patients. Proteinuria was significantly reduced from 151.7 +/- 162.4 mg/kg per 24 h at Week 0 to 36.9 +/- 42.3 at the end of the study in the group that received CSA (P < 0.05). There was no significant change in the proteinuria of the patients in the placebo group. A significant correlation between the percentage change of proteinuria over the 6 months of the study and the prestudy serum cholesterol levels (r = 0.79, P < 0.05) was seen in the CSA group. A partial correlation analysis controlling for the effects of serum cholesterol uncovered a significant relationship between average CSA level and proteinuria change (r = -0.76, P < 0.05). The fractional decline in GFR over the course of the study was not significantly different between the CSA and placebo-treated groups. In conclusion, CSA reduces proteinuria, increases serum albumin levels, and can be expected, therefore, to reduce the symptoms of nephrotic syndrome. Hypercholesterolemia antagonizes this effect of CSA.

Urine cytology and urine flow cytometry in renal transplantation--a prospective double blind study

Urine cytology (UC) has proved to correlate well with core and fine-needle aspiration kidney biopsies of renal allograft recipients undergoing acute rejection (AR). This study was undertaken to compare the relative usefulness of urine flow immunocytometry (UFC) (using fluorescinated antibodies anti-HLA-DR, anti-CD3 and antirenal epithelial cells) with UC in its ability to diagnose AR by analyzing 200 urine specimens during a prospective double-blind study of 40 renal transplant recipients. Clinical diagnosis was retrospectively assigned to one of the following categories: group I--AR, 15; group II--ischemic injury period (first 5 days postop.), 12; group III, 173 (including 168 stable grafts, 1 pyelonephritis and 4 cyclosporine toxicity), by investigators blinded to the urine results. Both tests were highly sensitive for the diagnosis of AR (UC = 86.6% vs. UFC = 100%; P = NS) with a specificity after the ischemic injury period of 78% by UC and 87.9% by UFC. Samples obtained during AR revealed higher levels of expression of HLA-DR as well as higher numbers of CD3-positive cells. These tests had specificity values of 95.3% and 97.6%, respectively, for the diagnosis of AR. The degree of immune activation (established by numbers of lymphocytes/lymphoblasts seen by UC) correlated with the severity of biopsy-proven ARs and with response to antirejection therapy. In conclusion, both test are highly accurate in diagnosing AR. The highest specificity value was obtained when both UC and UFC were utilized together (93%). We suggest that the routine use of these tests can provide an important adjunct to the evaluation of renal transplant recipients.

Risk of steroid withdrawal in pediatric renal allograft recipients (a 5-year follow-up)

Withdrawal of steroid therapy in renal allograft recipients remains controversial despite the many side effects of this treatment. We have previously presented data on 16 pediatric renal transplant recipients in whom prednisone was withdrawn 6 months or later post-transplantation. To assess the impact of steroid withdrawal, we retrospectively compared this group of patients (Group 1) with a group of 12 patients (Group 2) with renal transplants who continued on prednisone. The groups were compared as to age, sex, ethnicity, source of graft, number of HLA-DR mismatches and incidence of ATN in the immediate postoperative period. The only significant difference was that Group 2 was older. Group 1 had significantly fewer episodes of early acute rejection in the first 6 months post-transplantation than the control group (3/16 vs 8/12, p = 0.009) but nevertheless, without prednisone, had significantly more late acute rejections (11/16 vs 3/12, p = 0.03). Acute rejections occurred as late as 4 years after withdrawal of steroids. Only 5 of the 16 patients in Group 1 have maintained stable graft function without steroids. All of these patients are now alive more than 5 years after steroid withdrawal. In comparing these patients to the other 11, who failed a trial of steroid withdrawal, we found that a serum creatinine of less than 1.7 mg/dl at the time of withdrawal of steroids was predictive of a successful outcome (p = 0.03). In conclusion, withdrawing steroids in pediatric renal allograft recipients has a high risk of late acute rejection and subsequent graft loss, especially for those who have higher baseline creatinine levels.

Evidence that the systematic analysis of bile cytology permits monitoring of hepatic allograft rejection

Cytologic analysis was performed on 128 bile specimens collected by schedule from 12 liver transplant recipients over a 4-month period. Clinical diagnoses at the time of specimen collection were determined retrospectively, as follows: clinically stable, 75; acute rejection, 15; CMV hepatitis, 1; systemic infection, 8; ischemic injury, 24 (all within the first 4 days postop); nonclassifiable, 5. Bile analysis was done by a blinded investigator. Specimens contained ductal epithelial cells (EC) and inflammatory cells (IC), which were counted using Cytospin slide preparations. Greater than 10 cells/slide were seen in 93.3% of rejections, 91.7% of ischemic injuries, 100% of systemic infections, and 14.6% of stable patients. In samples collected after POD 4, IC were seen in 86.7% of rejections, yielding a specificity of 94.4% (P less than 0.001). If lymphoblastic cells were also seen, the specificity increased to 96.6%. Five specimens were obtained the day before the clinical diagnosis of rejection; all demonstrated IC. Seven specimens were obtained 3 days after beginning therapy for rejection. In 5 the bile contained no IC, and clinical improvement occurred; in the 2 in whom IC were found, further therapy was subsequently required. IC were seen in 5 of 8 specimens taken when systemic infection was present; the clinical setting allowed differentiation from rejection. Only 1 case of CMV hepatitis was included, thus no conclusions can be drawn for this entity. Cytoplasmic vacuolization of EC was observed in 30% of cases, in these, cyclosporine levels were significantly higher (989.9 +/- 356.9 vs. 672.8 +/- 421.2, P = 0.02). In summary, bile cytology analysis aides in the monitoring of the onset and duration of rejection. It may be an indicator of persistent rejection, and it may help prevent overimmunosuppression in those cases with normal cytological findings.

Follow-up of cyclosporine-treated pediatric renal allograft recipients after cessation of prednisone

We attempted cessation of prednisone therapy in 16 pediatric renal allograft recipients who were between the ages of 3 1/2 and 16 years at the time of transplantation. Fourteen had primary grafts and 2 had second grafts. Nine had cadaver and 7 had living-related donor grafts. At the time of cessation of prednisone, cyclosporine was the only other immunosuppressive therapy for 15 of the patients and 1 patient was receiving CsA and azathioprine. All the patients had stable serum creatinines at the time prednisone was stopped, between 7 months and 5 years posttransplantation. Seven patients have had no episodes of rejection, continuing to receive CsA as their only immunosuppressive therapy and have stable renal function between 16 months and 3 1/2 years (mean: 2 years) after stopping prednisone. Stopping the small maintenance dose of prednisone resulted in improved growth in patients whose epiphyses were not fused. They improved their weight:height ratios and lost their cushingoid appearance. Serum cholesterol levels declined significantly. Patients who required antihypertensive drugs to control their blood pressure while receiving prednisone required fewer or no drugs when off prednisone. Nine patients had acute rejection episodes and were put back on maintenance prednisone following a 3-day steroid pulse. All these patients had a prompt improvement in renal function following the steroid pulse. However, only 3 stabilized function at preprotocol baseline Scr. Four currently have functioning grafts with Scr greater than the preprotocol Scr. Two patients have returned to dialysis. Although stopping steroids is a worthy goal in pediatric renal allograft recipients, we cannot recommend this strategy as routine management because of the 56% rate of acute rejection episodes in the patients who had prednisone withdrawn.

Characteristics of social networks in adolescents with end-stage renal disease treated with renal transplantation

In adolescents, the establishment of same- and opposite-sex nonfamily peer relations facilitates the normal development of independence and separation from family. Adolescents with end-stage renal disease (ESRD) may be particularly vulnerable to delayed social development and isolation from their peers because of the unique physical and psychosocial aspects of their illness. The characteristics of the social networks of 16 adolescents with ESRD treated with renal transplantation were studied using the Social Networks of Youth Questionnaire. Compared with a matched group of healthy adolescents, these teenagers named fewer significant others in their total social networks, as well as fewer unrelated and opposite-sex peers. Family members comprised a greater proportion of the transplant patients' networks compared to controls. Self-esteem, measured by the Coopersmith Self-Esteem Scale, was similar for transplant and control groups, with the exception of home self-esteem, which was higher in the chronically ill adolescents. Body image was somewhat lower, but not significantly, in adolescents with ESRD. The characteristics of the chronically ill adolescents' social networks suggest that these patients may experience a degree of social isolation. Interventions that promote increased peer contacts and enhance interpersonal skills should be included in the psychosocial management of adolescents with ESRD after renal transplantation.

Immunopharmacodynamic profiles in children with renal allografts receiving cyclosporine therapy

Eleven renal transplant patients between the ages of 4 and 19 years, on a single daily oral dose of cyclosporine (CsA) and either a low oral dose or no dose of prednisone, had venous blood drawn at periodic intervals throughout a 24-hour period. CsA levels were measured by whole blood radioimmunoassay. All the patients had similar patterns of CsA pharmacokinetics with a single peak blood level at two to eight hours after the drug was given. Plasmas separated from the bloods at 37 degrees C were added to third party mixed lymphocyte reactions (MLR). The kinetics of suppression of the MLR by serial plasmas did not follow the CsA levels. Instead, we observed patterns of suppression similar to those that have been described in adults. Five patients had pattern I with two peaks of plasma-mediated MLR suppression, and had no rejection episodes. Two of the patients had pattern II with only one peak of MLR suppression, and both had episodes of acute rejection. One patient showed pattern III with a pleateau of MLR suppression, and has had no rejection episodes and no obvious CsA toxicity. Three patients showed pattern IV with a continuously low level of plasma-mediated MLR suppression throughout the day, and two of them have had severe rejection episodes. Immunopharmacodynamic profiling (IP) may prove to be useful in individualizing therapeutic regimens for patients with renal allografts treated with CsA.

Continuous arteriovenous hemofiltration in children

Continuous arteriovenous hemofiltration (CAVH) is an extracorporeal technique for the treatment of hypervolemia and electrolyte disturbances in the critically ill patient with oligoanuria. The patient's cardiac output provides the blood flow through the circuit; no pumps are necessary. A range of hemofilters is now available extending the applicability of CAVH to the pediatric population, including premature newborns. In this report the treatment of 15 neonates and 8 older children is described. Fluid overload was reduced in all cases. Reflecting the very grave clinical conditions of these patients, 15 of the 23 treated children ultimately died. Due to failure to control uremia, four patients required treatment with dialysis. CAVH was found to be generally safe and effective even in the hemodynamically unstable critically ill child.

Senior-Loken syndrome (familial renal-retinal dystrophy) and Coats' disease

Senior-Loken syndrome is a rare hereditary disease that combines a disorder resembling familial juvenile nephronophthisis with retinitis pigmentosa. Retinitis pigmentosa is even less frequently associated with exudative retinopathy. The patient, a 15-year-old boy, had hereditary renal-retinal dystrophy combined with an exudative vasculopathy of the Coats' type. The patient is on thrice-weekly hemodialysis after two kidney transplants failed. One eye became painful and blind and was eventually enucleated.